/src/postgres/src/backend/parser/parse_coerce.c

Source
/*-------------------------------------------------------------------------
 *
 * parse_coerce.c
 *    handle type coercions/conversions for parser
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/parser/parse_coerce.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/htup_details.h"
#include "catalog/pg_cast.h"
#include "catalog/pg_class.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "parser/parse_coerce.h"
#include "parser/parse_relation.h"
#include "parser/parse_type.h"
#include "utils/builtins.h"
#include "utils/datum.h"    /* needed for datumIsEqual() */
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"
#include "utils/typcache.h"


static Node *coerce_type_typmod(Node *node,
                Oid targetTypeId, int32 targetTypMod,
                CoercionContext ccontext, CoercionForm cformat,
                int location,
                bool hideInputCoercion);
static void hide_coercion_node(Node *node);
static Node *build_coercion_expression(Node *node,
                     CoercionPathType pathtype,
                     Oid funcId,
                     Oid targetTypeId, int32 targetTypMod,
                     CoercionContext ccontext, CoercionForm cformat,
                     int location);
static Node *coerce_record_to_complex(ParseState *pstate, Node *node,
                    Oid targetTypeId,
                    CoercionContext ccontext,
                    CoercionForm cformat,
                    int location);
static bool is_complex_array(Oid typid);
static bool typeIsOfTypedTable(Oid reltypeId, Oid reloftypeId);


/*
 * coerce_to_target_type()
 *    Convert an expression to a target type and typmod.
 *
 * This is the general-purpose entry point for arbitrary type coercion
 * operations.  Direct use of the component operations can_coerce_type,
 * coerce_type, and coerce_type_typmod should be restricted to special
 * cases (eg, when the conversion is expected to succeed).
 *
 * Returns the possibly-transformed expression tree, or NULL if the type
 * conversion is not possible.  (We do this, rather than ereport'ing directly,
 * so that callers can generate custom error messages indicating context.)
 *
 * pstate - parse state (can be NULL, see coerce_type)
 * expr - input expression tree (already transformed by transformExpr)
 * exprtype - result type of expr
 * targettype - desired result type
 * targettypmod - desired result typmod
 * ccontext, cformat - context indicators to control coercions
 * location - parse location of the coercion request, or -1 if unknown/implicit
 */
Node *
coerce_to_target_type(ParseState *pstate, Node *expr, Oid exprtype,
            Oid targettype, int32 targettypmod,
            CoercionContext ccontext,
            CoercionForm cformat,
            int location)
{
  Node     *result;
  Node     *origexpr;

  if (!can_coerce_type(1, &exprtype, &targettype, ccontext))
    return NULL;

  /*
   * If the input has a CollateExpr at the top, strip it off, perform the
   * coercion, and put a new one back on.  This is annoying since it
   * duplicates logic in coerce_type, but if we don't do this then it's too
   * hard to tell whether coerce_type actually changed anything, and we
   * *must* know that to avoid possibly calling hide_coercion_node on
   * something that wasn't generated by coerce_type.  Note that if there are
   * multiple stacked CollateExprs, we just discard all but the topmost.
   * Also, if the target type isn't collatable, we discard the CollateExpr.
   */
  origexpr = expr;
  while (expr && IsA(expr, CollateExpr))
    expr = (Node *) ((CollateExpr *) expr)->arg;

  result = coerce_type(pstate, expr, exprtype,
             targettype, targettypmod,
             ccontext, cformat, location);

  /*
   * If the target is a fixed-length type, it may need a length coercion as
   * well as a type coercion.  If we find ourselves adding both, force the
   * inner coercion node to implicit display form.
   */
  result = coerce_type_typmod(result,
                targettype, targettypmod,
                ccontext, cformat, location,
                (result != expr && !IsA(result, Const)));

  if (expr != origexpr && type_is_collatable(targettype))
  {
    /* Reinstall top CollateExpr */
    CollateExpr *coll = (CollateExpr *) origexpr;
    CollateExpr *newcoll = makeNode(CollateExpr);

    newcoll->arg = (Expr *) result;
    newcoll->collOid = coll->collOid;
    newcoll->location = coll->location;
    result = (Node *) newcoll;
  }

  return result;
}


/*
 * coerce_type()
 *    Convert an expression to a different type.
 *
 * The caller should already have determined that the coercion is possible;
 * see can_coerce_type.
 *
 * Normally, no coercion to a typmod (length) is performed here.  The caller
 * must call coerce_type_typmod as well, if a typmod constraint is wanted.
 * (But if the target type is a domain, it may internally contain a
 * typmod constraint, which will be applied inside coerce_to_domain.)
 * In some cases pg_cast specifies a type coercion function that also
 * applies length conversion, and in those cases only, the result will
 * already be properly coerced to the specified typmod.
 *
 * pstate is only used in the case that we are able to resolve the type of
 * a previously UNKNOWN Param.  It is okay to pass pstate = NULL if the
 * caller does not want type information updated for Params.
 *
 * Note: this function must not modify the given expression tree, only add
 * decoration on top of it.  See transformSetOperationTree, for example.
 */
Node *
coerce_type(ParseState *pstate, Node *node,
      Oid inputTypeId, Oid targetTypeId, int32 targetTypeMod,
      CoercionContext ccontext, CoercionForm cformat, int location)
{
  Node     *result;
  CoercionPathType pathtype;
  Oid     funcId;

  if (targetTypeId == inputTypeId ||
    node == NULL)
  {
    /* no conversion needed */
    return node;
  }
  if (targetTypeId == ANYOID ||
    targetTypeId == ANYELEMENTOID ||
    targetTypeId == ANYNONARRAYOID ||
    targetTypeId == ANYCOMPATIBLEOID ||
    targetTypeId == ANYCOMPATIBLENONARRAYOID)
  {
    /*
     * Assume can_coerce_type verified that implicit coercion is okay.
     *
     * Note: by returning the unmodified node here, we are saying that
     * it's OK to treat an UNKNOWN constant as a valid input for a
     * function accepting one of these pseudotypes.  This should be all
     * right, since an UNKNOWN value is still a perfectly valid Datum.
     *
     * NB: we do NOT want a RelabelType here: the exposed type of the
     * function argument must be its actual type, not the polymorphic
     * pseudotype.
     */
    return node;
  }
  if (targetTypeId == ANYARRAYOID ||
    targetTypeId == ANYENUMOID ||
    targetTypeId == ANYRANGEOID ||
    targetTypeId == ANYMULTIRANGEOID ||
    targetTypeId == ANYCOMPATIBLEARRAYOID ||
    targetTypeId == ANYCOMPATIBLERANGEOID ||
    targetTypeId == ANYCOMPATIBLEMULTIRANGEOID)
  {
    /*
     * Assume can_coerce_type verified that implicit coercion is okay.
     *
     * These cases are unlike the ones above because the exposed type of
     * the argument must be an actual array, enum, range, or multirange
     * type.  In particular the argument must *not* be an UNKNOWN
     * constant.  If it is, we just fall through; below, we'll call the
     * pseudotype's input function, which will produce an error.  Also, if
     * what we have is a domain over array, enum, range, or multirange, we
     * have to relabel it to its base type.
     *
     * Note: currently, we can't actually see a domain-over-enum here,
     * since the other functions in this file will not match such a
     * parameter to ANYENUM.  But that should get changed eventually.
     */
    if (inputTypeId != UNKNOWNOID)
    {
      Oid     baseTypeId = getBaseType(inputTypeId);

      if (baseTypeId != inputTypeId)
      {
        RelabelType *r = makeRelabelType((Expr *) node,
                         baseTypeId, -1,
                         InvalidOid,
                         cformat);

        r->location = location;
        return (Node *) r;
      }
      /* Not a domain type, so return it as-is */
      return node;
    }
  }
  if (inputTypeId == UNKNOWNOID && IsA(node, Const))
  {
    /*
     * Input is a string constant with previously undetermined type. Apply
     * the target type's typinput function to it to produce a constant of
     * the target type.
     *
     * NOTE: this case cannot be folded together with the other
     * constant-input case, since the typinput function does not
     * necessarily behave the same as a type conversion function. For
     * example, int4's typinput function will reject "1.2", whereas
     * float-to-int type conversion will round to integer.
     *
     * XXX if the typinput function is not immutable, we really ought to
     * postpone evaluation of the function call until runtime. But there
     * is no way to represent a typinput function call as an expression
     * tree, because C-string values are not Datums. (XXX This *is*
     * possible as of 7.3, do we want to do it?)
     */
    Const    *con = (Const *) node;
    Const    *newcon = makeNode(Const);
    Oid     baseTypeId;
    int32   baseTypeMod;
    int32   inputTypeMod;
    Type    baseType;
    ParseCallbackState pcbstate;

    /*
     * If the target type is a domain, we want to call its base type's
     * input routine, not domain_in().  This is to avoid premature failure
     * when the domain applies a typmod: existing input routines follow
     * implicit-coercion semantics for length checks, which is not always
     * what we want here.  The needed check will be applied properly
     * inside coerce_to_domain().
     */
    baseTypeMod = targetTypeMod;
    baseTypeId = getBaseTypeAndTypmod(targetTypeId, &baseTypeMod);

    /*
     * For most types we pass typmod -1 to the input routine, because
     * existing input routines follow implicit-coercion semantics for
     * length checks, which is not always what we want here.  Any length
     * constraint will be applied later by our caller.  An exception
     * however is the INTERVAL type, for which we *must* pass the typmod
     * or it won't be able to obey the bizarre SQL-spec input rules. (Ugly
     * as sin, but so is this part of the spec...)
     */
    if (baseTypeId == INTERVALOID)
      inputTypeMod = baseTypeMod;
    else
      inputTypeMod = -1;

    baseType = typeidType(baseTypeId);

    newcon->consttype = baseTypeId;
    newcon->consttypmod = inputTypeMod;
    newcon->constcollid = typeTypeCollation(baseType);
    newcon->constlen = typeLen(baseType);
    newcon->constbyval = typeByVal(baseType);
    newcon->constisnull = con->constisnull;

    /*
     * We use the original literal's location regardless of the position
     * of the coercion.  This is a change from pre-9.2 behavior, meant to
     * simplify life for pg_stat_statements.
     */
    newcon->location = con->location;

    /*
     * Set up to point at the constant's text if the input routine throws
     * an error.
     */
    setup_parser_errposition_callback(&pcbstate, pstate, con->location);

    /*
     * We assume here that UNKNOWN's internal representation is the same
     * as CSTRING.
     */
    if (!con->constisnull)
      newcon->constvalue = stringTypeDatum(baseType,
                         DatumGetCString(con->constvalue),
                         inputTypeMod);
    else
      newcon->constvalue = stringTypeDatum(baseType,
                         NULL,
                         inputTypeMod);

    /*
     * If it's a varlena value, force it to be in non-expanded
     * (non-toasted) format; this avoids any possible dependency on
     * external values and improves consistency of representation.
     */
    if (!con->constisnull && newcon->constlen == -1)
      newcon->constvalue =
        PointerGetDatum(PG_DETOAST_DATUM(newcon->constvalue));

#ifdef RANDOMIZE_ALLOCATED_MEMORY

    /*
     * For pass-by-reference data types, repeat the conversion to see if
     * the input function leaves any uninitialized bytes in the result. We
     * can only detect that reliably if RANDOMIZE_ALLOCATED_MEMORY is
     * enabled, so we don't bother testing otherwise.  The reason we don't
     * want any instability in the input function is that comparison of
     * Const nodes relies on bytewise comparison of the datums, so if the
     * input function leaves garbage then subexpressions that should be
     * identical may not get recognized as such.  See pgsql-hackers
     * discussion of 2008-04-04.
     */
    if (!con->constisnull && !newcon->constbyval)
    {
      Datum   val2;

      val2 = stringTypeDatum(baseType,
                   DatumGetCString(con->constvalue),
                   inputTypeMod);
      if (newcon->constlen == -1)
        val2 = PointerGetDatum(PG_DETOAST_DATUM(val2));
      if (!datumIsEqual(newcon->constvalue, val2, false, newcon->constlen))
        elog(WARNING, "type %s has unstable input conversion for \"%s\"",
           typeTypeName(baseType), DatumGetCString(con->constvalue));
    }
#endif

    cancel_parser_errposition_callback(&pcbstate);

    result = (Node *) newcon;

    /* If target is a domain, apply constraints. */
    if (baseTypeId != targetTypeId)
      result = coerce_to_domain(result,
                    baseTypeId, baseTypeMod,
                    targetTypeId,
                    ccontext, cformat, location,
                    false);

    ReleaseSysCache(baseType);

    return result;
  }
  if (IsA(node, Param) &&
    pstate != NULL && pstate->p_coerce_param_hook != NULL)
  {
    /*
     * Allow the CoerceParamHook to decide what happens.  It can return a
     * transformed node (very possibly the same Param node), or return
     * NULL to indicate we should proceed with normal coercion.
     */
    result = pstate->p_coerce_param_hook(pstate,
                       (Param *) node,
                       targetTypeId,
                       targetTypeMod,
                       location);
    if (result)
      return result;
  }
  if (IsA(node, CollateExpr))
  {
    /*
     * If we have a COLLATE clause, we have to push the coercion
     * underneath the COLLATE; or discard the COLLATE if the target type
     * isn't collatable.  This is really ugly, but there is little choice
     * because the above hacks on Consts and Params wouldn't happen
     * otherwise.  This kluge has consequences in coerce_to_target_type.
     */
    CollateExpr *coll = (CollateExpr *) node;

    result = coerce_type(pstate, (Node *) coll->arg,
               inputTypeId, targetTypeId, targetTypeMod,
               ccontext, cformat, location);
    if (type_is_collatable(targetTypeId))
    {
      CollateExpr *newcoll = makeNode(CollateExpr);

      newcoll->arg = (Expr *) result;
      newcoll->collOid = coll->collOid;
      newcoll->location = coll->location;
      result = (Node *) newcoll;
    }
    return result;
  }
  pathtype = find_coercion_pathway(targetTypeId, inputTypeId, ccontext,
                   &funcId);
  if (pathtype != COERCION_PATH_NONE)
  {
    Oid     baseTypeId;
    int32   baseTypeMod;

    baseTypeMod = targetTypeMod;
    baseTypeId = getBaseTypeAndTypmod(targetTypeId, &baseTypeMod);

    if (pathtype != COERCION_PATH_RELABELTYPE)
    {
      /*
       * Generate an expression tree representing run-time application
       * of the conversion function.  If we are dealing with a domain
       * target type, the conversion function will yield the base type,
       * and we need to extract the correct typmod to use from the
       * domain's typtypmod.
       */
      result = build_coercion_expression(node, pathtype, funcId,
                         baseTypeId, baseTypeMod,
                         ccontext, cformat, location);

