Remove the "opaque" pseudo-type and associated compatibility hacks.

A long time ago, it was necessary to declare datatype I/O functions,
triggers, and language handler support functions in a very type-unsafe
way involving a single pseudo-type "opaque".  We got rid of those
conventions in 7.3, but there was still support in various places to
automatically convert such functions to the modern declaration style,
to be able to transparently re-load dumps from pre-7.3 servers.
It seems unnecessary to continue to support that anymore, so take out
the hacks; whereupon the "opaque" pseudo-type itself is no longer
needed and can be dropped.

This is part of a group of patches removing various server-side kluges
for transparently upgrading pre-8.0 dump files.  Since we've had few
complaints about dropping pg_dump's support for dumping from pre-8.0
servers (commit 64f3524e), it seems okay to now remove these kluges.

Discussion: https://postgr.es/m/4110.1583255415@sss.pgh.pa.us

doc/src/sgml/datatype.sgml

@@ -4827,10 +4827,6 @@ SELECT * FROM pg_attribute
     <primary>unknown</primary>
    </indexterm>
 
-   <indexterm zone="datatype-pseudo">
-    <primary>opaque</primary>
-   </indexterm>
-
    <para>
     The <productname>PostgreSQL</productname> type system contains a
     number of special-purpose entries that are collectively called
@@ -4953,12 +4949,6 @@ SELECT * FROM pg_attribute
         <entry>Identifies a not-yet-resolved type, e.g. of an undecorated
          string literal.</entry>
        </row>
-
-       <row>
-        <entry><type>opaque</type></entry>
-        <entry>An obsolete type name that formerly served many of the above
-         purposes.</entry>
-       </row>
       </tbody>
      </tgroup>
     </table>

doc/src/sgml/ref/create_language.sgml

@@ -211,16 +211,6 @@ CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="pa
    database, which will cause it to be available automatically in
    all subsequently-created databases.
   </para>
-
-  <para>
-   In <productname>PostgreSQL</productname> versions before 7.3, it was
-   necessary to declare handler functions as returning the placeholder
-   type <type>opaque</type>, rather than <type>language_handler</type>.
-   To support loading
-   of old dump files, <command>CREATE LANGUAGE</command> will accept a function
-   declared as returning <type>opaque</type>, but it will issue a notice and
-   change the function's declared return type to <type>language_handler</type>.
-  </para>
  </refsect1>
 
  <refsect1 id="sql-createlanguage-examples">

doc/src/sgml/ref/create_trigger.sgml

@@ -543,15 +543,6 @@ UPDATE OF <replaceable>column_name1</replaceable> [, <replaceable>column_name2</
    row-level triggers with transition relations cannot be defined on
    partitions or inheritance child tables.
   </para>
-
-  <para>
-   In <productname>PostgreSQL</productname> versions before 7.3, it was
-   necessary to declare trigger functions as returning the placeholder
-   type <type>opaque</type>, rather than <type>trigger</type>.  To support loading
-   of old dump files, <command>CREATE TRIGGER</command> will accept a function
-   declared as returning <type>opaque</type>, but it will issue a notice and
-   change the function's declared return type to <type>trigger</type>.
-  </para>
  </refsect1>
 
  <refsect1 id="sql-createtrigger-examples">

doc/src/sgml/ref/create_type.sgml

@@ -823,18 +823,6 @@ CREATE TYPE <replaceable class="parameter">name</replaceable>
    function is written in C.
   </para>
 
-  <para>
-   In <productname>PostgreSQL</productname> versions before 7.3, it
-   was customary to avoid creating a shell type at all, by replacing the
-   functions' forward references to the type name with the placeholder
-   pseudo-type <type>opaque</type>.  The <type>cstring</type> arguments and
-   results also had to be declared as <type>opaque</type> before 7.3.  To
-   support loading of old dump files, <command>CREATE TYPE</command> will
-   accept I/O functions declared using <type>opaque</type>, but it will issue
-   a notice and change the function declarations to use the correct
-   types.
-  </para>
-
  </refsect1>
 
  <refsect1>

src/backend/commands/functioncmds.c

@@ -1399,93 +1399,6 @@ AlterFunction(ParseState *pstate, AlterFunctionStmt *stmt)
 	return address;
 }
 
