diff --git a/src/backend/executor/nodeFunctionscan.c b/src/backend/executor/nodeFunctionscan.c
index 434379a5aa..cc257317e5 100644
--- a/src/backend/executor/nodeFunctionscan.c
+++ b/src/backend/executor/nodeFunctionscan.c
@@ -344,8 +344,6 @@ ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags)
 		Node	   *funcexpr = rtfunc->funcexpr;
 		int			colcount = rtfunc->funccolcount;
 		FunctionScanPerFuncState *fs = &scanstate->funcstates[i];
-		TypeFuncClass functypclass;
-		Oid			funcrettype;
 		TupleDesc	tupdesc;
 
 		fs->setexpr =
@@ -362,39 +360,18 @@ ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags)
 		fs->rowcount = -1;
 
 		/*
-		 * Now determine if the function returns a simple or composite type,
-		 * and build an appropriate tupdesc.  Note that in the composite case,
-		 * the function may now return more columns than it did when the plan
-		 * was made; we have to ignore any columns beyond "colcount".
+		 * Now build a tupdesc showing the result type we expect from the
+		 * function.  If we have a coldeflist then that takes priority (note
+		 * the parser enforces that there is one if the function's nominal
+		 * output type is RECORD).  Otherwise use get_expr_result_type.
+		 *
+		 * Note that if the function returns a named composite type, that may
+		 * now contain more or different columns than it did when the plan was
+		 * made.  For both that and the RECORD case, we need to check tuple
+		 * compatibility.  ExecMakeTableFunctionResult handles some of this,
+		 * and CheckVarSlotCompatibility provides a backstop.
 		 */
-		functypclass = get_expr_result_type(funcexpr,
-											&funcrettype,
-											&tupdesc);
-
-		if (functypclass == TYPEFUNC_COMPOSITE ||
-			functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
-		{
-			/* Composite data type, e.g. a table's row type */
-			Assert(tupdesc);
-			Assert(tupdesc->natts >= colcount);
-			/* Must copy it out of typcache for safety */
-			tupdesc = CreateTupleDescCopy(tupdesc);
-		}
-		else if (functypclass == TYPEFUNC_SCALAR)
-		{
-			/* Base data type, i.e. scalar */
-			tupdesc = CreateTemplateTupleDesc(1);
-			TupleDescInitEntry(tupdesc,
-							   (AttrNumber) 1,
-							   NULL,	/* don't care about the name here */
-							   funcrettype,
-							   -1,
-							   0);
-			TupleDescInitEntryCollation(tupdesc,
-										(AttrNumber) 1,
-										exprCollation(funcexpr));
-		}
-		else if (functypclass == TYPEFUNC_RECORD)
+		if (rtfunc->funccolnames != NIL)
 		{
 			tupdesc = BuildDescFromLists(rtfunc->funccolnames,
 										 rtfunc->funccoltypes,
@@ -410,8 +387,40 @@ ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags)
 		}
 		else
 		{
-			/* crummy error message, but parser should have caught this */
-			elog(ERROR, "function in FROM has unsupported return type");
+			TypeFuncClass functypclass;
+			Oid			funcrettype;
+
+			functypclass = get_expr_result_type(funcexpr,
+												&funcrettype,
+												&tupdesc);
+
+			if (functypclass == TYPEFUNC_COMPOSITE ||
+				functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
+			{
+				/* Composite data type, e.g. a table's row type */
+				Assert(tupdesc);
+				/* Must copy it out of typcache for safety */
+				tupdesc = CreateTupleDescCopy(tupdesc);
+			}
+			else if (functypclass == TYPEFUNC_SCALAR)
+			{
+				/* Base data type, i.e. scalar */
+				tupdesc = CreateTemplateTupleDesc(1);
+				TupleDescInitEntry(tupdesc,
+								   (AttrNumber) 1,
+								   NULL,	/* don't care about the name here */
+								   funcrettype,
+								   -1,
+								   0);
+				TupleDescInitEntryCollation(tupdesc,
+											(AttrNumber) 1,
+											exprCollation(funcexpr));
+			}
+			else
+			{
+				/* crummy error message, but parser should have caught this */
+				elog(ERROR, "function in FROM has unsupported return type");
+			}
 		}
 
 		fs->tupdesc = tupdesc;
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index e1cedd9448..3ef684a75d 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -5134,16 +5134,20 @@ inline_set_returning_function(PlannerInfo *root, RangeTblEntry *rte)
 	}
 
 	/*
-	 * Also resolve the actual function result tupdesc, if composite.  If the
-	 * function is just declared to return RECORD, dig the info out of the AS
-	 * clause.
+	 * Also resolve the actual function result tupdesc, if composite.  If we
+	 * have a coldeflist, believe that; otherwise use get_expr_result_type.
+	 * (This logic should match ExecInitFunctionScan.)
 	 */
-	functypclass = get_expr_result_type((Node *) fexpr, NULL, &rettupdesc);
-	if (functypclass == TYPEFUNC_RECORD)
+	if (rtfunc->funccolnames != NIL)
+	{
+		functypclass = TYPEFUNC_RECORD;
 		rettupdesc = BuildDescFromLists(rtfunc->funccolnames,
 										rtfunc->funccoltypes,
 										rtfunc->funccoltypmods,
 										rtfunc->funccolcollations);
+	}
+	else
+		functypclass = get_expr_result_type((Node *) fexpr, NULL, &rettupdesc);
 
 	/*
 	 * The single command must be a plain SELECT.
diff --git a/src/test/regress/expected/rangefuncs.out b/src/test/regress/expected/rangefuncs.out
index e2e62db6a2..d8d1f944f3 100644
--- a/src/test/regress/expected/rangefuncs.out
+++ b/src/test/regress/expected/rangefuncs.out
@@ -2485,3 +2485,16 @@ select * from
  [{"id": "1"}] | 1
 (1 row)
 
+-- check detection of mismatching record types with a const-folded expression
+with a(b) as (values (row(1,2,3)))
+select * from a, coalesce(b) as c(d int, e int);  -- fail
+ERROR:  function return row and query-specified return row do not match
+DETAIL:  Returned row contains 3 attributes, but query expects 2.
+with a(b) as (values (row(1,2,3)))
+select * from a, coalesce(b) as c(d int, e int, f int, g int);  -- fail
+ERROR:  function return row and query-specified return row do not match
+DETAIL:  Returned row contains 3 attributes, but query expects 4.
+with a(b) as (values (row(1,2,3)))
+select * from a, coalesce(b) as c(d int, e int, f float);  -- fail
+ERROR:  function return row and query-specified return row do not match
+DETAIL:  Returned type integer at ordinal position 3, but query expects double precision.
diff --git a/src/test/regress/sql/rangefuncs.sql b/src/test/regress/sql/rangefuncs.sql
index 63351e1412..06d598c5e9 100644
--- a/src/test/regress/sql/rangefuncs.sql
+++ b/src/test/regress/sql/rangefuncs.sql
@@ -815,3 +815,12 @@ select * from
    from unnest(array['{"lectures": [{"id": "1"}]}'::jsonb])
         as unnested_modules(module)) as ss,
   jsonb_to_recordset(ss.lecture) as j (id text);
+
+-- check detection of mismatching record types with a const-folded expression
+
+with a(b) as (values (row(1,2,3)))
+select * from a, coalesce(b) as c(d int, e int);  -- fail
+with a(b) as (values (row(1,2,3)))
+select * from a, coalesce(b) as c(d int, e int, f int, g int);  -- fail
+with a(b) as (values (row(1,2,3)))
+select * from a, coalesce(b) as c(d int, e int, f float);  -- fail