      /*
       * If domain, coerce to the domain type and relabel with domain
       * type ID, hiding the previous coercion node.
       */
      if (targetTypeId != baseTypeId)
        result = coerce_to_domain(result, baseTypeId, baseTypeMod,
                      targetTypeId,
                      ccontext, cformat, location,
                      true);
    }
    else
    {
      /*
       * We don't need to do a physical conversion, but we do need to
       * attach a RelabelType node so that the expression will be seen
       * to have the intended type when inspected by higher-level code.
       *
       * Also, domains may have value restrictions beyond the base type
       * that must be accounted for.  If the destination is a domain
       * then we won't need a RelabelType node.
       */
      result = coerce_to_domain(node, baseTypeId, baseTypeMod,
                    targetTypeId,
                    ccontext, cformat, location,
                    false);
      if (result == node)
      {
        /*
         * XXX could we label result with exprTypmod(node) instead of
         * default -1 typmod, to save a possible length-coercion
         * later? Would work if both types have same interpretation of
         * typmod, which is likely but not certain.
         */
        RelabelType *r = makeRelabelType((Expr *) result,
                         targetTypeId, -1,
                         InvalidOid,
                         cformat);

        r->location = location;
        result = (Node *) r;
      }
    }
    return result;
  }
  if (inputTypeId == RECORDOID &&
    ISCOMPLEX(targetTypeId))
  {
    /* Coerce a RECORD to a specific complex type */
    return coerce_record_to_complex(pstate, node, targetTypeId,
                    ccontext, cformat, location);
  }
  if (targetTypeId == RECORDOID &&
    ISCOMPLEX(inputTypeId))
  {
    /* Coerce a specific complex type to RECORD */
    /* NB: we do NOT want a RelabelType here */
    return node;
  }
#ifdef NOT_USED
  if (inputTypeId == RECORDARRAYOID &&
    is_complex_array(targetTypeId))
  {
    /* Coerce record[] to a specific complex array type */
    /* not implemented yet ... */
  }
#endif
  if (targetTypeId == RECORDARRAYOID &&
    is_complex_array(inputTypeId))
  {
    /* Coerce a specific complex array type to record[] */
    /* NB: we do NOT want a RelabelType here */
    return node;
  }
  if (typeInheritsFrom(inputTypeId, targetTypeId)
    || typeIsOfTypedTable(inputTypeId, targetTypeId))
  {
    /*
     * Input class type is a subclass of target, so generate an
     * appropriate runtime conversion (removing unneeded columns and
     * possibly rearranging the ones that are wanted).
     *
     * We will also get here when the input is a domain over a subclass of
     * the target type.  To keep life simple for the executor, we define
     * ConvertRowtypeExpr as only working between regular composite types;
     * therefore, in such cases insert a RelabelType to smash the input
     * expression down to its base type.
     */
    Oid     baseTypeId = getBaseType(inputTypeId);
    ConvertRowtypeExpr *r = makeNode(ConvertRowtypeExpr);

    if (baseTypeId != inputTypeId)
    {
      RelabelType *rt = makeRelabelType((Expr *) node,
                        baseTypeId, -1,
                        InvalidOid,
                        COERCE_IMPLICIT_CAST);

      rt->location = location;
      node = (Node *) rt;
    }
    r->arg = (Expr *) node;
    r->resulttype = targetTypeId;
    r->convertformat = cformat;
    r->location = location;
    return (Node *) r;
  }
  /* If we get here, caller blew it */
  elog(ERROR, "failed to find conversion function from %s to %s",
     format_type_be(inputTypeId), format_type_be(targetTypeId));
  return NULL;       /* keep compiler quiet */
}


/*
 * can_coerce_type()
 *    Can input_typeids be coerced to target_typeids?
 *
 * We must be told the context (CAST construct, assignment, implicit coercion)
 * as this determines the set of available casts.
 */
bool
can_coerce_type(int nargs, const Oid *input_typeids, const Oid *target_typeids,
        CoercionContext ccontext)
{
  bool    have_generics = false;
  int     i;

  /* run through argument list... */
  for (i = 0; i < nargs; i++)
  {
    Oid     inputTypeId = input_typeids[i];
    Oid     targetTypeId = target_typeids[i];
    CoercionPathType pathtype;
    Oid     funcId;

    /* no problem if same type */
    if (inputTypeId == targetTypeId)
      continue;

    /* reject all cases of casting something else to/from "internal" */
    if (inputTypeId == INTERNALOID || targetTypeId == INTERNALOID)
      return false;

    /* accept if target is ANY */
    if (targetTypeId == ANYOID)
      continue;

    /* accept if target is polymorphic, for now */
    if (IsPolymorphicType(targetTypeId))
    {
      have_generics = true; /* do more checking later */
      continue;
    }

    /*
     * If input is an untyped string constant, assume we can convert it to
     * anything.
     */
    if (inputTypeId == UNKNOWNOID)
      continue;

    /*
     * If pg_cast shows that we can coerce, accept.  This test now covers
     * both binary-compatible and coercion-function cases.
     */
    pathtype = find_coercion_pathway(targetTypeId, inputTypeId, ccontext,
                     &funcId);
    if (pathtype != COERCION_PATH_NONE)
      continue;

    /*
     * If input is RECORD and target is a composite type, assume we can
     * coerce (may need tighter checking here)
     */
    if (inputTypeId == RECORDOID &&
      ISCOMPLEX(targetTypeId))
      continue;

    /*
     * If input is a composite type and target is RECORD, accept
     */
    if (targetTypeId == RECORDOID &&
      ISCOMPLEX(inputTypeId))
      continue;

#ifdef NOT_USED         /* not implemented yet */

    /*
     * If input is record[] and target is a composite array type, assume
     * we can coerce (may need tighter checking here)
     */
    if (inputTypeId == RECORDARRAYOID &&
      is_complex_array(targetTypeId))
      continue;
#endif

    /*
     * If input is a composite array type and target is record[], accept
     */
    if (targetTypeId == RECORDARRAYOID &&
      is_complex_array(inputTypeId))
      continue;

    /*
     * If input is a class type that inherits from target, accept
     */
    if (typeInheritsFrom(inputTypeId, targetTypeId)
      || typeIsOfTypedTable(inputTypeId, targetTypeId))
      continue;

    /*
     * Else, cannot coerce at this argument position
     */
    return false;
  }

  /* If we found any generic argument types, cross-check them */
  if (have_generics)
  {
    if (!check_generic_type_consistency(input_typeids, target_typeids,
                      nargs))
      return false;
  }

  return true;
}


/*
 * Create an expression tree to represent coercion to a domain type.
 *
 * 'arg': input expression
 * 'baseTypeId': base type of domain
 * 'baseTypeMod': base type typmod of domain
 * 'typeId': target type to coerce to
 * 'ccontext': context indicator to control coercions
 * 'cformat': coercion display format
 * 'location': coercion request location
 * 'hideInputCoercion': if true, hide the input coercion under this one.
 *
 * If the target type isn't a domain, the given 'arg' is returned as-is.
 */
Node *
coerce_to_domain(Node *arg, Oid baseTypeId, int32 baseTypeMod, Oid typeId,
         CoercionContext ccontext, CoercionForm cformat, int location,
         bool hideInputCoercion)
{
  CoerceToDomain *result;

  /* We now require the caller to supply correct baseTypeId/baseTypeMod */
  Assert(OidIsValid(baseTypeId));

  /* If it isn't a domain, return the node as it was passed in */
  if (baseTypeId == typeId)
    return arg;

  /* Suppress display of nested coercion steps */
  if (hideInputCoercion)
    hide_coercion_node(arg);

  /*
   * If the domain applies a typmod to its base type, build the appropriate
   * coercion step.  Mark it implicit for display purposes, because we don't
   * want it shown separately by ruleutils.c; but the isExplicit flag passed
   * to the conversion function depends on the manner in which the domain
   * coercion is invoked, so that the semantics of implicit and explicit
   * coercion differ.  (Is that really the behavior we want?)
   *
   * NOTE: because we apply this as part of the fixed expression structure,
   * ALTER DOMAIN cannot alter the typtypmod.  But it's unclear that that
   * would be safe to do anyway, without lots of knowledge about what the
   * base type thinks the typmod means.
   */
  arg = coerce_type_typmod(arg, baseTypeId, baseTypeMod,
               ccontext, COERCE_IMPLICIT_CAST, location,
               false);

  /*
   * Now build the domain coercion node.  This represents run-time checking
   * of any constraints currently attached to the domain.  This also ensures
   * that the expression is properly labeled as to result type.
   */
  result = makeNode(CoerceToDomain);
  result->arg = (Expr *) arg;
  result->resulttype = typeId;
  result->resulttypmod = -1;  /* currently, always -1 for domains */
  /* resultcollid will be set by parse_collate.c */
  result->coercionformat = cformat;
  result->location = location;

  return (Node *) result;
}


/*
 * coerce_type_typmod()
 *    Force a value to a particular typmod, if meaningful and possible.
 *
 * This is applied to values that are going to be stored in a relation
 * (where we have an atttypmod for the column) as well as values being
 * explicitly CASTed (where the typmod comes from the target type spec).
 *
 * The caller must have already ensured that the value is of the correct
 * type, typically by applying coerce_type.
 *
 * ccontext may affect semantics, depending on whether the length coercion
 * function pays attention to the isExplicit flag it's passed.
 *
 * cformat determines the display properties of the generated node (if any).
 *
 * If hideInputCoercion is true *and* we generate a node, the input node is
 * forced to IMPLICIT display form, so that only the typmod coercion node will
 * be visible when displaying the expression.
 *
 * NOTE: this does not need to work on domain types, because any typmod
 * coercion for a domain is considered to be part of the type coercion
 * needed to produce the domain value in the first place.  So, no getBaseType.
 */
static Node *
coerce_type_typmod(Node *node, Oid targetTypeId, int32 targetTypMod,
           CoercionContext ccontext, CoercionForm cformat,
           int location,
           bool hideInputCoercion)
{
  CoercionPathType pathtype;
  Oid     funcId;

  /* Skip coercion if already done */
  if (targetTypMod == exprTypmod(node))
    return node;

  /* Suppress display of nested coercion steps */
  if (hideInputCoercion)
    hide_coercion_node(node);

  /*
   * A negative typmod means that no actual coercion is needed, but we still
   * want a RelabelType to ensure that the expression exposes the intended
   * typmod.
   */
  if (targetTypMod < 0)
    pathtype = COERCION_PATH_NONE;
  else
    pathtype = find_typmod_coercion_function(targetTypeId, &funcId);

  if (pathtype != COERCION_PATH_NONE)
  {
    node = build_coercion_expression(node, pathtype, funcId,
                     targetTypeId, targetTypMod,
                     ccontext, cformat, location);
  }
  else
  {
    /*
     * We don't need to perform any actual coercion step, but we should
     * apply a RelabelType to ensure that the expression exposes the
     * intended typmod.
     */
    node = applyRelabelType(node, targetTypeId, targetTypMod,
                exprCollation(node),
                cformat, location, false);
  }

  return node;
}

/*
 * Mark a coercion node as IMPLICIT so it will never be displayed by
 * ruleutils.c.  We use this when we generate a nest of coercion nodes
 * to implement what is logically one conversion; the inner nodes are
 * forced to IMPLICIT_CAST format.  This does not change their semantics,
 * only display behavior.
 *
 * It is caller error to call this on something that doesn't have a
 * CoercionForm field.
 */
static void
hide_coercion_node(Node *node)
{
  if (IsA(node, FuncExpr))
    ((FuncExpr *) node)->funcformat = COERCE_IMPLICIT_CAST;
  else if (IsA(node, RelabelType))
    ((RelabelType *) node)->relabelformat = COERCE_IMPLICIT_CAST;
  else if (IsA(node, CoerceViaIO))
    ((CoerceViaIO *) node)->coerceformat = COERCE_IMPLICIT_CAST;
  else if (IsA(node, ArrayCoerceExpr))
    ((ArrayCoerceExpr *) node)->coerceformat = COERCE_IMPLICIT_CAST;
  else if (IsA(node, ConvertRowtypeExpr))
    ((ConvertRowtypeExpr *) node)->convertformat = COERCE_IMPLICIT_CAST;
  else if (IsA(node, RowExpr))
    ((RowExpr *) node)->row_format = COERCE_IMPLICIT_CAST;
  else if (IsA(node, CoerceToDomain))
    ((CoerceToDomain *) node)->coercionformat = COERCE_IMPLICIT_CAST;
  else
    elog(ERROR, "unsupported node type: %d", (int) nodeTag(node));
}

/*
 * build_coercion_expression()
 *    Construct an expression tree for applying a pg_cast entry.
 *
 * This is used for both type-coercion and length-coercion operations,
 * since there is no difference in terms of the calling convention.
 */
static Node *
build_coercion_expression(Node *node,
              CoercionPathType pathtype,
              Oid funcId,
              Oid targetTypeId, int32 targetTypMod,
              CoercionContext ccontext, CoercionForm cformat,
              int location)
{
  int     nargs = 0;

  if (OidIsValid(funcId))
  {
    HeapTuple tp;
    Form_pg_proc procstruct;

    tp = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcId));
    if (!HeapTupleIsValid(tp))
      elog(ERROR, "cache lookup failed for function %u", funcId);
    procstruct = (Form_pg_proc) GETSTRUCT(tp);

    /*
     * These Asserts essentially check that function is a legal coercion
     * function.  We can't make the seemingly obvious tests on prorettype
     * and proargtypes[0], even in the COERCION_PATH_FUNC case, because of
     * various binary-compatibility cases.
     */
    /* Assert(targetTypeId == procstruct->prorettype); */
    Assert(!procstruct->proretset);
    Assert(procstruct->prokind == PROKIND_FUNCTION);
    nargs = procstruct->pronargs;
    Assert(nargs >= 1 && nargs <= 3);
    /* Assert(procstruct->proargtypes.values[0] == exprType(node)); */
    Assert(nargs < 2 || procstruct->proargtypes.values[1] == INT4OID);
    Assert(nargs < 3 || procstruct->proargtypes.values[2] == BOOLOID);