-/*
- * SetFunctionReturnType - change declared return type of a function
- *
- * This is presently only used for adjusting legacy functions that return
- * OPAQUE to return whatever we find their correct definition should be.
- * The caller should emit a suitable warning explaining what we did.
- */
-void
-SetFunctionReturnType(Oid funcOid, Oid newRetType)
-{
-	Relation	pg_proc_rel;
-	HeapTuple	tup;
-	Form_pg_proc procForm;
-	ObjectAddress func_address;
-	ObjectAddress type_address;
-
-	pg_proc_rel = table_open(ProcedureRelationId, RowExclusiveLock);
-
-	tup = SearchSysCacheCopy1(PROCOID, ObjectIdGetDatum(funcOid));
-	if (!HeapTupleIsValid(tup)) /* should not happen */
-		elog(ERROR, "cache lookup failed for function %u", funcOid);
-	procForm = (Form_pg_proc) GETSTRUCT(tup);
-
-	if (procForm->prorettype != OPAQUEOID)	/* caller messed up */
-		elog(ERROR, "function %u doesn't return OPAQUE", funcOid);
-
-	/* okay to overwrite copied tuple */
-	procForm->prorettype = newRetType;
-
-	/* update the catalog and its indexes */
-	CatalogTupleUpdate(pg_proc_rel, &tup->t_self, tup);
-
-	table_close(pg_proc_rel, RowExclusiveLock);
-
-	/*
-	 * Also update the dependency to the new type. Opaque is a pinned type, so
-	 * there is no old dependency record for it that we would need to remove.
-	 */
-	ObjectAddressSet(type_address, TypeRelationId, newRetType);
-	ObjectAddressSet(func_address, ProcedureRelationId, funcOid);
-	recordDependencyOn(&func_address, &type_address, DEPENDENCY_NORMAL);
-}
-
-
-/*
- * SetFunctionArgType - change declared argument type of a function
- *
- * As above, but change an argument's type.
- */
-void
-SetFunctionArgType(Oid funcOid, int argIndex, Oid newArgType)
-{
-	Relation	pg_proc_rel;
-	HeapTuple	tup;
-	Form_pg_proc procForm;
-	ObjectAddress func_address;
-	ObjectAddress type_address;
-
-	pg_proc_rel = table_open(ProcedureRelationId, RowExclusiveLock);
-
-	tup = SearchSysCacheCopy1(PROCOID, ObjectIdGetDatum(funcOid));
-	if (!HeapTupleIsValid(tup)) /* should not happen */
-		elog(ERROR, "cache lookup failed for function %u", funcOid);
-	procForm = (Form_pg_proc) GETSTRUCT(tup);
-
-	if (argIndex < 0 || argIndex >= procForm->pronargs ||
-		procForm->proargtypes.values[argIndex] != OPAQUEOID)
-		elog(ERROR, "function %u doesn't take OPAQUE", funcOid);
-
-	/* okay to overwrite copied tuple */
-	procForm->proargtypes.values[argIndex] = newArgType;
-
-	/* update the catalog and its indexes */
-	CatalogTupleUpdate(pg_proc_rel, &tup->t_self, tup);
-
-	table_close(pg_proc_rel, RowExclusiveLock);
-
-	/*
-	 * Also update the dependency to the new type. Opaque is a pinned type, so
-	 * there is no old dependency record for it that we would need to remove.
-	 */
-	ObjectAddressSet(type_address, TypeRelationId, newArgType);
-	ObjectAddressSet(func_address, ProcedureRelationId, funcOid);
-	recordDependencyOn(&func_address, &type_address, DEPENDENCY_NORMAL);
-}
-
-
 
 /*
  * CREATE CAST

src/backend/commands/proclang.c

@@ -74,27 +74,10 @@ CreateProceduralLanguage(CreatePLangStmt *stmt)
 	handlerOid = LookupFuncName(stmt->plhandler, 0, NULL, false);
 	funcrettype = get_func_rettype(handlerOid);
 	if (funcrettype != LANGUAGE_HANDLEROID)
-	{
-		/*
-		 * We allow OPAQUE just so we can load old dump files.  When we see a
-		 * handler function declared OPAQUE, change it to LANGUAGE_HANDLER.
-		 * (This is probably obsolete and removable?)
-		 */
-		if (funcrettype == OPAQUEOID)
-		{
-			ereport(WARNING,
-					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("changing return type of function %s from %s to %s",
-							NameListToString(stmt->plhandler),
-							"opaque", "language_handler")));
-			SetFunctionReturnType(handlerOid, LANGUAGE_HANDLEROID);
-		}
-		else
-			ereport(ERROR,
-					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("function %s must return type %s",
-							NameListToString(stmt->plhandler), "language_handler")));
-	}
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("function %s must return type %s",
+						NameListToString(stmt->plhandler), "language_handler")));
 
