Need to special-case RECORD as well as UNKNOWN in plpgsql's casting logic.

This is because can_coerce_type thinks that RECORD can be cast to any
composite type, but coerce_record_to_complex only works for inputs that are
RowExprs or whole-row Vars, so we get a hard failure on a CaseTestExpr.

Perhaps these corner cases ought to be fixed so that coerce_to_target_type
actually returns NULL as per its specification, rather than failing ...
but for the moment an extra check here is the path of least resistance.

diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 4030b647fb029ab30cb560753f387750c921905d..315d28b8fae8e6cac9efb7b9af94fb82e3b19b89 100644 (file)
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -5829,17 +5829,18 @@ get_cast_expression(PLpgSQL_execstate *estate,
         *
         * If source type is UNKNOWN, coerce_to_target_type will fail (it only
         * expects to see that for Const input nodes), so don't call it; we'll
-        * apply CoerceViaIO instead.
+        * apply CoerceViaIO instead.  Likewise, it doesn't currently work for
+        * coercing RECORD to some other type, so skip for that too.
         */
-       if (srctype != UNKNOWNOID)
+       if (srctype == UNKNOWNOID || srctype == RECORDOID)
+               cast_expr = NULL;
+       else
                cast_expr = coerce_to_target_type(NULL,
                                                                                  (Node *) placeholder, srctype,
                                                                                  dsttype, dsttypmod,
                                                                                  COERCION_ASSIGNMENT,
                                                                                  COERCE_IMPLICIT_CAST,
                                                                                  -1);
-       else
-               cast_expr = NULL;
 
        /*
         * If there's no cast path according to the parser, fall back to using an