    ReleaseSysCache(tp);
  }

  if (pathtype == COERCION_PATH_FUNC)
  {
    /* We build an ordinary FuncExpr with special arguments */
    FuncExpr   *fexpr;
    List     *args;
    Const    *cons;

    Assert(OidIsValid(funcId));

    args = list_make1(node);

    if (nargs >= 2)
    {
      /* Pass target typmod as an int4 constant */
      cons = makeConst(INT4OID,
               -1,
               InvalidOid,
               sizeof(int32),
               Int32GetDatum(targetTypMod),
               false,
               true);

      args = lappend(args, cons);
    }

    if (nargs == 3)
    {
      /* Pass it a boolean isExplicit parameter, too */
      cons = makeConst(BOOLOID,
               -1,
               InvalidOid,
               sizeof(bool),
               BoolGetDatum(ccontext == COERCION_EXPLICIT),
               false,
               true);

      args = lappend(args, cons);
    }

    fexpr = makeFuncExpr(funcId, targetTypeId, args,
               InvalidOid, InvalidOid, cformat);
    fexpr->location = location;
    return (Node *) fexpr;
  }
  else if (pathtype == COERCION_PATH_ARRAYCOERCE)
  {
    /* We need to build an ArrayCoerceExpr */
    ArrayCoerceExpr *acoerce = makeNode(ArrayCoerceExpr);
    CaseTestExpr *ctest = makeNode(CaseTestExpr);
    Oid     sourceBaseTypeId;
    int32   sourceBaseTypeMod;
    Oid     targetElementType;
    Node     *elemexpr;

    /*
     * Look through any domain over the source array type.  Note we don't
     * expect that the target type is a domain; it must be a plain array.
     * (To get to a domain target type, we'll do coerce_to_domain later.)
     */
    sourceBaseTypeMod = exprTypmod(node);
    sourceBaseTypeId = getBaseTypeAndTypmod(exprType(node),
                        &sourceBaseTypeMod);

    /*
     * Set up a CaseTestExpr representing one element of the source array.
     * This is an abuse of CaseTestExpr, but it's OK as long as there
     * can't be any CaseExpr or ArrayCoerceExpr within the completed
     * elemexpr.
     */
    ctest->typeId = get_element_type(sourceBaseTypeId);
    Assert(OidIsValid(ctest->typeId));
    ctest->typeMod = sourceBaseTypeMod;
    ctest->collation = InvalidOid; /* Assume coercions don't care */

    /* And coerce it to the target element type */
    targetElementType = get_element_type(targetTypeId);
    Assert(OidIsValid(targetElementType));

    elemexpr = coerce_to_target_type(NULL,
                     (Node *) ctest,
                     ctest->typeId,
                     targetElementType,
                     targetTypMod,
                     ccontext,
                     cformat,
                     location);
    if (elemexpr == NULL) /* shouldn't happen */
      elog(ERROR, "failed to coerce array element type as expected");

    acoerce->arg = (Expr *) node;
    acoerce->elemexpr = (Expr *) elemexpr;
    acoerce->resulttype = targetTypeId;

    /*
     * Label the output as having a particular element typmod only if we
     * ended up with a per-element expression that is labeled that way.
     */
    acoerce->resulttypmod = exprTypmod(elemexpr);
    /* resultcollid will be set by parse_collate.c */
    acoerce->coerceformat = cformat;
    acoerce->location = location;

    return (Node *) acoerce;
  }
  else if (pathtype == COERCION_PATH_COERCEVIAIO)
  {
    /* We need to build a CoerceViaIO node */
    CoerceViaIO *iocoerce = makeNode(CoerceViaIO);

    Assert(!OidIsValid(funcId));

    iocoerce->arg = (Expr *) node;
    iocoerce->resulttype = targetTypeId;
    /* resultcollid will be set by parse_collate.c */
    iocoerce->coerceformat = cformat;
    iocoerce->location = location;

    return (Node *) iocoerce;
  }
  else
  {
    elog(ERROR, "unsupported pathtype %d in build_coercion_expression",
       (int) pathtype);
    return NULL;     /* keep compiler quiet */
  }
}


/*
 * coerce_record_to_complex
 *    Coerce a RECORD to a specific composite type.
 *
 * Currently we only support this for inputs that are RowExprs or whole-row
 * Vars.
 */
static Node *
coerce_record_to_complex(ParseState *pstate, Node *node,
             Oid targetTypeId,
             CoercionContext ccontext,
             CoercionForm cformat,
             int location)
{
  RowExpr    *rowexpr;
  Oid     baseTypeId;
  int32   baseTypeMod = -1;
  TupleDesc tupdesc;
  List     *args = NIL;
  List     *newargs;
  int     i;
  int     ucolno;
  ListCell   *arg;

  if (node && IsA(node, RowExpr))
  {
    /*
     * Since the RowExpr must be of type RECORD, we needn't worry about it
     * containing any dropped columns.
     */
    args = ((RowExpr *) node)->args;
  }
  else if (node && IsA(node, Var) &&
       ((Var *) node)->varattno == InvalidAttrNumber)
  {
    Var      *var = (Var *) node;
    ParseNamespaceItem *nsitem;

    nsitem = GetNSItemByVar(pstate, var);
    args = expandNSItemVars(pstate, nsitem, var->varlevelsup,
                var->location, NULL);
  }
  else
    ereport(ERROR,
        (errcode(ERRCODE_CANNOT_COERCE),
         errmsg("cannot cast type %s to %s",
            format_type_be(RECORDOID),
            format_type_be(targetTypeId)),
         parser_coercion_errposition(pstate, location, node)));

  /*
   * Look up the composite type, accounting for possibility that what we are
   * given is a domain over composite.
   */
  baseTypeId = getBaseTypeAndTypmod(targetTypeId, &baseTypeMod);
  tupdesc = lookup_rowtype_tupdesc(baseTypeId, baseTypeMod);

  /* Process the fields */
  newargs = NIL;
  ucolno = 1;
  arg = list_head(args);
  for (i = 0; i < tupdesc->natts; i++)
  {
    Node     *expr;
    Node     *cexpr;
    Oid     exprtype;
    Form_pg_attribute attr = TupleDescAttr(tupdesc, i);

    /* Fill in NULLs for dropped columns in rowtype */
    if (attr->attisdropped)
    {
      /*
       * can't use atttypid here, but it doesn't really matter what type
       * the Const claims to be.
       */
      newargs = lappend(newargs,
                makeNullConst(INT4OID, -1, InvalidOid));
      continue;
    }

    if (arg == NULL)
      ereport(ERROR,
          (errcode(ERRCODE_CANNOT_COERCE),
           errmsg("cannot cast type %s to %s",
              format_type_be(RECORDOID),
              format_type_be(targetTypeId)),
           errdetail("Input has too few columns."),
           parser_coercion_errposition(pstate, location, node)));
    expr = (Node *) lfirst(arg);
    exprtype = exprType(expr);

    cexpr = coerce_to_target_type(pstate,
                    expr, exprtype,
                    attr->atttypid,
                    attr->atttypmod,
                    ccontext,
                    COERCE_IMPLICIT_CAST,
                    -1);
    if (cexpr == NULL)
      ereport(ERROR,
          (errcode(ERRCODE_CANNOT_COERCE),
           errmsg("cannot cast type %s to %s",
              format_type_be(RECORDOID),
              format_type_be(targetTypeId)),
           errdetail("Cannot cast type %s to %s in column %d.",
                 format_type_be(exprtype),
                 format_type_be(attr->atttypid),
                 ucolno),
           parser_coercion_errposition(pstate, location, expr)));
    newargs = lappend(newargs, cexpr);
    ucolno++;
    arg = lnext(args, arg);
  }
  if (arg != NULL)
    ereport(ERROR,
        (errcode(ERRCODE_CANNOT_COERCE),
         errmsg("cannot cast type %s to %s",
            format_type_be(RECORDOID),
            format_type_be(targetTypeId)),
         errdetail("Input has too many columns."),
         parser_coercion_errposition(pstate, location, node)));

  ReleaseTupleDesc(tupdesc);

  rowexpr = makeNode(RowExpr);
  rowexpr->args = newargs;
  rowexpr->row_typeid = baseTypeId;
  rowexpr->row_format = cformat;
  rowexpr->colnames = NIL; /* not needed for named target type */
  rowexpr->location = location;

  /* If target is a domain, apply constraints */
  if (baseTypeId != targetTypeId)
  {
    rowexpr->row_format = COERCE_IMPLICIT_CAST;
    return coerce_to_domain((Node *) rowexpr,
                baseTypeId, baseTypeMod,
                targetTypeId,
                ccontext, cformat, location,
                false);
  }

  return (Node *) rowexpr;
}

/*
 * coerce_to_boolean()
 *    Coerce an argument of a construct that requires boolean input
 *    (AND, OR, NOT, etc).  Also check that input is not a set.
 *
 * Returns the possibly-transformed node tree.
 *
 * As with coerce_type, pstate may be NULL if no special unknown-Param
 * processing is wanted.
 */
Node *
coerce_to_boolean(ParseState *pstate, Node *node,
          const char *constructName)
{
  Oid     inputTypeId = exprType(node);

  if (inputTypeId != BOOLOID)
  {
    Node     *newnode;

    newnode = coerce_to_target_type(pstate, node, inputTypeId,
                    BOOLOID, -1,
                    COERCION_ASSIGNMENT,
                    COERCE_IMPLICIT_CAST,
                    -1);
    if (newnode == NULL)
      ereport(ERROR,
          (errcode(ERRCODE_DATATYPE_MISMATCH),
      /* translator: first %s is name of a SQL construct, eg WHERE */
           errmsg("argument of %s must be type %s, not type %s",
              constructName, "boolean",
              format_type_be(inputTypeId)),
           parser_errposition(pstate, exprLocation(node))));
    node = newnode;
  }

  if (expression_returns_set(node))
    ereport(ERROR,
        (errcode(ERRCODE_DATATYPE_MISMATCH),
    /* translator: %s is name of a SQL construct, eg WHERE */
         errmsg("argument of %s must not return a set",
            constructName),
         parser_errposition(pstate, exprLocation(node))));

  return node;
}

/*
 * coerce_to_specific_type_typmod()
 *    Coerce an argument of a construct that requires a specific data type,
 *    with a specific typmod.  Also check that input is not a set.
 *
 * Returns the possibly-transformed node tree.
 *
 * As with coerce_type, pstate may be NULL if no special unknown-Param
 * processing is wanted.
 */
Node *
coerce_to_specific_type_typmod(ParseState *pstate, Node *node,
                 Oid targetTypeId, int32 targetTypmod,
                 const char *constructName)
{
  Oid     inputTypeId = exprType(node);

  if (inputTypeId != targetTypeId)
  {
    Node     *newnode;

    newnode = coerce_to_target_type(pstate, node, inputTypeId,
                    targetTypeId, targetTypmod,
                    COERCION_ASSIGNMENT,
                    COERCE_IMPLICIT_CAST,
                    -1);
    if (newnode == NULL)
      ereport(ERROR,
          (errcode(ERRCODE_DATATYPE_MISMATCH),
      /* translator: first %s is name of a SQL construct, eg LIMIT */
           errmsg("argument of %s must be type %s, not type %s",
              constructName,
              format_type_be(targetTypeId),
              format_type_be(inputTypeId)),
           parser_errposition(pstate, exprLocation(node))));
    node = newnode;
  }

  if (expression_returns_set(node))
    ereport(ERROR,
        (errcode(ERRCODE_DATATYPE_MISMATCH),
    /* translator: %s is name of a SQL construct, eg LIMIT */
         errmsg("argument of %s must not return a set",
            constructName),
         parser_errposition(pstate, exprLocation(node))));

  return node;
}

/*
 * coerce_to_specific_type()
 *    Coerce an argument of a construct that requires a specific data type.
 *    Also check that input is not a set.
 *
 * Returns the possibly-transformed node tree.
 *
 * As with coerce_type, pstate may be NULL if no special unknown-Param
 * processing is wanted.
 */
Node *
coerce_to_specific_type(ParseState *pstate, Node *node,
            Oid targetTypeId,
            const char *constructName)
{
  return coerce_to_specific_type_typmod(pstate, node,
                      targetTypeId, -1,
                      constructName);
}

/*
 * coerce_null_to_domain()
 *    Build a NULL constant, then wrap it in CoerceToDomain
 *    if the desired type is a domain type.  This allows any
 *    NOT NULL domain constraint to be enforced at runtime.
 */
Node *
coerce_null_to_domain(Oid typid, int32 typmod, Oid collation,
            int typlen, bool typbyval)
{
  Node     *result;
  Oid     baseTypeId;
  int32   baseTypeMod = typmod;

  /*
   * The constant must appear to have the domain's base type/typmod, else
   * coerce_to_domain() will apply a length coercion which is useless.
   */
  baseTypeId = getBaseTypeAndTypmod(typid, &baseTypeMod);
  result = (Node *) makeConst(baseTypeId,
                baseTypeMod,
                collation,
                typlen,
                (Datum) 0,
                true, /* isnull */
                typbyval);
  if (typid != baseTypeId)
    result = coerce_to_domain(result,
                  baseTypeId, baseTypeMod,
                  typid,
                  COERCION_IMPLICIT,
                  COERCE_IMPLICIT_CAST,
                  -1,
                  false);
  return result;
}

/*
 * parser_coercion_errposition - report coercion error location, if possible
 *
 * We prefer to point at the coercion request (CAST, ::, etc) if possible;
 * but there may be no such location in the case of an implicit coercion.
 * In that case point at the input expression.
 *
 * XXX possibly this is more generally useful than coercion errors;
 * if so, should rename and place with parser_errposition.
 */
int
parser_coercion_errposition(ParseState *pstate,
              int coerce_location,
              Node *input_expr)
{
  if (coerce_location >= 0)
    return parser_errposition(pstate, coerce_location);
  else
    return parser_errposition(pstate, exprLocation(input_expr));
}