 	/* validate the inline function */
 	if (stmt->plinline)

src/backend/commands/trigger.c

@@ -694,25 +694,10 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
 	}
 	funcrettype = get_func_rettype(funcoid);
 	if (funcrettype != TRIGGEROID)
-	{
-		/*
-		 * We allow OPAQUE just so we can load old dump files.  When we see a
-		 * trigger function declared OPAQUE, change it to TRIGGER.
-		 */
-		if (funcrettype == OPAQUEOID)
-		{
-			ereport(WARNING,
-					(errmsg("changing return type of function %s from %s to %s",
-							NameListToString(stmt->funcname),
-							"opaque", "trigger")));
-			SetFunctionReturnType(funcoid, TRIGGEROID);
-		}
-		else
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
-					 errmsg("function %s must return type %s",
-							NameListToString(stmt->funcname), "trigger")));
-	}
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+				 errmsg("function %s must return type %s",
+						NameListToString(stmt->funcname), "trigger")));
 
 	/*
 	 * If it's a user-entered CREATE CONSTRAINT TRIGGER command, make a

src/backend/utils/adt/pseudotypes.c

@@ -415,7 +415,6 @@ PSEUDOTYPE_DUMMY_IO_FUNCS(fdw_handler);
 PSEUDOTYPE_DUMMY_IO_FUNCS(index_am_handler);
 PSEUDOTYPE_DUMMY_IO_FUNCS(tsm_handler);
 PSEUDOTYPE_DUMMY_IO_FUNCS(internal);
-PSEUDOTYPE_DUMMY_IO_FUNCS(opaque);
 PSEUDOTYPE_DUMMY_IO_FUNCS(anyelement);
 PSEUDOTYPE_DUMMY_IO_FUNCS(anynonarray);
 PSEUDOTYPE_DUMMY_IO_FUNCS(table_am_handler);

src/bin/pg_dump/pg_dump.c

@@ -82,10 +82,9 @@ typedef struct
 
 typedef enum OidOptions
 {
-	zeroAsOpaque = 1,
-	zeroAsAny = 2,
-	zeroAsStar = 4,
-	zeroAsNone = 8
+	zeroIsError = 1,
+	zeroAsStar = 2,
+	zeroAsNone = 4
 } OidOptions;
 
 /* global decls */
@@ -122,8 +121,6 @@ static SimpleStringList tabledata_exclude_patterns = {NULL, NULL};
 static SimpleOidList tabledata_exclude_oids = {NULL, NULL};
 
 
-char		g_opaque_type[10];	/* name for the opaque type */
-
 /* placeholders for the delimiters for comments */
 char		g_comment_start[10];
 char		g_comment_end[10];
@@ -404,7 +401,6 @@ main(int argc, char **argv)
 
 	strcpy(g_comment_start, "-- ");
 	g_comment_end[0] = '\0';
-	strcpy(g_opaque_type, "opaque");
 
 	progname = get_progname(argv[0]);
 
@@ -10736,7 +10732,7 @@ dumpBaseType(Archive *fout, TypeInfo *tyinfo)
 	{
 		char	   *elemType;
 
-		elemType = getFormattedTypeName(fout, tyinfo->typelem, zeroAsOpaque);
+		elemType = getFormattedTypeName(fout, tyinfo->typelem, zeroIsError);
 		appendPQExpBuffer(q, ",\n    ELEMENT = %s", elemType);
 		free(elemType);
 	}
@@ -11547,7 +11543,7 @@ format_function_arguments_old(Archive *fout,
 		const char *argname;
 
 		typid = allargtypes ? atooid(allargtypes[j]) : finfo->argtypes[j];
-		typname = getFormattedTypeName(fout, typid, zeroAsOpaque);
+		typname = getFormattedTypeName(fout, typid, zeroIsError);
 
 		if (argmodes)
 		{
@@ -11616,7 +11612,7 @@ format_function_signature(Archive *fout, FuncInfo *finfo, bool honor_quotes)
 			appendPQExpBufferStr(&fn, ", ");
 
