Allow the syntax CREATE TYPE foo, with no parameters, to permit explicit

creation of a shell type.  This allows a less hacky way of dealing with
the mutual dependency between a datatype and its I/O functions: make a
shell type, then make the functions, then define the datatype fully.
We should fix pg_dump to handle things this way, but this commit just deals
with the backend.

Martijn van Oosterhout, with some corrections by Tom Lane.

2 files changed, 45 insertions, 4 deletions

diff --git a/src/test/regress/expected/create_type.out b/src/test/regress/expected/create_type.out
index 4e2d44d5c41..3e2edeb1e0b 100644
--- a/src/test/regress/expected/create_type.out
+++ b/src/test/regress/expected/create_type.out
@@ -1,6 +1,11 @@
 --
 -- CREATE_TYPE
 --
+--
+-- Note: widget_in/out were created in create_function_1, without any
+-- prior shell-type creation.  These commands therefore complete a test
+-- of the "old style" approach of making the functions first.
+--
 CREATE TYPE widget (
    internallength = 24, 
    input = widget_in,
@@ -13,14 +18,27 @@ CREATE TYPE city_budget (
    output = int44out, 
    element = int4
 );
+-- Test creation and destruction of shell types
+CREATE TYPE shell;
+CREATE TYPE shell;   -- fail, type already present
+ERROR:  type "shell" already exists
+DROP TYPE shell;
+DROP TYPE shell;     -- fail, type not exist
+ERROR:  type "shell" does not exist
+--
 -- Test type-related default values (broken in releases before PG 7.2)
+--
+-- This part of the test also exercises the "new style" approach of making
+-- a shell type and then filling it in.
+--
+CREATE TYPE int42;
+CREATE TYPE text_w_default;
 -- Make dummy I/O routines using the existing internal support for int4, text
 CREATE FUNCTION int42_in(cstring)
    RETURNS int42
    AS 'int4in'
    LANGUAGE internal STRICT;
-NOTICE:  type "int42" is not yet defined
-DETAIL:  Creating a shell type definition.
+NOTICE:  return type int42 is only a shell
 CREATE FUNCTION int42_out(int42)
    RETURNS cstring
    AS 'int4out'
@@ -30,8 +48,7 @@ CREATE FUNCTION text_w_default_in(cstring)
    RETURNS text_w_default
    AS 'textin'
    LANGUAGE internal STRICT;
-NOTICE:  type "text_w_default" is not yet defined
-DETAIL:  Creating a shell type definition.
+NOTICE:  return type text_w_default is only a shell
 CREATE FUNCTION text_w_default_out(text_w_default)
    RETURNS cstring
    AS 'textout'
@@ -76,6 +93,9 @@ COMMENT ON TYPE bad IS 'bad comment';
 ERROR:  type "bad" does not exist
 COMMENT ON TYPE default_test_row IS 'good comment';
 COMMENT ON TYPE default_test_row IS NULL;
+-- Check shell type create for existing types
+CREATE TYPE text_w_default;		-- should fail
+ERROR:  type "text_w_default" already exists
 DROP TYPE default_test_row CASCADE;
 NOTICE:  drop cascades to function get_default_test()
 DROP TABLE default_test;
diff --git a/src/test/regress/sql/create_type.sql b/src/test/regress/sql/create_type.sql
index 66d78c9216b..097d51fc925 100644
--- a/src/test/regress/sql/create_type.sql
+++ b/src/test/regress/sql/create_type.sql
@@ -2,6 +2,11 @@
 -- CREATE_TYPE
 --
 
+--
+-- Note: widget_in/out were created in create_function_1, without any
+-- prior shell-type creation.  These commands therefore complete a test
+-- of the "old style" approach of making the functions first.
+--
 CREATE TYPE widget (
    internallength = 24, 
    input = widget_in,
@@ -16,7 +21,20 @@ CREATE TYPE city_budget (
    element = int4
 );
 
+-- Test creation and destruction of shell types
+CREATE TYPE shell;
+CREATE TYPE shell;   -- fail, type already present
+DROP TYPE shell;
+DROP TYPE shell;     -- fail, type not exist
+
+--
 -- Test type-related default values (broken in releases before PG 7.2)
+--
+-- This part of the test also exercises the "new style" approach of making
+-- a shell type and then filling it in.
+--
+CREATE TYPE int42;
+CREATE TYPE text_w_default;
 
 -- Make dummy I/O routines using the existing internal support for int4, text
 CREATE FUNCTION int42_in(cstring)
@@ -74,6 +92,9 @@ COMMENT ON TYPE bad IS 'bad comment';
 COMMENT ON TYPE default_test_row IS 'good comment';
 COMMENT ON TYPE default_test_row IS NULL;
 
+-- Check shell type create for existing types
+CREATE TYPE text_w_default;		-- should fail
+
 DROP TYPE default_test_row CASCADE;
 
 DROP TABLE default_test;