/*
 * select_common_type()
 *    Determine the common supertype of a list of input expressions.
 *    This is used for determining the output type of CASE, UNION,
 *    and similar constructs.
 *
 * 'exprs' is a *nonempty* list of expressions.  Note that earlier items
 * in the list will be preferred if there is doubt.
 * 'context' is a phrase to use in the error message if we fail to select
 * a usable type.  Pass NULL to have the routine return InvalidOid
 * rather than throwing an error on failure.
 * 'which_expr': if not NULL, receives a pointer to the particular input
 * expression from which the result type was taken.
 *
 * Caution: "failure" just means that there were inputs of different type
 * categories.  It is not guaranteed that all the inputs are coercible to the
 * selected type; caller must check that (see verify_common_type).
 */
Oid
select_common_type(ParseState *pstate, List *exprs, const char *context,
           Node **which_expr)
{
  Node     *pexpr;
  Oid     ptype;
  TYPCATEGORY pcategory;
  bool    pispreferred;
  ListCell   *lc;

  Assert(exprs != NIL);
  pexpr = (Node *) linitial(exprs);
  lc = list_second_cell(exprs);
  ptype = exprType(pexpr);

  /*
   * If all input types are valid and exactly the same, just pick that type.
   * This is the only way that we will resolve the result as being a domain
   * type; otherwise domains are smashed to their base types for comparison.
   */
  if (ptype != UNKNOWNOID)
  {
    for_each_cell(lc, exprs, lc)
    {
      Node     *nexpr = (Node *) lfirst(lc);
      Oid     ntype = exprType(nexpr);

      if (ntype != ptype)
        break;
    }
    if (lc == NULL)     /* got to the end of the list? */
    {
      if (which_expr)
        *which_expr = pexpr;
      return ptype;
    }
  }

  /*
   * Nope, so set up for the full algorithm.  Note that at this point, lc
   * points to the first list item with type different from pexpr's; we need
   * not re-examine any items the previous loop advanced over.
   */
  ptype = getBaseType(ptype);
  get_type_category_preferred(ptype, &pcategory, &pispreferred);

  for_each_cell(lc, exprs, lc)
  {
    Node     *nexpr = (Node *) lfirst(lc);
    Oid     ntype = getBaseType(exprType(nexpr));

    /* move on to next one if no new information... */
    if (ntype != UNKNOWNOID && ntype != ptype)
    {
      TYPCATEGORY ncategory;
      bool    nispreferred;

      get_type_category_preferred(ntype, &ncategory, &nispreferred);
      if (ptype == UNKNOWNOID)
      {
        /* so far, only unknowns so take anything... */
        pexpr = nexpr;
        ptype = ntype;
        pcategory = ncategory;
        pispreferred = nispreferred;
      }
      else if (ncategory != pcategory)
      {
        /*
         * both types in different categories? then not much hope...
         */
        if (context == NULL)
          return InvalidOid;
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
        /*------
          translator: first %s is name of a SQL construct, eg CASE */
             errmsg("%s types %s and %s cannot be matched",
                context,
                format_type_be(ptype),
                format_type_be(ntype)),
             parser_errposition(pstate, exprLocation(nexpr))));
      }
      else if (!pispreferred &&
           can_coerce_type(1, &ptype, &ntype, COERCION_IMPLICIT) &&
           !can_coerce_type(1, &ntype, &ptype, COERCION_IMPLICIT))
      {
        /*
         * take new type if can coerce to it implicitly but not the
         * other way; but if we have a preferred type, stay on it.
         */
        pexpr = nexpr;
        ptype = ntype;
        pcategory = ncategory;
        pispreferred = nispreferred;
      }
    }
  }

  /*
   * If all the inputs were UNKNOWN type --- ie, unknown-type literals ---
   * then resolve as type TEXT.  This situation comes up with constructs
   * like SELECT (CASE WHEN foo THEN 'bar' ELSE 'baz' END); SELECT 'foo'
   * UNION SELECT 'bar'; It might seem desirable to leave the construct's
   * output type as UNKNOWN, but that really doesn't work, because we'd
   * probably end up needing a runtime coercion from UNKNOWN to something
   * else, and we usually won't have it.  We need to coerce the unknown
   * literals while they are still literals, so a decision has to be made
   * now.
   */
  if (ptype == UNKNOWNOID)
    ptype = TEXTOID;

  if (which_expr)
    *which_expr = pexpr;
  return ptype;
}

/*
 * select_common_type_from_oids()
 *    Determine the common supertype of an array of type OIDs.
 *
 * This is the same logic as select_common_type(), but working from
 * an array of type OIDs not a list of expressions.  As in that function,
 * earlier entries in the array have some preference over later ones.
 * On failure, return InvalidOid if noerror is true, else throw an error.
 *
 * Caution: "failure" just means that there were inputs of different type
 * categories.  It is not guaranteed that all the inputs are coercible to the
 * selected type; caller must check that (see verify_common_type_from_oids).
 *
 * Note: neither caller will pass any UNKNOWNOID entries, so the tests
 * for that in this function are dead code.  However, they don't cost much,
 * and it seems better to keep this logic as close to select_common_type()
 * as possible.
 */
static Oid
select_common_type_from_oids(int nargs, const Oid *typeids, bool noerror)
{
  Oid     ptype;
  TYPCATEGORY pcategory;
  bool    pispreferred;
  int     i = 1;

  Assert(nargs > 0);
  ptype = typeids[0];

  /* If all input types are valid and exactly the same, pick that type. */
  if (ptype != UNKNOWNOID)
  {
    for (; i < nargs; i++)
    {
      if (typeids[i] != ptype)
        break;
    }
    if (i == nargs)
      return ptype;
  }

  /*
   * Nope, so set up for the full algorithm.  Note that at this point, we
   * can skip array entries before "i"; they are all equal to ptype.
   */
  ptype = getBaseType(ptype);
  get_type_category_preferred(ptype, &pcategory, &pispreferred);

  for (; i < nargs; i++)
  {
    Oid     ntype = getBaseType(typeids[i]);

    /* move on to next one if no new information... */
    if (ntype != UNKNOWNOID && ntype != ptype)
    {
      TYPCATEGORY ncategory;
      bool    nispreferred;

      get_type_category_preferred(ntype, &ncategory, &nispreferred);
      if (ptype == UNKNOWNOID)
      {
        /* so far, only unknowns so take anything... */
        ptype = ntype;
        pcategory = ncategory;
        pispreferred = nispreferred;
      }
      else if (ncategory != pcategory)
      {
        /*
         * both types in different categories? then not much hope...
         */
        if (noerror)
          return InvalidOid;
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("argument types %s and %s cannot be matched",
                format_type_be(ptype),
                format_type_be(ntype))));
      }
      else if (!pispreferred &&
           can_coerce_type(1, &ptype, &ntype, COERCION_IMPLICIT) &&
           !can_coerce_type(1, &ntype, &ptype, COERCION_IMPLICIT))
      {
        /*
         * take new type if can coerce to it implicitly but not the
         * other way; but if we have a preferred type, stay on it.
         */
        ptype = ntype;
        pcategory = ncategory;
        pispreferred = nispreferred;
      }
    }
  }

  /* Like select_common_type(), choose TEXT if all inputs were UNKNOWN */
  if (ptype == UNKNOWNOID)
    ptype = TEXTOID;

  return ptype;
}

/*
 * coerce_to_common_type()
 *    Coerce an expression to the given type.
 *
 * This is used following select_common_type() to coerce the individual
 * expressions to the desired type.  'context' is a phrase to use in the
 * error message if we fail to coerce.
 *
 * As with coerce_type, pstate may be NULL if no special unknown-Param
 * processing is wanted.
 */
Node *
coerce_to_common_type(ParseState *pstate, Node *node,
            Oid targetTypeId, const char *context)
{
  Oid     inputTypeId = exprType(node);

  if (inputTypeId == targetTypeId)
    return node;     /* no work */
  if (can_coerce_type(1, &inputTypeId, &targetTypeId, COERCION_IMPLICIT))
    node = coerce_type(pstate, node, inputTypeId, targetTypeId, -1,
               COERCION_IMPLICIT, COERCE_IMPLICIT_CAST, -1);
  else
    ereport(ERROR,
        (errcode(ERRCODE_CANNOT_COERCE),
    /* translator: first %s is name of a SQL construct, eg CASE */
         errmsg("%s could not convert type %s to %s",
            context,
            format_type_be(inputTypeId),
            format_type_be(targetTypeId)),
         parser_errposition(pstate, exprLocation(node))));
  return node;
}

/*
 * verify_common_type()
 *    Verify that all input types can be coerced to a proposed common type.
 *    Return true if so, false if not all coercions are possible.
 *
 * Most callers of select_common_type() don't need to do this explicitly
 * because the checks will happen while trying to convert input expressions
 * to the right type, e.g. in coerce_to_common_type().  However, if a separate
 * check step is needed to validate the applicability of the common type, call
 * this.
 */
bool
verify_common_type(Oid common_type, List *exprs)
{
  ListCell   *lc;

  foreach(lc, exprs)
  {
    Node     *nexpr = (Node *) lfirst(lc);
    Oid     ntype = exprType(nexpr);

    if (!can_coerce_type(1, &ntype, &common_type, COERCION_IMPLICIT))
      return false;
  }
  return true;
}

/*
 * verify_common_type_from_oids()
 *    As above, but work from an array of type OIDs.
 */
static bool
verify_common_type_from_oids(Oid common_type, int nargs, const Oid *typeids)
{
  for (int i = 0; i < nargs; i++)
  {
    if (!can_coerce_type(1, &typeids[i], &common_type, COERCION_IMPLICIT))
      return false;
  }
  return true;
}

/*
 * select_common_typmod()
 *    Determine the common typmod of a list of input expressions.
 *
 * common_type is the selected common type of the expressions, typically
 * computed using select_common_type().
 */
int32
select_common_typmod(ParseState *pstate, List *exprs, Oid common_type)
{
  ListCell   *lc;
  bool    first = true;
  int32   result = -1;

  foreach(lc, exprs)
  {
    Node     *expr = (Node *) lfirst(lc);

    /* Types must match */
    if (exprType(expr) != common_type)
      return -1;
    else if (first)
    {
      result = exprTypmod(expr);
      first = false;
    }
    else
    {
      /* As soon as we see a non-matching typmod, fall back to -1 */
      if (result != exprTypmod(expr))
        return -1;
    }
  }

  return result;
}

/*
 * check_generic_type_consistency()
 *    Are the actual arguments potentially compatible with a
 *    polymorphic function?
 *
 * The argument consistency rules are:
 *
 * 1) All arguments declared ANYELEMENT must have the same datatype.
 * 2) All arguments declared ANYARRAY must have the same datatype,
 *    which must be a varlena array type.
 * 3) All arguments declared ANYRANGE must be the same range type.
 *    Similarly, all arguments declared ANYMULTIRANGE must be the same
 *    multirange type; and if both of these appear, the ANYRANGE type
 *    must be the element type of the ANYMULTIRANGE type.
 * 4) If there are arguments of more than one of these polymorphic types,
 *    the array element type and/or range subtype must be the same as each
 *    other and the same as the ANYELEMENT type.
 * 5) ANYENUM is treated the same as ANYELEMENT except that if it is used
 *    (alone or in combination with plain ANYELEMENT), we add the extra
 *    condition that the ANYELEMENT type must be an enum.
 * 6) ANYNONARRAY is treated the same as ANYELEMENT except that if it is used,
 *    we add the extra condition that the ANYELEMENT type must not be an array.
 *    (This is a no-op if used in combination with ANYARRAY or ANYENUM, but
 *    is an extra restriction if not.)
 * 7) All arguments declared ANYCOMPATIBLE must be implicitly castable
 *    to a common supertype (chosen as per select_common_type's rules).
 *    ANYCOMPATIBLENONARRAY works like ANYCOMPATIBLE but also requires the
 *    common supertype to not be an array.  If there are ANYCOMPATIBLEARRAY
 *    or ANYCOMPATIBLERANGE or ANYCOMPATIBLEMULTIRANGE arguments, their element
 *    types or subtypes are included while making the choice of common supertype.
 * 8) The resolved type of ANYCOMPATIBLEARRAY arguments will be the array
 *    type over the common supertype (which might not be the same array type
 *    as any of the original arrays).
 * 9) All ANYCOMPATIBLERANGE arguments must be the exact same range type
 *    (after domain flattening), since we have no preference rule that would
 *    let us choose one over another.  Furthermore, that range's subtype
 *    must exactly match the common supertype chosen by rule 7.
 * 10) All ANYCOMPATIBLEMULTIRANGE arguments must be the exact same multirange
 *    type (after domain flattening), since we have no preference rule that
 *    would let us choose one over another.  Furthermore, if ANYCOMPATIBLERANGE
 *    also appears, that range type must be the multirange's element type;
 *    otherwise, the multirange's range's subtype must exactly match the
 *    common supertype chosen by rule 7.
 *
 * Domains over arrays match ANYARRAY, and are immediately flattened to their
 * base type.  (Thus, for example, we will consider it a match if one ANYARRAY
 * argument is a domain over int4[] while another one is just int4[].)  Also
 * notice that such a domain does *not* match ANYNONARRAY.  The same goes
 * for ANYCOMPATIBLEARRAY and ANYCOMPATIBLENONARRAY.
 *
 * Similarly, domains over ranges match ANYRANGE or ANYCOMPATIBLERANGE,
 * and are immediately flattened to their base type.  Likewise, domains
 * over multiranges match ANYMULTIRANGE or ANYCOMPATIBLEMULTIRANGE and are
 * immediately flattened to their base type.
 *
 * Note that domains aren't currently considered to match ANYENUM,
 * even if their base type would match.
 *
 * If we have UNKNOWN input (ie, an untyped literal) for any polymorphic
 * argument, assume it is okay.
 *
 * We do not ereport here, but just return false if a rule is violated.
 */
bool
check_generic_type_consistency(const Oid *actual_arg_types,
                 const Oid *declared_arg_types,
                 int nargs)
{
  Oid     elem_typeid = InvalidOid;
  Oid     array_typeid = InvalidOid;
  Oid     range_typeid = InvalidOid;
  Oid     multirange_typeid = InvalidOid;
  Oid     anycompatible_range_typeid = InvalidOid;
  Oid     anycompatible_range_typelem = InvalidOid;
  Oid     anycompatible_multirange_typeid = InvalidOid;
  Oid     anycompatible_multirange_typelem = InvalidOid;
  Oid     range_typelem = InvalidOid;
  bool    have_anynonarray = false;
  bool    have_anyenum = false;
  bool    have_anycompatible_nonarray = false;
  int     n_anycompatible_args = 0;
  Oid     anycompatible_actual_types[FUNC_MAX_ARGS];

