1 files changed, 33 insertions, 25 deletions

diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index be9d23bc323..e0839616e19 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -1225,6 +1225,7 @@ ExecInitExprRec(Expr *node, PlanState *parent, ExprState *state,
 			{
 				ArrayCoerceExpr *acoerce = (ArrayCoerceExpr *) node;
 				Oid			resultelemtype;
+				ExprState  *elemstate;
 
 				/* evaluate argument into step's result area */
 				ExecInitExprRec(acoerce->arg, parent, state, resv, resnull);
@@ -1234,42 +1235,49 @@ ExecInitExprRec(Expr *node, PlanState *parent, ExprState *state,
 					ereport(ERROR,
 							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 							 errmsg("target type is not an array")));
-				/* Arrays over domains aren't supported yet */
-				Assert(getBaseType(resultelemtype) == resultelemtype);
 
-				scratch.opcode = EEOP_ARRAYCOERCE;
-				scratch.d.arraycoerce.coerceexpr = acoerce;
-				scratch.d.arraycoerce.resultelemtype = resultelemtype;
+				/*
+				 * Construct a sub-expression for the per-element expression;
+				 * but don't ready it until after we check it for triviality.
+				 * We assume it hasn't any Var references, but does have a
+				 * CaseTestExpr representing the source array element values.
+				 */
+				elemstate = makeNode(ExprState);
+				elemstate->expr = acoerce->elemexpr;
+				elemstate->innermost_caseval = (Datum *) palloc(sizeof(Datum));
+				elemstate->innermost_casenull = (bool *) palloc(sizeof(bool));
 
-				if (OidIsValid(acoerce->elemfuncid))
-				{
-					AclResult	aclresult;
+				ExecInitExprRec(acoerce->elemexpr, parent, elemstate,
+								&elemstate->resvalue, &elemstate->resnull);
 
-					/* Check permission to call function */
-					aclresult = pg_proc_aclcheck(acoerce->elemfuncid,
-												 GetUserId(),
-												 ACL_EXECUTE);
-					if (aclresult != ACLCHECK_OK)
-						aclcheck_error(aclresult, ACL_KIND_PROC,
-									   get_func_name(acoerce->elemfuncid));
-					InvokeFunctionExecuteHook(acoerce->elemfuncid);
+				if (elemstate->steps_len == 1 &&
+					elemstate->steps[0].opcode == EEOP_CASE_TESTVAL)
+				{
+					/* Trivial, so we need no per-element work at runtime */
+					elemstate = NULL;
+				}
+				else
+				{
+					/* Not trivial, so append a DONE step */
+					scratch.opcode = EEOP_DONE;
+					ExprEvalPushStep(elemstate, &scratch);
+					/* and ready the subexpression */
+					ExecReadyExpr(elemstate);
+				}
 
-					/* Set up the primary fmgr lookup information */
-					scratch.d.arraycoerce.elemfunc =
-						(FmgrInfo *) palloc0(sizeof(FmgrInfo));
-					fmgr_info(acoerce->elemfuncid,
-							  scratch.d.arraycoerce.elemfunc);
-					fmgr_info_set_expr((Node *) acoerce,
-									   scratch.d.arraycoerce.elemfunc);
+				scratch.opcode = EEOP_ARRAYCOERCE;
+				scratch.d.arraycoerce.elemexprstate = elemstate;
+				scratch.d.arraycoerce.resultelemtype = resultelemtype;
 
+				if (elemstate)
+				{
 					/* Set up workspace for array_map */
 					scratch.d.arraycoerce.amstate =
 						(ArrayMapState *) palloc0(sizeof(ArrayMapState));
 				}
 				else
 				{
-					/* Don't need workspace if there's no conversion func */
-					scratch.d.arraycoerce.elemfunc = NULL;
+					/* Don't need workspace if there's no subexpression */
 					scratch.d.arraycoerce.amstate = NULL;
 				}