Improve the error message for an inappropriate column definition list.

The existing message about "a column definition list is only allowed for
functions returning "record"" could be given in some cases where it was
fairly confusing; in particular, a function with multiple OUT parameters
*does* return record according to pg_proc.  Break it down into a couple
more cases to deliver a more on-point complaint.  Per complaint from
Bruce Momjian.

Discussion: https://postgr.es/m/798909.1600562993@sss.pgh.pa.us

diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index b875a506463f813def8fc1227fb80731b675bb3f..a56bd86181a70e5136244e9a76d3f2499bcd40d8 100644 (file)
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -1737,16 +1737,46 @@ addRangeTableEntryForFunction(ParseState *pstate,
 
                /*
                 * A coldeflist is required if the function returns RECORD and hasn't
-                * got a predetermined record type, and is prohibited otherwise.
+                * got a predetermined record type, and is prohibited otherwise.  This
+                * can be a bit confusing, so we expend some effort on delivering a
+                * relevant error message.
                 */
                if (coldeflist != NIL)
                {
-                       if (functypclass != TYPEFUNC_RECORD)
-                               ereport(ERROR,
-                                               (errcode(ERRCODE_SYNTAX_ERROR),
-                                                errmsg("a column definition list is only allowed for functions returning \"record\""),
-                                                parser_errposition(pstate,
-                                                                                       exprLocation((Node *) coldeflist))));
+                       switch (functypclass)
+                       {
+                               case TYPEFUNC_RECORD:
+                                       /* ok */
+                                       break;
+                               case TYPEFUNC_COMPOSITE:
+                               case TYPEFUNC_COMPOSITE_DOMAIN:
+
+                                       /*
+                                        * If the function's raw result type is RECORD, we must
+                                        * have resolved it using its OUT parameters.  Otherwise,
+                                        * it must have a named composite type.
+                                        */
+                                       if (exprType(funcexpr) == RECORDOID)
+                                               ereport(ERROR,
+                                                               (errcode(ERRCODE_SYNTAX_ERROR),
+                                                                errmsg("a column definition list is redundant for a function with OUT parameters"),
+                                                                parser_errposition(pstate,
+                                                                                                       exprLocation((Node *) coldeflist))));
+                                       else
+                                               ereport(ERROR,
+                                                               (errcode(ERRCODE_SYNTAX_ERROR),
+                                                                errmsg("a column definition list is redundant for a function returning a named composite type"),
+                                                                parser_errposition(pstate,
+                                                                                                       exprLocation((Node *) coldeflist))));
+                                       break;
+                               default:
+                                       ereport(ERROR,
+                                                       (errcode(ERRCODE_SYNTAX_ERROR),
+                                                        errmsg("a column definition list is only allowed for functions returning \"record\""),
+                                                        parser_errposition(pstate,
+                                                                                               exprLocation((Node *) coldeflist))));
+                                       break;
+                       }
                }
                else
                {

diff --git a/src/test/regress/expected/rangefuncs.out b/src/test/regress/expected/rangefuncs.out
index 7eced2845203785a6648546a87dc531b1581d1ea..e618aec2ebca82c8b399718c64ff79c55e77b842 100644 (file)
--- a/src/test/regress/expected/rangefuncs.out
+++ b/src/test/regress/expected/rangefuncs.out
@@ -2109,6 +2109,19 @@ select * from testrngfunc();
  7.136178 | 7.14
 (1 row)
 
+-- Check a couple of error cases while we're here
+select * from testrngfunc() as t(f1 int8,f2 int8);  -- fail, composite result
+ERROR:  a column definition list is redundant for a function returning a named composite type
+LINE 1: select * from testrngfunc() as t(f1 int8,f2 int8);
+                                         ^
+select * from pg_get_keywords() as t(f1 int8,f2 int8);  -- fail, OUT params
+ERROR:  a column definition list is redundant for a function with OUT parameters
+LINE 1: select * from pg_get_keywords() as t(f1 int8,f2 int8);
+                                             ^
+select * from sin(3) as t(f1 int8,f2 int8);  -- fail, scalar result type
+ERROR:  a column definition list is only allowed for functions returning "record"
+LINE 1: select * from sin(3) as t(f1 int8,f2 int8);
+                                  ^
 drop type rngfunc_type cascade;
 NOTICE:  drop cascades to function testrngfunc()
 --

diff --git a/src/test/regress/sql/rangefuncs.sql b/src/test/regress/sql/rangefuncs.sql
index ae3119a959eb87321e8484f1915cef1016162dce..5f41cb2d8d0b10195da2d1c6966df76b748f495f 100644 (file)
--- a/src/test/regress/sql/rangefuncs.sql
+++ b/src/test/regress/sql/rangefuncs.sql
@@ -629,6 +629,11 @@ explain (verbose, costs off)
 select * from testrngfunc();
 select * from testrngfunc();
 
+-- Check a couple of error cases while we're here
+select * from testrngfunc() as t(f1 int8,f2 int8);  -- fail, composite result
+select * from pg_get_keywords() as t(f1 int8,f2 int8);  -- fail, OUT params
+select * from sin(3) as t(f1 int8,f2 int8);  -- fail, scalar result type
+
 drop type rngfunc_type cascade;
 
 --