  /*
   * Loop through the arguments to see if we have any that are polymorphic.
   * If so, require the actual types to be consistent.
   */
  Assert(nargs <= FUNC_MAX_ARGS);
  for (int j = 0; j < nargs; j++)
  {
    Oid     decl_type = declared_arg_types[j];
    Oid     actual_type = actual_arg_types[j];

    if (decl_type == ANYELEMENTOID ||
      decl_type == ANYNONARRAYOID ||
      decl_type == ANYENUMOID)
    {
      if (decl_type == ANYNONARRAYOID)
        have_anynonarray = true;
      else if (decl_type == ANYENUMOID)
        have_anyenum = true;
      if (actual_type == UNKNOWNOID)
        continue;
      if (OidIsValid(elem_typeid) && actual_type != elem_typeid)
        return false;
      elem_typeid = actual_type;
    }
    else if (decl_type == ANYARRAYOID)
    {
      if (actual_type == UNKNOWNOID)
        continue;
      actual_type = getBaseType(actual_type); /* flatten domains */
      if (OidIsValid(array_typeid) && actual_type != array_typeid)
        return false;
      array_typeid = actual_type;
    }
    else if (decl_type == ANYRANGEOID)
    {
      if (actual_type == UNKNOWNOID)
        continue;
      actual_type = getBaseType(actual_type); /* flatten domains */
      if (OidIsValid(range_typeid) && actual_type != range_typeid)
        return false;
      range_typeid = actual_type;
    }
    else if (decl_type == ANYMULTIRANGEOID)
    {
      if (actual_type == UNKNOWNOID)
        continue;
      actual_type = getBaseType(actual_type); /* flatten domains */
      if (OidIsValid(multirange_typeid) && actual_type != multirange_typeid)
        return false;
      multirange_typeid = actual_type;
    }
    else if (decl_type == ANYCOMPATIBLEOID ||
         decl_type == ANYCOMPATIBLENONARRAYOID)
    {
      if (decl_type == ANYCOMPATIBLENONARRAYOID)
        have_anycompatible_nonarray = true;
      if (actual_type == UNKNOWNOID)
        continue;
      /* collect the actual types of non-unknown COMPATIBLE args */
      anycompatible_actual_types[n_anycompatible_args++] = actual_type;
    }
    else if (decl_type == ANYCOMPATIBLEARRAYOID)
    {
      Oid     elem_type;

      if (actual_type == UNKNOWNOID)
        continue;
      actual_type = getBaseType(actual_type); /* flatten domains */
      elem_type = get_element_type(actual_type);
      if (!OidIsValid(elem_type))
        return false; /* not an array */
      /* collect the element type for common-supertype choice */
      anycompatible_actual_types[n_anycompatible_args++] = elem_type;
    }
    else if (decl_type == ANYCOMPATIBLERANGEOID)
    {
      if (actual_type == UNKNOWNOID)
        continue;
      actual_type = getBaseType(actual_type); /* flatten domains */
      if (OidIsValid(anycompatible_range_typeid))
      {
        /* All ANYCOMPATIBLERANGE arguments must be the same type */
        if (anycompatible_range_typeid != actual_type)
          return false;
      }
      else
      {
        anycompatible_range_typeid = actual_type;
        anycompatible_range_typelem = get_range_subtype(actual_type);
        if (!OidIsValid(anycompatible_range_typelem))
          return false; /* not a range type */
        /* collect the subtype for common-supertype choice */
        anycompatible_actual_types[n_anycompatible_args++] = anycompatible_range_typelem;
      }
    }
    else if (decl_type == ANYCOMPATIBLEMULTIRANGEOID)
    {
      if (actual_type == UNKNOWNOID)
        continue;
      actual_type = getBaseType(actual_type); /* flatten domains */
      if (OidIsValid(anycompatible_multirange_typeid))
      {
        /* All ANYCOMPATIBLEMULTIRANGE arguments must be the same type */
        if (anycompatible_multirange_typeid != actual_type)
          return false;
      }
      else
      {
        anycompatible_multirange_typeid = actual_type;
        anycompatible_multirange_typelem = get_multirange_range(actual_type);
        if (!OidIsValid(anycompatible_multirange_typelem))
          return false; /* not a multirange type */
        /* we'll consider the subtype below */
      }
    }
  }

  /* Get the element type based on the array type, if we have one */
  if (OidIsValid(array_typeid))
  {
    if (array_typeid == ANYARRAYOID)
    {
      /*
       * Special case for matching ANYARRAY input to an ANYARRAY
       * argument: allow it for now.  enforce_generic_type_consistency()
       * might complain later, depending on the presence of other
       * polymorphic arguments or results, but it will deliver a less
       * surprising error message than "function does not exist".
       *
       * (If you think to change this, note that can_coerce_type will
       * consider such a situation as a match, so that we might not even
       * get here.)
       */
    }
    else
    {
      Oid     array_typelem;

      array_typelem = get_element_type(array_typeid);
      if (!OidIsValid(array_typelem))
        return false; /* should be an array, but isn't */

      if (!OidIsValid(elem_typeid))
      {
        /*
         * if we don't have an element type yet, use the one we just
         * got
         */
        elem_typeid = array_typelem;
      }
      else if (array_typelem != elem_typeid)
      {
        /* otherwise, they better match */
        return false;
      }
    }
  }

  /* Deduce range type from multirange type, or check that they agree */
  if (OidIsValid(multirange_typeid))
  {
    Oid     multirange_typelem;

    multirange_typelem = get_multirange_range(multirange_typeid);
    if (!OidIsValid(multirange_typelem))
      return false;   /* should be a multirange, but isn't */

    if (!OidIsValid(range_typeid))
    {
      /* If we don't have a range type yet, use the one we just got */
      range_typeid = multirange_typelem;
      range_typelem = get_range_subtype(multirange_typelem);
      if (!OidIsValid(range_typelem))
        return false; /* should be a range, but isn't */
    }
    else if (multirange_typelem != range_typeid)
    {
      /* otherwise, they better match */
      return false;
    }
  }

  /* Get the element type based on the range type, if we have one */
  if (OidIsValid(range_typeid))
  {
    range_typelem = get_range_subtype(range_typeid);
    if (!OidIsValid(range_typelem))
      return false;   /* should be a range, but isn't */

    if (!OidIsValid(elem_typeid))
    {
      /*
       * If we don't have an element type yet, use the one we just got
       */
      elem_typeid = range_typelem;
    }
    else if (range_typelem != elem_typeid)
    {
      /* otherwise, they better match */
      return false;
    }
  }

  if (have_anynonarray)
  {
    /* require the element type to not be an array or domain over array */
    if (type_is_array_domain(elem_typeid))
      return false;
  }

  if (have_anyenum)
  {
    /* require the element type to be an enum */
    if (!type_is_enum(elem_typeid))
      return false;
  }

  /* Deduce range type from multirange type, or check that they agree */
  if (OidIsValid(anycompatible_multirange_typeid))
  {
    if (OidIsValid(anycompatible_range_typeid))
    {
      if (anycompatible_multirange_typelem !=
        anycompatible_range_typeid)
        return false;
    }
    else
    {
      anycompatible_range_typeid = anycompatible_multirange_typelem;
      anycompatible_range_typelem = get_range_subtype(anycompatible_range_typeid);
      if (!OidIsValid(anycompatible_range_typelem))
        return false; /* not a range type */
      /* collect the subtype for common-supertype choice */
      anycompatible_actual_types[n_anycompatible_args++] =
        anycompatible_range_typelem;
    }
  }

  /* Check matching of ANYCOMPATIBLE-family arguments, if any */
  if (n_anycompatible_args > 0)
  {
    Oid     anycompatible_typeid;

    anycompatible_typeid =
      select_common_type_from_oids(n_anycompatible_args,
                     anycompatible_actual_types,
                     true);

    if (!OidIsValid(anycompatible_typeid))
      return false;   /* there's definitely no common supertype */

    /* We have to verify that the selected type actually works */
    if (!verify_common_type_from_oids(anycompatible_typeid,
                      n_anycompatible_args,
                      anycompatible_actual_types))
      return false;

    if (have_anycompatible_nonarray)
    {
      /*
       * require the anycompatible type to not be an array or domain
       * over array
       */
      if (type_is_array_domain(anycompatible_typeid))
        return false;
    }

    /*
     * The anycompatible type must exactly match the range element type,
     * if we were able to identify one. This checks compatibility for
     * anycompatiblemultirange too since that also sets
     * anycompatible_range_typelem above.
     */
    if (OidIsValid(anycompatible_range_typelem) &&
      anycompatible_range_typelem != anycompatible_typeid)
      return false;
  }

  /* Looks valid */
  return true;
}

/*
 * enforce_generic_type_consistency()
 *    Make sure a polymorphic function is legally callable, and
 *    deduce actual argument and result types.
 *
 * If any polymorphic pseudotype is used in a function's arguments or
 * return type, we make sure the actual data types are consistent with
 * each other.  The argument consistency rules are shown above for
 * check_generic_type_consistency().
 *
 * If we have UNKNOWN input (ie, an untyped literal) for any polymorphic
 * argument, we attempt to deduce the actual type it should have.  If
 * successful, we alter that position of declared_arg_types[] so that
 * make_fn_arguments will coerce the literal to the right thing.
 *
 * If we have polymorphic arguments of the ANYCOMPATIBLE family,
 * we similarly alter declared_arg_types[] entries to show the resolved
 * common supertype, so that make_fn_arguments will coerce the actual
 * arguments to the proper type.
 *
 * Rules are applied to the function's return type (possibly altering it)
 * if it is declared as a polymorphic type and there is at least one
 * polymorphic argument type:
 *
 * 1) If return type is ANYELEMENT, and any argument is ANYELEMENT, use the
 *    argument's actual type as the function's return type.
 * 2) If return type is ANYARRAY, and any argument is ANYARRAY, use the
 *    argument's actual type as the function's return type.
 * 3) Similarly, if return type is ANYRANGE or ANYMULTIRANGE, and any
 *    argument is ANYRANGE or ANYMULTIRANGE, use that argument's actual type
 *    (or the corresponding range or multirange type) as the function's return
 *    type.
 * 4) Otherwise, if return type is ANYELEMENT or ANYARRAY, and there is
 *    at least one ANYELEMENT, ANYARRAY, ANYRANGE, or ANYMULTIRANGE input,
 *    deduce the return type from those inputs, or throw error if we can't.
 * 5) Otherwise, if return type is ANYRANGE or ANYMULTIRANGE, throw error.
 *    (We have no way to select a specific range type if the arguments don't
 *    include ANYRANGE or ANYMULTIRANGE.)
 * 6) ANYENUM is treated the same as ANYELEMENT except that if it is used
 *    (alone or in combination with plain ANYELEMENT), we add the extra
 *    condition that the ANYELEMENT type must be an enum.
 * 7) ANYNONARRAY is treated the same as ANYELEMENT except that if it is used,
 *    we add the extra condition that the ANYELEMENT type must not be an array.
 *    (This is a no-op if used in combination with ANYARRAY or ANYENUM, but
 *    is an extra restriction if not.)
 * 8) ANYCOMPATIBLE, ANYCOMPATIBLEARRAY, and ANYCOMPATIBLENONARRAY are handled
 *    by resolving the common supertype of those arguments (or their element
 *    types, for array inputs), and then coercing all those arguments to the
 *    common supertype, or the array type over the common supertype for
 *    ANYCOMPATIBLEARRAY.
 * 9) For ANYCOMPATIBLERANGE and ANYCOMPATIBLEMULTIRANGE, there must be at
 *    least one non-UNKNOWN input matching those arguments, and all such
 *    inputs must be the same range type (or its multirange type, as
 *    appropriate), since we cannot deduce a range type from non-range types.
 *    Furthermore, the range type's subtype is included while choosing the
 *    common supertype for ANYCOMPATIBLE et al, and it must exactly match
 *    that common supertype.
 *
 * Domains over arrays or ranges match ANYARRAY or ANYRANGE arguments,
 * respectively, and are immediately flattened to their base type.  (In
 * particular, if the return type is also ANYARRAY or ANYRANGE, we'll set
 * it to the base type not the domain type.)  The same is true for
 * ANYMULTIRANGE, ANYCOMPATIBLEARRAY, ANYCOMPATIBLERANGE, and
 * ANYCOMPATIBLEMULTIRANGE.
 *
 * When allow_poly is false, we are not expecting any of the actual_arg_types
 * to be polymorphic, and we should not return a polymorphic result type
 * either.  When allow_poly is true, it is okay to have polymorphic "actual"
 * arg types, and we can return a matching polymorphic type as the result.
 * (This case is currently used only to check compatibility of an aggregate's
 * declaration with the underlying transfn.)
 *
 * A special case is that we could see ANYARRAY as an actual_arg_type even
 * when allow_poly is false (this is possible only because pg_statistic has
 * columns shown as anyarray in the catalogs).  We allow this to match a
 * declared ANYARRAY argument, but only if there is no other polymorphic
 * argument that we would need to match it with, and no need to determine
 * the element type to infer the result type.  Note this means that functions
 * taking ANYARRAY had better behave sanely if applied to the pg_statistic
 * columns; they can't just assume that successive inputs are of the same
 * actual element type.  There is no similar logic for ANYCOMPATIBLEARRAY;
 * there isn't a need for it since there are no catalog columns of that type,
 * so we won't see it as input.  We could consider matching an actual ANYARRAY
 * input to an ANYCOMPATIBLEARRAY argument, but at present that seems useless
 * as well, since there's no value in using ANYCOMPATIBLEARRAY unless there's
 * at least one other ANYCOMPATIBLE-family argument or result.
 *
 * Also, if there are no arguments declared to be of polymorphic types,
 * we'll return the rettype unmodified even if it's polymorphic.  This should
 * never occur for user-declared functions, because CREATE FUNCTION prevents
 * it.  But it does happen for some built-in functions, such as array_in().
 */
Oid
enforce_generic_type_consistency(const Oid *actual_arg_types,
                 Oid *declared_arg_types,
                 int nargs,
                 Oid rettype,
                 bool allow_poly)
{
  bool    have_poly_anycompatible = false;
  bool    have_poly_unknowns = false;
  Oid     elem_typeid = InvalidOid;
  Oid     array_typeid = InvalidOid;
  Oid     range_typeid = InvalidOid;
  Oid     multirange_typeid = InvalidOid;
  Oid     anycompatible_typeid = InvalidOid;
  Oid     anycompatible_array_typeid = InvalidOid;
  Oid     anycompatible_range_typeid = InvalidOid;
  Oid     anycompatible_range_typelem = InvalidOid;
  Oid     anycompatible_multirange_typeid = InvalidOid;
  Oid     anycompatible_multirange_typelem = InvalidOid;
  bool    have_anynonarray = (rettype == ANYNONARRAYOID);
  bool    have_anyenum = (rettype == ANYENUMOID);
  bool    have_anymultirange = (rettype == ANYMULTIRANGEOID);
  bool    have_anycompatible_nonarray = (rettype == ANYCOMPATIBLENONARRAYOID);
  bool    have_anycompatible_array = (rettype == ANYCOMPATIBLEARRAYOID);
  bool    have_anycompatible_range = (rettype == ANYCOMPATIBLERANGEOID);
  bool    have_anycompatible_multirange = (rettype == ANYCOMPATIBLEMULTIRANGEOID);
  int     n_poly_args = 0;  /* this counts all family-1 arguments */
  int     n_anycompatible_args = 0; /* this counts only non-unknowns */
  Oid     anycompatible_actual_types[FUNC_MAX_ARGS];