 		typname = getFormattedTypeName(fout, finfo->argtypes[j],
-									   zeroAsOpaque);
+									   zeroIsError);
 		appendPQExpBufferStr(&fn, typname);
 		free(typname);
 	}
@@ -12021,7 +12017,7 @@ dumpFunc(Archive *fout, FuncInfo *finfo)
 	else
 	{
 		rettypename = getFormattedTypeName(fout, finfo->prorettype,
-										   zeroAsOpaque);
+										   zeroIsError);
 		appendPQExpBuffer(q, " RETURNS %s%s",
 						  (proretset[0] == 't') ? "SETOF " : "",
 						  rettypename);
@@ -13740,7 +13736,7 @@ format_aggregate_signature(AggInfo *agginfo, Archive *fout, bool honor_quotes)
 			char	   *typname;
 
 			typname = getFormattedTypeName(fout, agginfo->aggfn.argtypes[j],
-										   zeroAsOpaque);
+										   zeroIsError);
 
 			appendPQExpBuffer(&buf, "%s%s",
 							  (j > 0) ? ", " : "",
@@ -18363,11 +18359,7 @@ getFormattedTypeName(Archive *fout, Oid oid, OidOptions opts)
 
 	if (oid == 0)
 	{
-		if ((opts & zeroAsOpaque) != 0)
-			return pg_strdup(g_opaque_type);
-		else if ((opts & zeroAsAny) != 0)
-			return pg_strdup("'any'");
-		else if ((opts & zeroAsStar) != 0)
+		if ((opts & zeroAsStar) != 0)
 			return pg_strdup("*");
 		else if ((opts & zeroAsNone) != 0)
 			return pg_strdup("NONE");

src/bin/pg_dump/pg_dump.h

@@ -640,8 +640,6 @@ typedef struct _extensionMemberId
 extern char g_comment_start[10];
 extern char g_comment_end[10];
 
-extern char g_opaque_type[10];	/* name for the opaque type */
-
 /*
  *	common utility functions
  */

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202003031
+#define CATALOG_VERSION_NO	202003051
 
 #endif

src/include/catalog/pg_proc.dat

@@ -7054,12 +7054,6 @@
 { oid => '2305', descr => 'I/O',
   proname => 'internal_out', prorettype => 'cstring', proargtypes => 'internal',
   prosrc => 'internal_out' },
-{ oid => '2306', descr => 'I/O',
-  proname => 'opaque_in', proisstrict => 'f', prorettype => 'opaque',
-  proargtypes => 'cstring', prosrc => 'opaque_in' },
-{ oid => '2307', descr => 'I/O',
-  proname => 'opaque_out', prorettype => 'cstring', proargtypes => 'opaque',
-  prosrc => 'opaque_out' },
 { oid => '2312', descr => 'I/O',
   proname => 'anyelement_in', prorettype => 'anyelement',
   proargtypes => 'cstring', prosrc => 'anyelement_in' },
@@ -7067,10 +7061,10 @@
   proname => 'anyelement_out', prorettype => 'cstring',
   proargtypes => 'anyelement', prosrc => 'anyelement_out' },
 { oid => '2398', descr => 'I/O',
-  proname => 'shell_in', proisstrict => 'f', prorettype => 'opaque',
+  proname => 'shell_in', proisstrict => 'f', prorettype => 'void',
   proargtypes => 'cstring', prosrc => 'shell_in' },
 { oid => '2399', descr => 'I/O',
-  proname => 'shell_out', prorettype => 'cstring', proargtypes => 'opaque',
+  proname => 'shell_out', prorettype => 'cstring', proargtypes => 'void',
   prosrc => 'shell_out' },
 { oid => '2597', descr => 'I/O',
   proname => 'domain_in', proisstrict => 'f', provolatile => 's',

src/include/catalog/pg_type.dat

@@ -546,10 +546,6 @@
   typtype => 'p', typcategory => 'P', typinput => 'internal_in',
   typoutput => 'internal_out', typreceive => '-', typsend => '-',
   typalign => 'ALIGNOF_POINTER' },
-{ oid => '2282', descr => 'obsolete, deprecated pseudo-type',
-  typname => 'opaque', typlen => '4', typbyval => 't', typtype => 'p',
-  typcategory => 'P', typinput => 'opaque_in', typoutput => 'opaque_out',
-  typreceive => '-', typsend => '-', typalign => 'i' },
 { oid => '2283', descr => 'pseudo-type representing a polymorphic base type',
   typname => 'anyelement', typlen => '4', typbyval => 't', typtype => 'p',
   typcategory => 'P', typinput => 'anyelement_in',

