get_expr_result_type has to be prepared to pull type information

from a RECORD Const node, because that's what it may be faced with
after constant-folding of a function returning RECORD.  Per example
from Michael Fuhr.

diff --git a/src/backend/utils/fmgr/funcapi.c b/src/backend/utils/fmgr/funcapi.c
index 3310c9b026afdf8b8250e13d9a8e3d30be1f57f0..3ecb59eec8eada76e6398edf15a64f8b67588a95 100644 (file)
--- a/src/backend/utils/fmgr/funcapi.c
+++ b/src/backend/utils/fmgr/funcapi.c
@@ -7,7 +7,7 @@
  * Copyright (c) 2002-2005, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/utils/fmgr/funcapi.c,v 1.21 2005/04/25 20:59:44 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/utils/fmgr/funcapi.c,v 1.22 2005/05/28 05:10:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -235,6 +235,36 @@ get_expr_result_type(Node *expr,
                                          NULL,
                                          resultTypeId,
                                          resultTupleDesc);
+   else if (expr && IsA(expr, Const) &&
+            ((Const *) expr)->consttype == RECORDOID &&
+            !((Const *) expr)->constisnull)
+   {
+       /*
+        * Pull embedded type info from a RECORD constant.  We have to be
+        * prepared to handle this case in the wake of constant-folding of
+        * record-returning functions.
+        */
+       HeapTupleHeader td;
+       int32   typmod;
+
+       td = DatumGetHeapTupleHeader(((Const *) expr)->constvalue);
+       Assert(HeapTupleHeaderGetTypeId(td) == RECORDOID);
+       typmod = HeapTupleHeaderGetTypMod(td);
+       if (resultTypeId)
+           *resultTypeId = RECORDOID;
+       if (typmod >= 0)
+       {
+           if (resultTupleDesc)
+               *resultTupleDesc = lookup_rowtype_tupdesc(RECORDOID, typmod);
+           result = TYPEFUNC_COMPOSITE;
+       }
+       else
+       {
+           if (resultTupleDesc)
+               *resultTupleDesc = NULL;
+           result = TYPEFUNC_RECORD;
+       }
+   }
    else
    {
        /* handle as a generic expression; no chance to resolve RECORD */