  /*
   * Loop through the arguments to see if we have any that are polymorphic.
   * If so, require the actual types to be consistent.
   */
  Assert(nargs <= FUNC_MAX_ARGS);
  for (int j = 0; j < nargs; j++)
  {
    Oid     decl_type = declared_arg_types[j];
    Oid     actual_type = actual_arg_types[j];

    if (decl_type == ANYELEMENTOID ||
      decl_type == ANYNONARRAYOID ||
      decl_type == ANYENUMOID)
    {
      n_poly_args++;
      if (decl_type == ANYNONARRAYOID)
        have_anynonarray = true;
      else if (decl_type == ANYENUMOID)
        have_anyenum = true;
      if (actual_type == UNKNOWNOID)
      {
        have_poly_unknowns = true;
        continue;
      }
      if (allow_poly && decl_type == actual_type)
        continue;   /* no new information here */
      if (OidIsValid(elem_typeid) && actual_type != elem_typeid)
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("arguments declared \"%s\" are not all alike", "anyelement"),
             errdetail("%s versus %s",
                   format_type_be(elem_typeid),
                   format_type_be(actual_type))));
      elem_typeid = actual_type;
    }
    else if (decl_type == ANYARRAYOID)
    {
      n_poly_args++;
      if (actual_type == UNKNOWNOID)
      {
        have_poly_unknowns = true;
        continue;
      }
      if (allow_poly && decl_type == actual_type)
        continue;   /* no new information here */
      actual_type = getBaseType(actual_type); /* flatten domains */
      if (OidIsValid(array_typeid) && actual_type != array_typeid)
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("arguments declared \"%s\" are not all alike", "anyarray"),
             errdetail("%s versus %s",
                   format_type_be(array_typeid),
                   format_type_be(actual_type))));
      array_typeid = actual_type;
    }
    else if (decl_type == ANYRANGEOID)
    {
      n_poly_args++;
      if (actual_type == UNKNOWNOID)
      {
        have_poly_unknowns = true;
        continue;
      }
      if (allow_poly && decl_type == actual_type)
        continue;   /* no new information here */
      actual_type = getBaseType(actual_type); /* flatten domains */
      if (OidIsValid(range_typeid) && actual_type != range_typeid)
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("arguments declared \"%s\" are not all alike", "anyrange"),
             errdetail("%s versus %s",
                   format_type_be(range_typeid),
                   format_type_be(actual_type))));
      range_typeid = actual_type;
    }
    else if (decl_type == ANYMULTIRANGEOID)
    {
      n_poly_args++;
      have_anymultirange = true;
      if (actual_type == UNKNOWNOID)
      {
        have_poly_unknowns = true;
        continue;
      }
      if (allow_poly && decl_type == actual_type)
        continue;   /* no new information here */
      actual_type = getBaseType(actual_type); /* flatten domains */
      if (OidIsValid(multirange_typeid) && actual_type != multirange_typeid)
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("arguments declared \"%s\" are not all alike", "anymultirange"),
             errdetail("%s versus %s",
                   format_type_be(multirange_typeid),
                   format_type_be(actual_type))));
      multirange_typeid = actual_type;
    }
    else if (decl_type == ANYCOMPATIBLEOID ||
         decl_type == ANYCOMPATIBLENONARRAYOID)
    {
      have_poly_anycompatible = true;
      if (decl_type == ANYCOMPATIBLENONARRAYOID)
        have_anycompatible_nonarray = true;
      if (actual_type == UNKNOWNOID)
        continue;
      if (allow_poly && decl_type == actual_type)
        continue;   /* no new information here */
      /* collect the actual types of non-unknown COMPATIBLE args */
      anycompatible_actual_types[n_anycompatible_args++] = actual_type;
    }
    else if (decl_type == ANYCOMPATIBLEARRAYOID)
    {
      Oid     anycompatible_elem_type;

      have_poly_anycompatible = true;
      have_anycompatible_array = true;
      if (actual_type == UNKNOWNOID)
        continue;
      if (allow_poly && decl_type == actual_type)
        continue;   /* no new information here */
      actual_type = getBaseType(actual_type); /* flatten domains */
      anycompatible_elem_type = get_element_type(actual_type);
      if (!OidIsValid(anycompatible_elem_type))
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("argument declared %s is not an array but type %s",
                "anycompatiblearray",
                format_type_be(actual_type))));
      /* collect the element type for common-supertype choice */
      anycompatible_actual_types[n_anycompatible_args++] = anycompatible_elem_type;
    }
    else if (decl_type == ANYCOMPATIBLERANGEOID)
    {
      have_poly_anycompatible = true;
      have_anycompatible_range = true;
      if (actual_type == UNKNOWNOID)
        continue;
      if (allow_poly && decl_type == actual_type)
        continue;   /* no new information here */
      actual_type = getBaseType(actual_type); /* flatten domains */
      if (OidIsValid(anycompatible_range_typeid))
      {
        /* All ANYCOMPATIBLERANGE arguments must be the same type */
        if (anycompatible_range_typeid != actual_type)
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("arguments declared \"%s\" are not all alike", "anycompatiblerange"),
               errdetail("%s versus %s",
                     format_type_be(anycompatible_range_typeid),
                     format_type_be(actual_type))));
      }
      else
      {
        anycompatible_range_typeid = actual_type;
        anycompatible_range_typelem = get_range_subtype(actual_type);
        if (!OidIsValid(anycompatible_range_typelem))
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("argument declared %s is not a range type but type %s",
                  "anycompatiblerange",
                  format_type_be(actual_type))));
        /* collect the subtype for common-supertype choice */
        anycompatible_actual_types[n_anycompatible_args++] = anycompatible_range_typelem;
      }
    }
    else if (decl_type == ANYCOMPATIBLEMULTIRANGEOID)
    {
      have_poly_anycompatible = true;
      have_anycompatible_multirange = true;
      if (actual_type == UNKNOWNOID)
        continue;
      if (allow_poly && decl_type == actual_type)
        continue;   /* no new information here */
      actual_type = getBaseType(actual_type); /* flatten domains */
      if (OidIsValid(anycompatible_multirange_typeid))
      {
        /* All ANYCOMPATIBLEMULTIRANGE arguments must be the same type */
        if (anycompatible_multirange_typeid != actual_type)
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("arguments declared \"%s\" are not all alike", "anycompatiblemultirange"),
               errdetail("%s versus %s",
                     format_type_be(anycompatible_multirange_typeid),
                     format_type_be(actual_type))));
      }
      else
      {
        anycompatible_multirange_typeid = actual_type;
        anycompatible_multirange_typelem = get_multirange_range(actual_type);
        if (!OidIsValid(anycompatible_multirange_typelem))
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("argument declared %s is not a multirange type but type %s",
                  "anycompatiblemultirange",
                  format_type_be(actual_type))));
        /* we'll consider the subtype below */
      }
    }
  }

  /*
   * Fast Track: if none of the arguments are polymorphic, return the
   * unmodified rettype.  Not our job to resolve it if it's polymorphic.
   */
  if (n_poly_args == 0 && !have_poly_anycompatible)
    return rettype;

  /* Check matching of family-1 polymorphic arguments, if any */
  if (n_poly_args)
  {
    /* Get the element type based on the array type, if we have one */
    if (OidIsValid(array_typeid))
    {
      Oid     array_typelem;

      if (array_typeid == ANYARRAYOID)
      {
        /*
         * Special case for matching ANYARRAY input to an ANYARRAY
         * argument: allow it iff no other arguments are family-1
         * polymorphics (otherwise we couldn't be sure whether the
         * array element type matches up) and the result type doesn't
         * require us to infer a specific element type.
         */
        if (n_poly_args != 1 ||
          (rettype != ANYARRAYOID &&
           IsPolymorphicTypeFamily1(rettype)))
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("cannot determine element type of \"anyarray\" argument")));
        array_typelem = ANYELEMENTOID;
      }
      else
      {
        array_typelem = get_element_type(array_typeid);
        if (!OidIsValid(array_typelem))
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("argument declared %s is not an array but type %s",
                  "anyarray", format_type_be(array_typeid))));
      }

      if (!OidIsValid(elem_typeid))
      {
        /*
         * if we don't have an element type yet, use the one we just
         * got
         */
        elem_typeid = array_typelem;
      }
      else if (array_typelem != elem_typeid)
      {
        /* otherwise, they better match */
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("argument declared %s is not consistent with argument declared %s",
                "anyarray", "anyelement"),
             errdetail("%s versus %s",
                   format_type_be(array_typeid),
                   format_type_be(elem_typeid))));
      }
    }

    /* Deduce range type from multirange type, or vice versa */
    if (OidIsValid(multirange_typeid))
    {
      Oid     multirange_typelem;

      multirange_typelem = get_multirange_range(multirange_typeid);
      if (!OidIsValid(multirange_typelem))
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("argument declared %s is not a multirange type but type %s",
                "anymultirange",
                format_type_be(multirange_typeid))));

      if (!OidIsValid(range_typeid))
      {
        /* if we don't have a range type yet, use the one we just got */
        range_typeid = multirange_typelem;
      }
      else if (multirange_typelem != range_typeid)
      {
        /* otherwise, they better match */
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("argument declared %s is not consistent with argument declared %s",
                "anymultirange", "anyrange"),
             errdetail("%s versus %s",
                   format_type_be(multirange_typeid),
                   format_type_be(range_typeid))));
      }
    }
    else if (have_anymultirange && OidIsValid(range_typeid))
    {
      multirange_typeid = get_range_multirange(range_typeid);
      /* We'll complain below if that didn't work */
    }

    /* Get the element type based on the range type, if we have one */
    if (OidIsValid(range_typeid))
    {
      Oid     range_typelem;

      range_typelem = get_range_subtype(range_typeid);
      if (!OidIsValid(range_typelem))
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("argument declared %s is not a range type but type %s",
                "anyrange",
                format_type_be(range_typeid))));

      if (!OidIsValid(elem_typeid))
      {
        /*
         * if we don't have an element type yet, use the one we just
         * got
         */
        elem_typeid = range_typelem;
      }
      else if (range_typelem != elem_typeid)
      {
        /* otherwise, they better match */
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("argument declared %s is not consistent with argument declared %s",
                "anyrange", "anyelement"),
             errdetail("%s versus %s",
                   format_type_be(range_typeid),
                   format_type_be(elem_typeid))));
      }
    }

    if (!OidIsValid(elem_typeid))
    {
      if (allow_poly)
      {
        elem_typeid = ANYELEMENTOID;
        array_typeid = ANYARRAYOID;
        range_typeid = ANYRANGEOID;
        multirange_typeid = ANYMULTIRANGEOID;
      }
      else
      {
        /*
         * Only way to get here is if all the family-1 polymorphic
         * arguments have UNKNOWN inputs.
         */
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("could not determine polymorphic type because input has type %s",
                "unknown")));
      }
    }

    if (have_anynonarray && elem_typeid != ANYELEMENTOID)
    {
      /*
       * require the element type to not be an array or domain over
       * array
       */
      if (type_is_array_domain(elem_typeid))
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("type matched to anynonarray is an array type: %s",
                format_type_be(elem_typeid))));
    }

    if (have_anyenum && elem_typeid != ANYELEMENTOID)
    {
      /* require the element type to be an enum */
      if (!type_is_enum(elem_typeid))
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("type matched to anyenum is not an enum type: %s",
                format_type_be(elem_typeid))));
    }
  }

  /* Check matching of family-2 polymorphic arguments, if any */
  if (have_poly_anycompatible)
  {
    /* Deduce range type from multirange type, or vice versa */
    if (OidIsValid(anycompatible_multirange_typeid))
    {
      if (OidIsValid(anycompatible_range_typeid))
      {
        if (anycompatible_multirange_typelem !=
          anycompatible_range_typeid)
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("argument declared %s is not consistent with argument declared %s",
                  "anycompatiblemultirange",
                  "anycompatiblerange"),
               errdetail("%s versus %s",
                     format_type_be(anycompatible_multirange_typeid),
                     format_type_be(anycompatible_range_typeid))));
      }
      else
      {
        anycompatible_range_typeid = anycompatible_multirange_typelem;
        anycompatible_range_typelem = get_range_subtype(anycompatible_range_typeid);
        if (!OidIsValid(anycompatible_range_typelem))
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("argument declared %s is not a multirange type but type %s",
                  "anycompatiblemultirange",
                  format_type_be(anycompatible_multirange_typeid))));
        /* this enables element type matching check below */
        have_anycompatible_range = true;
        /* collect the subtype for common-supertype choice */
        anycompatible_actual_types[n_anycompatible_args++] =
          anycompatible_range_typelem;
      }
    }
    else if (have_anycompatible_multirange &&
         OidIsValid(anycompatible_range_typeid))
    {
      anycompatible_multirange_typeid = get_range_multirange(anycompatible_range_typeid);
      /* We'll complain below if that didn't work */
    }

    if (n_anycompatible_args > 0)
    {
      anycompatible_typeid =
        select_common_type_from_oids(n_anycompatible_args,
                       anycompatible_actual_types,
                       false);

      /* We have to verify that the selected type actually works */
      if (!verify_common_type_from_oids(anycompatible_typeid,
                        n_anycompatible_args,
                        anycompatible_actual_types))
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("arguments of anycompatible family cannot be cast to a common type")));

      if (have_anycompatible_array)
      {
        anycompatible_array_typeid = get_array_type(anycompatible_typeid);
        if (!OidIsValid(anycompatible_array_typeid))
          ereport(ERROR,
              (errcode(ERRCODE_UNDEFINED_OBJECT),
               errmsg("could not find array type for data type %s",
                  format_type_be(anycompatible_typeid))));
      }

      if (have_anycompatible_range)
      {
        /* we can't infer a range type from the others */
        if (!OidIsValid(anycompatible_range_typeid))
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("could not determine polymorphic type %s because input has type %s",
                  "anycompatiblerange", "unknown")));

        /*
         * the anycompatible type must exactly match the range element
         * type
         */
        if (anycompatible_range_typelem != anycompatible_typeid)
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("anycompatiblerange type %s does not match anycompatible type %s",
                  format_type_be(anycompatible_range_typeid),
                  format_type_be(anycompatible_typeid))));
      }

      if (have_anycompatible_multirange)
      {
        /* we can't infer a multirange type from the others */
        if (!OidIsValid(anycompatible_multirange_typeid))
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("could not determine polymorphic type %s because input has type %s",
                  "anycompatiblemultirange", "unknown")));

        /*
         * the anycompatible type must exactly match the multirange
         * element type
         */
        if (anycompatible_range_typelem != anycompatible_typeid)
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("anycompatiblemultirange type %s does not match anycompatible type %s",
                  format_type_be(anycompatible_multirange_typeid),
                  format_type_be(anycompatible_typeid))));
      }

      if (have_anycompatible_nonarray)
      {
        /*
         * require the element type to not be an array or domain over
         * array
         */
        if (type_is_array_domain(anycompatible_typeid))
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("type matched to anycompatiblenonarray is an array type: %s",
                  format_type_be(anycompatible_typeid))));
      }
    }
    else
    {
      if (allow_poly)
      {
        anycompatible_typeid = ANYCOMPATIBLEOID;
        anycompatible_array_typeid = ANYCOMPATIBLEARRAYOID;
        anycompatible_range_typeid = ANYCOMPATIBLERANGEOID;
        anycompatible_multirange_typeid = ANYCOMPATIBLEMULTIRANGEOID;
      }
      else
      {
        /*
         * Only way to get here is if all the family-2 polymorphic
         * arguments have UNKNOWN inputs.  Resolve to TEXT as
         * select_common_type() would do.  That doesn't license us to
         * use TEXTRANGE or TEXTMULTIRANGE, though.
         */
        anycompatible_typeid = TEXTOID;
        anycompatible_array_typeid = TEXTARRAYOID;
        if (have_anycompatible_range)
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("could not determine polymorphic type %s because input has type %s",
                  "anycompatiblerange", "unknown")));
        if (have_anycompatible_multirange)
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("could not determine polymorphic type %s because input has type %s",
                  "anycompatiblemultirange", "unknown")));
      }
    }

    /* replace family-2 polymorphic types by selected types */
    for (int j = 0; j < nargs; j++)
    {
      Oid     decl_type = declared_arg_types[j];

      if (decl_type == ANYCOMPATIBLEOID ||
        decl_type == ANYCOMPATIBLENONARRAYOID)
        declared_arg_types[j] = anycompatible_typeid;
      else if (decl_type == ANYCOMPATIBLEARRAYOID)
        declared_arg_types[j] = anycompatible_array_typeid;
      else if (decl_type == ANYCOMPATIBLERANGEOID)
        declared_arg_types[j] = anycompatible_range_typeid;
      else if (decl_type == ANYCOMPATIBLEMULTIRANGEOID)
        declared_arg_types[j] = anycompatible_multirange_typeid;
    }
  }

  /*
   * If we had any UNKNOWN inputs for family-1 polymorphic arguments,
   * re-scan to assign correct types to them.
   *
   * Note: we don't have to consider unknown inputs that were matched to
   * family-2 polymorphic arguments, because we forcibly updated their
   * declared_arg_types[] positions just above.
   */
  if (have_poly_unknowns)
  {
    for (int j = 0; j < nargs; j++)
    {
      Oid     decl_type = declared_arg_types[j];
      Oid     actual_type = actual_arg_types[j];

      if (actual_type != UNKNOWNOID)
        continue;

      if (decl_type == ANYELEMENTOID ||
        decl_type == ANYNONARRAYOID ||
        decl_type == ANYENUMOID)
        declared_arg_types[j] = elem_typeid;
      else if (decl_type == ANYARRAYOID)
      {
        if (!OidIsValid(array_typeid))
        {
          array_typeid = get_array_type(elem_typeid);
          if (!OidIsValid(array_typeid))
            ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("could not find array type for data type %s",
                    format_type_be(elem_typeid))));
        }
        declared_arg_types[j] = array_typeid;
      }
      else if (decl_type == ANYRANGEOID)
      {
        if (!OidIsValid(range_typeid))
        {
          /* we can't infer a range type from the others */
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("could not determine polymorphic type %s because input has type %s",
                  "anyrange", "unknown")));
        }
        declared_arg_types[j] = range_typeid;
      }
      else if (decl_type == ANYMULTIRANGEOID)
      {
        if (!OidIsValid(multirange_typeid))
        {
          /* we can't infer a multirange type from the others */
          ereport(ERROR,
              (errcode(ERRCODE_DATATYPE_MISMATCH),
               errmsg("could not determine polymorphic type %s because input has type %s",
                  "anymultirange", "unknown")));
        }
        declared_arg_types[j] = multirange_typeid;
      }
    }
  }

  /* if we return ANYELEMENT use the appropriate argument type */
  if (rettype == ANYELEMENTOID ||
    rettype == ANYNONARRAYOID ||
    rettype == ANYENUMOID)
    return elem_typeid;

  /* if we return ANYARRAY use the appropriate argument type */
  if (rettype == ANYARRAYOID)
  {
    if (!OidIsValid(array_typeid))
    {
      array_typeid = get_array_type(elem_typeid);
      if (!OidIsValid(array_typeid))
        ereport(ERROR,
            (errcode(ERRCODE_UNDEFINED_OBJECT),
             errmsg("could not find array type for data type %s",
                format_type_be(elem_typeid))));
    }
    return array_typeid;
  }

  /* if we return ANYRANGE use the appropriate argument type */
  if (rettype == ANYRANGEOID)
  {
    /* this error is unreachable if the function signature is valid: */
    if (!OidIsValid(range_typeid))
      ereport(ERROR,
          (errcode(ERRCODE_DATATYPE_MISMATCH),
           errmsg_internal("could not determine polymorphic type %s because input has type %s",
                   "anyrange", "unknown")));
    return range_typeid;
  }

  /* if we return ANYMULTIRANGE use the appropriate argument type */
  if (rettype == ANYMULTIRANGEOID)
  {
    /* this error is unreachable if the function signature is valid: */
    if (!OidIsValid(multirange_typeid))
      ereport(ERROR,
          (errcode(ERRCODE_DATATYPE_MISMATCH),
           errmsg_internal("could not determine polymorphic type %s because input has type %s",
                   "anymultirange", "unknown")));
    return multirange_typeid;
  }

  /* if we return ANYCOMPATIBLE use the appropriate type */
  if (rettype == ANYCOMPATIBLEOID ||
    rettype == ANYCOMPATIBLENONARRAYOID)
  {
    /* this error is unreachable if the function signature is valid: */
    if (!OidIsValid(anycompatible_typeid))
      ereport(ERROR,
          (errcode(ERRCODE_DATATYPE_MISMATCH),
           errmsg_internal("could not identify anycompatible type")));
    return anycompatible_typeid;
  }

  /* if we return ANYCOMPATIBLEARRAY use the appropriate type */
  if (rettype == ANYCOMPATIBLEARRAYOID)
  {
    /* this error is unreachable if the function signature is valid: */
    if (!OidIsValid(anycompatible_array_typeid))
      ereport(ERROR,
          (errcode(ERRCODE_DATATYPE_MISMATCH),
           errmsg_internal("could not identify anycompatiblearray type")));
    return anycompatible_array_typeid;
  }

  /* if we return ANYCOMPATIBLERANGE use the appropriate argument type */
  if (rettype == ANYCOMPATIBLERANGEOID)
  {
    /* this error is unreachable if the function signature is valid: */
    if (!OidIsValid(anycompatible_range_typeid))
      ereport(ERROR,
          (errcode(ERRCODE_DATATYPE_MISMATCH),
           errmsg_internal("could not identify anycompatiblerange type")));
    return anycompatible_range_typeid;
  }

  /* if we return ANYCOMPATIBLEMULTIRANGE use the appropriate argument type */
  if (rettype == ANYCOMPATIBLEMULTIRANGEOID)
  {
    /* this error is unreachable if the function signature is valid: */
    if (!OidIsValid(anycompatible_multirange_typeid))
      ereport(ERROR,
          (errcode(ERRCODE_DATATYPE_MISMATCH),
           errmsg_internal("could not identify anycompatiblemultirange type")));
    return anycompatible_multirange_typeid;
  }

  /* we don't return a generic type; send back the original return type */
  return rettype;
}

/*
 * check_valid_polymorphic_signature()
 *    Is a proposed function signature valid per polymorphism rules?
 *
 * Returns NULL if the signature is valid (either ret_type is not polymorphic,
 * or it can be deduced from the given declared argument types).  Otherwise,
 * returns a palloc'd, already translated errdetail string saying why not.
 */
char *
check_valid_polymorphic_signature(Oid ret_type,
                  const Oid *declared_arg_types,
                  int nargs)
{
  if (ret_type == ANYRANGEOID || ret_type == ANYMULTIRANGEOID)
  {
    /*
     * ANYRANGE and ANYMULTIRANGE require an ANYRANGE or ANYMULTIRANGE
     * input, else we can't tell which of several range types with the
     * same element type to use.
     */
    for (int i = 0; i < nargs; i++)
    {
      if (declared_arg_types[i] == ANYRANGEOID ||
        declared_arg_types[i] == ANYMULTIRANGEOID)
        return NULL; /* OK */
    }
    return psprintf(_("A result of type %s requires at least one input of type anyrange or anymultirange."),
            format_type_be(ret_type));
  }
  else if (ret_type == ANYCOMPATIBLERANGEOID || ret_type == ANYCOMPATIBLEMULTIRANGEOID)
  {
    /*
     * ANYCOMPATIBLERANGE and ANYCOMPATIBLEMULTIRANGE require an
     * ANYCOMPATIBLERANGE or ANYCOMPATIBLEMULTIRANGE input, else we can't
     * tell which of several range types with the same element type to
     * use.
     */
    for (int i = 0; i < nargs; i++)
    {
      if (declared_arg_types[i] == ANYCOMPATIBLERANGEOID ||
        declared_arg_types[i] == ANYCOMPATIBLEMULTIRANGEOID)
        return NULL; /* OK */
    }
    return psprintf(_("A result of type %s requires at least one input of type anycompatiblerange or anycompatiblemultirange."),
            format_type_be(ret_type));
  }
  else if (IsPolymorphicTypeFamily1(ret_type))
  {
    /* Otherwise, any family-1 type can be deduced from any other */
    for (int i = 0; i < nargs; i++)
    {
      if (IsPolymorphicTypeFamily1(declared_arg_types[i]))
        return NULL; /* OK */
    }
    /* Keep this list in sync with IsPolymorphicTypeFamily1! */
    return psprintf(_("A result of type %s requires at least one input of type anyelement, anyarray, anynonarray, anyenum, anyrange, or anymultirange."),
            format_type_be(ret_type));
  }
  else if (IsPolymorphicTypeFamily2(ret_type))
  {
    /* Otherwise, any family-2 type can be deduced from any other */
    for (int i = 0; i < nargs; i++)
    {
      if (IsPolymorphicTypeFamily2(declared_arg_types[i]))
        return NULL; /* OK */
    }
    /* Keep this list in sync with IsPolymorphicTypeFamily2! */
    return psprintf(_("A result of type %s requires at least one input of type anycompatible, anycompatiblearray, anycompatiblenonarray, anycompatiblerange, or anycompatiblemultirange."),
            format_type_be(ret_type));
  }
  else
    return NULL;     /* OK, ret_type is not polymorphic */
}

/*
 * check_valid_internal_signature()
 *    Is a proposed function signature valid per INTERNAL safety rules?
 *
 * Returns NULL if OK, or a suitable error message if ret_type is INTERNAL but
 * none of the declared arg types are.  (It's unsafe to create such a function
 * since it would allow invocation of INTERNAL-consuming functions directly
 * from SQL.)  It's overkill to return the error detail message, since there
 * is only one possibility, but we do it like this to keep the API similar to
 * check_valid_polymorphic_signature().
 */
char *
check_valid_internal_signature(Oid ret_type,
                 const Oid *declared_arg_types,
                 int nargs)
{
  if (ret_type == INTERNALOID)
  {
    for (int i = 0; i < nargs; i++)
    {
      if (declared_arg_types[i] == ret_type)
        return NULL; /* OK */
    }
    return pstrdup(_("A result of type internal requires at least one input of type internal."));
  }
  else
    return NULL;     /* OK, ret_type is not INTERNAL */
}


/*
 * TypeCategory()
 *    Assign a category to the specified type OID.
 *
 * NB: this must not return TYPCATEGORY_INVALID.
 */
TYPCATEGORY
TypeCategory(Oid type)
{
  char    typcategory;
  bool    typispreferred;

  get_type_category_preferred(type, &typcategory, &typispreferred);
  Assert(typcategory != TYPCATEGORY_INVALID);
  return (TYPCATEGORY) typcategory;
}


/*
 * IsPreferredType()
 *    Check if this type is a preferred type for the given category.
 *
 * If category is TYPCATEGORY_INVALID, then we'll return true for preferred
 * types of any category; otherwise, only for preferred types of that
 * category.
 */
bool
IsPreferredType(TYPCATEGORY category, Oid type)
{
  char    typcategory;
  bool    typispreferred;

  get_type_category_preferred(type, &typcategory, &typispreferred);
  if (category == typcategory || category == TYPCATEGORY_INVALID)
    return typispreferred;
  else
    return false;
}


/*
 * IsBinaryCoercible()
 *    Check if srctype is binary-coercible to targettype.
 *
 * This notion allows us to cheat and directly exchange values without
 * going through the trouble of calling a conversion function.  Note that
 * in general, this should only be an implementation shortcut.  Before 7.4,
 * this was also used as a heuristic for resolving overloaded functions and
 * operators, but that's basically a bad idea.
 *
 * As of 7.3, binary coercibility isn't hardwired into the code anymore.
 * We consider two types binary-coercible if there is an implicitly
 * invokable, no-function-needed pg_cast entry.  Also, a domain is always
 * binary-coercible to its base type, though *not* vice versa (in the other
 * direction, one must apply domain constraint checks before accepting the
 * value as legitimate).  We also need to special-case various polymorphic
 * types.
 *
 * This function replaces IsBinaryCompatible(), which was an inherently
 * symmetric test.  Since the pg_cast entries aren't necessarily symmetric,
 * the order of the operands is now significant.
 */
bool
IsBinaryCoercible(Oid srctype, Oid targettype)
{
  Oid     castoid;

  return IsBinaryCoercibleWithCast(srctype, targettype, &castoid);
}

/*
 * IsBinaryCoercibleWithCast()
 *    Check if srctype is binary-coercible to targettype.
 *
 * This variant also returns the OID of the pg_cast entry if one is involved.
 * *castoid is set to InvalidOid if no binary-coercible cast exists, or if
 * there is a hard-wired rule for it rather than a pg_cast entry.
 */
bool
IsBinaryCoercibleWithCast(Oid srctype, Oid targettype,
              Oid *castoid)
{
  HeapTuple tuple;
  Form_pg_cast castForm;
  bool    result;

  *castoid = InvalidOid;

  /* Fast path if same type */
  if (srctype == targettype)
    return true;

  /* Anything is coercible to ANY or ANYELEMENT or ANYCOMPATIBLE */
  if (targettype == ANYOID || targettype == ANYELEMENTOID ||
    targettype == ANYCOMPATIBLEOID)
    return true;

  /* If srctype is a domain, reduce to its base type */
  if (OidIsValid(srctype))
    srctype = getBaseType(srctype);

  /* Somewhat-fast path for domain -> base type case */
  if (srctype == targettype)
    return true;

  /* Also accept any array type as coercible to ANY[COMPATIBLE]ARRAY */
  if (targettype == ANYARRAYOID || targettype == ANYCOMPATIBLEARRAYOID)
    if (type_is_array(srctype))
      return true;

  /* Also accept any non-array type as coercible to ANY[COMPATIBLE]NONARRAY */
  if (targettype == ANYNONARRAYOID || targettype == ANYCOMPATIBLENONARRAYOID)
    if (!type_is_array(srctype))
      return true;

  /* Also accept any enum type as coercible to ANYENUM */
  if (targettype == ANYENUMOID)
    if (type_is_enum(srctype))
      return true;

  /* Also accept any range type as coercible to ANY[COMPATIBLE]RANGE */
  if (targettype == ANYRANGEOID || targettype == ANYCOMPATIBLERANGEOID)
    if (type_is_range(srctype))
      return true;

  /* Also, any multirange type is coercible to ANY[COMPATIBLE]MULTIRANGE */
  if (targettype == ANYMULTIRANGEOID || targettype == ANYCOMPATIBLEMULTIRANGEOID)
    if (type_is_multirange(srctype))
      return true;

  /* Also accept any composite type as coercible to RECORD */
  if (targettype == RECORDOID)
    if (ISCOMPLEX(srctype))
      return true;

  /* Also accept any composite array type as coercible to RECORD[] */
  if (targettype == RECORDARRAYOID)
    if (is_complex_array(srctype))
      return true;

  /* Else look in pg_cast */
  tuple = SearchSysCache2(CASTSOURCETARGET,
              ObjectIdGetDatum(srctype),
              ObjectIdGetDatum(targettype));
  if (!HeapTupleIsValid(tuple))
    return false;     /* no cast */
  castForm = (Form_pg_cast) GETSTRUCT(tuple);

  result = (castForm->castmethod == COERCION_METHOD_BINARY &&
        castForm->castcontext == COERCION_CODE_IMPLICIT);

  if (result)
    *castoid = castForm->oid;

  ReleaseSysCache(tuple);

  return result;
}


/*
 * find_coercion_pathway
 *    Look for a coercion pathway between two types.
 *
 * Currently, this deals only with scalar-type cases; it does not consider
 * polymorphic types nor casts between composite types.  (Perhaps fold
 * those in someday?)
 *
 * ccontext determines the set of available casts.
 *
 * The possible result codes are:
 *  COERCION_PATH_NONE: failed to find any coercion pathway
 *        *funcid is set to InvalidOid
 *  COERCION_PATH_FUNC: apply the coercion function returned in *funcid
 *  COERCION_PATH_RELABELTYPE: binary-compatible cast, no function needed
 *        *funcid is set to InvalidOid
 *  COERCION_PATH_ARRAYCOERCE: need an ArrayCoerceExpr node
 *        *funcid is set to InvalidOid
 *  COERCION_PATH_COERCEVIAIO: need a CoerceViaIO node
 *        *funcid is set to InvalidOid
 *
 * Note: COERCION_PATH_RELABELTYPE does not necessarily mean that no work is
 * needed to do the coercion; if the target is a domain then we may need to
 * apply domain constraint checking.  If you want to check for a zero-effort
 * conversion then use IsBinaryCoercible().
 */
CoercionPathType
find_coercion_pathway(Oid targetTypeId, Oid sourceTypeId,
            CoercionContext ccontext,
            Oid *funcid)
{
  CoercionPathType result = COERCION_PATH_NONE;
  HeapTuple tuple;

  *funcid = InvalidOid;

  /* Perhaps the types are domains; if so, look at their base types */
  if (OidIsValid(sourceTypeId))
    sourceTypeId = getBaseType(sourceTypeId);
  if (OidIsValid(targetTypeId))
    targetTypeId = getBaseType(targetTypeId);

  /* Domains are always coercible to and from their base type */
  if (sourceTypeId == targetTypeId)
    return COERCION_PATH_RELABELTYPE;

  /* Reject all cases of casting something else to/from "internal" */
  if (sourceTypeId == INTERNALOID || targetTypeId == INTERNALOID)
    return COERCION_PATH_NONE;

  /* Look in pg_cast */
  tuple = SearchSysCache2(CASTSOURCETARGET,
              ObjectIdGetDatum(sourceTypeId),
              ObjectIdGetDatum(targetTypeId));

  if (HeapTupleIsValid(tuple))
  {
    Form_pg_cast castForm = (Form_pg_cast) GETSTRUCT(tuple);
    CoercionContext castcontext;

    /* convert char value for castcontext to CoercionContext enum */
    switch (castForm->castcontext)
    {
      case COERCION_CODE_IMPLICIT:
        castcontext = COERCION_IMPLICIT;
        break;
      case COERCION_CODE_ASSIGNMENT:
        castcontext = COERCION_ASSIGNMENT;
        break;
      case COERCION_CODE_EXPLICIT:
        castcontext = COERCION_EXPLICIT;
        break;
      default:
        elog(ERROR, "unrecognized castcontext: %d",
           (int) castForm->castcontext);
        castcontext = 0;  /* keep compiler quiet */
        break;
    }

    /* Rely on ordering of enum for correct behavior here */
    if (ccontext >= castcontext)
    {
      switch (castForm->castmethod)
      {
        case COERCION_METHOD_FUNCTION:
          result = COERCION_PATH_FUNC;
          *funcid = castForm->castfunc;
          break;
        case COERCION_METHOD_INOUT:
          result = COERCION_PATH_COERCEVIAIO;
          break;
        case COERCION_METHOD_BINARY:
          result = COERCION_PATH_RELABELTYPE;
          break;
        default:
          elog(ERROR, "unrecognized castmethod: %d",
             (int) castForm->castmethod);
          break;
      }
    }

    ReleaseSysCache(tuple);
  }
  else
  {
    /*
     * If there's no pg_cast entry, perhaps we are dealing with a pair of
     * array types.  If so, and if their element types have a conversion
     * pathway, report that we can coerce with an ArrayCoerceExpr.
     *
     * Hack: disallow coercions to oidvector and int2vector, which
     * otherwise tend to capture coercions that should go to "real" array
     * types.  We want those types to be considered "real" arrays for many
     * purposes, but not this one.  (Also, ArrayCoerceExpr isn't
     * guaranteed to produce an output that meets the restrictions of
     * these datatypes, such as being 1-dimensional.)
     */
    if (targetTypeId != OIDVECTOROID && targetTypeId != INT2VECTOROID)
    {
      Oid     targetElem;
      Oid     sourceElem;

      if ((targetElem = get_element_type(targetTypeId)) != InvalidOid &&
        (sourceElem = get_element_type(sourceTypeId)) != InvalidOid)
      {
        CoercionPathType elempathtype;
        Oid     elemfuncid;

        elempathtype = find_coercion_pathway(targetElem,
                           sourceElem,
                           ccontext,
                           &elemfuncid);
        if (elempathtype != COERCION_PATH_NONE)
        {
          result = COERCION_PATH_ARRAYCOERCE;
        }
      }
    }

    /*
     * If we still haven't found a possibility, consider automatic casting
     * using I/O functions.  We allow assignment casts to string types and
     * explicit casts from string types to be handled this way. (The
     * CoerceViaIO mechanism is a lot more general than that, but this is
     * all we want to allow in the absence of a pg_cast entry.) It would
     * probably be better to insist on explicit casts in both directions,
     * but this is a compromise to preserve something of the pre-8.3
     * behavior that many types had implicit (yipes!) casts to text.
     */
    if (result == COERCION_PATH_NONE)
    {
      if (ccontext >= COERCION_ASSIGNMENT &&
        TypeCategory(targetTypeId) == TYPCATEGORY_STRING)
        result = COERCION_PATH_COERCEVIAIO;
      else if (ccontext >= COERCION_EXPLICIT &&
           TypeCategory(sourceTypeId) == TYPCATEGORY_STRING)
        result = COERCION_PATH_COERCEVIAIO;
    }
  }

  /*
   * When parsing PL/pgSQL assignments, allow an I/O cast to be used
   * whenever no normal coercion is available.
   */
  if (result == COERCION_PATH_NONE &&
    ccontext == COERCION_PLPGSQL)
    result = COERCION_PATH_COERCEVIAIO;

  return result;
}


/*
 * find_typmod_coercion_function -- does the given type need length coercion?
 *
 * If the target type possesses a pg_cast function from itself to itself,
 * it must need length coercion.
 *
 * "bpchar" (ie, char(N)) and "numeric" are examples of such types.
 *
 * If the given type is a varlena array type, we do not look for a coercion
 * function associated directly with the array type, but instead look for
 * one associated with the element type.  An ArrayCoerceExpr node must be
 * used to apply such a function.  (Note: currently, it's pointless to
 * return the funcid in this case, because it'll just get looked up again
 * in the recursive construction of the ArrayCoerceExpr's elemexpr.)
 *
 * We use the same result enum as find_coercion_pathway, but the only possible
 * result codes are:
 *  COERCION_PATH_NONE: no length coercion needed
 *  COERCION_PATH_FUNC: apply the function returned in *funcid
 *  COERCION_PATH_ARRAYCOERCE: apply the function using ArrayCoerceExpr
 */
CoercionPathType
find_typmod_coercion_function(Oid typeId,
                Oid *funcid)
{
  CoercionPathType result;
  Type    targetType;
  Form_pg_type typeForm;
  HeapTuple tuple;

  *funcid = InvalidOid;
  result = COERCION_PATH_FUNC;

  targetType = typeidType(typeId);
  typeForm = (Form_pg_type) GETSTRUCT(targetType);

  /* Check for a "true" array type */
  if (IsTrueArrayType(typeForm))
  {
    /* Yes, switch our attention to the element type */
    typeId = typeForm->typelem;
    result = COERCION_PATH_ARRAYCOERCE;
  }
  ReleaseSysCache(targetType);

  /* Look in pg_cast */
  tuple = SearchSysCache2(CASTSOURCETARGET,
              ObjectIdGetDatum(typeId),
              ObjectIdGetDatum(typeId));

  if (HeapTupleIsValid(tuple))
  {
    Form_pg_cast castForm = (Form_pg_cast) GETSTRUCT(tuple);

    *funcid = castForm->castfunc;
    ReleaseSysCache(tuple);
  }

  if (!OidIsValid(*funcid))
    result = COERCION_PATH_NONE;

  return result;
}

/*
 * is_complex_array
 *    Is this type an array of composite?
 *
 * Note: this will not return true for record[]; check for RECORDARRAYOID
 * separately if needed.
 */
static bool
is_complex_array(Oid typid)
{
  Oid     elemtype = get_element_type(typid);

  return (OidIsValid(elemtype) && ISCOMPLEX(elemtype));
}


/*
 * Check whether reltypeId is the row type of a typed table of type
 * reloftypeId, or is a domain over such a row type.  (This is conceptually
 * similar to the subtype relationship checked by typeInheritsFrom().)
 */
static bool
typeIsOfTypedTable(Oid reltypeId, Oid reloftypeId)
{
  Oid     relid = typeOrDomainTypeRelid(reltypeId);
  bool    result = false;

  if (relid)
  {
    HeapTuple tp;
    Form_pg_class reltup;

    tp = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(tp))
      elog(ERROR, "cache lookup failed for relation %u", relid);

    reltup = (Form_pg_class) GETSTRUCT(tp);
    if (reltup->reloftype == reloftypeId)
      result = true;

    ReleaseSysCache(tp);
  }

  return result;
}

Coverage Report

Created: 2026-11-12 07:20