src/include/commands/defrem.h

@@ -54,8 +54,6 @@ extern Oid	ResolveOpClass(List *opclass, Oid attrType,
 /* commands/functioncmds.c */
 extern ObjectAddress CreateFunction(ParseState *pstate, CreateFunctionStmt *stmt);
 extern void RemoveFunctionById(Oid funcOid);
-extern void SetFunctionReturnType(Oid funcOid, Oid newRetType);
-extern void SetFunctionArgType(Oid funcOid, int argIndex, Oid newArgType);
 extern ObjectAddress AlterFunction(ParseState *pstate, AlterFunctionStmt *stmt);
 extern ObjectAddress CreateCast(CreateCastStmt *stmt);
 extern void DropCastById(Oid castOid);

src/pl/plperl/plperl.c

@@ -2000,9 +2000,7 @@ plperl_validator(PG_FUNCTION_ARGS)
 	/* except for TRIGGER, EVTTRIGGER, RECORD, or VOID */
 	if (functyptype == TYPTYPE_PSEUDO)
 	{
-		/* we assume OPAQUE with no arguments means a trigger */
-		if (proc->prorettype == TRIGGEROID ||
-			(proc->prorettype == OPAQUEOID && proc->pronargs == 0))
+		if (proc->prorettype == TRIGGEROID)
 			is_trigger = true;
 		else if (proc->prorettype == EVTTRIGGEROID)
 			is_event_trigger = true;

src/pl/plpgsql/src/pl_handler.c

@@ -421,12 +421,10 @@ plpgsql_validator(PG_FUNCTION_ARGS)
 	functyptype = get_typtype(proc->prorettype);
 
 	/* Disallow pseudotype result */
-	/* except for TRIGGER, RECORD, VOID, or polymorphic */
+	/* except for TRIGGER, EVTTRIGGER, RECORD, VOID, or polymorphic */
 	if (functyptype == TYPTYPE_PSEUDO)
 	{
-		/* we assume OPAQUE with no arguments means a trigger */
-		if (proc->prorettype == TRIGGEROID ||
-			(proc->prorettype == OPAQUEOID && proc->pronargs == 0))
+		if (proc->prorettype == TRIGGEROID)
 			is_dml_trigger = true;
 		else if (proc->prorettype == EVTTRIGGEROID)
 			is_event_trigger = true;

src/pl/plpython/plpy_main.c

@@ -379,9 +379,7 @@ plpython2_inline_handler(PG_FUNCTION_ARGS)
 static bool
 PLy_procedure_is_trigger(Form_pg_proc procStruct)
 {
-	return (procStruct->prorettype == TRIGGEROID ||
-			(procStruct->prorettype == OPAQUEOID &&
-			 procStruct->pronargs == 0));
+	return (procStruct->prorettype == TRIGGEROID);
 }
 
 static void

src/test/regress/expected/create_type.out

@@ -83,8 +83,10 @@ SELECT * FROM default_test;
  zippo | 42
 (1 row)
 
+-- We need a shell type to test some CREATE TYPE failure cases with
+CREATE TYPE bogus_type;
 -- invalid: non-lowercase quoted identifiers
-CREATE TYPE case_int42 (
+CREATE TYPE bogus_type (
 	"Internallength" = 4,
 	"Input" = int42_in,
 	"Output" = int42_out,
@@ -111,6 +113,20 @@ WARNING:  type attribute "Passedbyvalue" not recognized
 LINE 7:  "Passedbyvalue"
          ^
 ERROR:  type input function must be specified
+-- invalid: input/output function incompatibility
+CREATE TYPE bogus_type (INPUT = array_in,
+    OUTPUT = array_out,
+    ELEMENT = int,
+    INTERNALLENGTH = 32);
+ERROR:  type input function array_in must return type bogus_type
+DROP TYPE bogus_type;
+-- It no longer is possible to issue CREATE TYPE without making a shell first
+CREATE TYPE bogus_type (INPUT = array_in,
+    OUTPUT = array_out,
+    ELEMENT = int,
+    INTERNALLENGTH = 32);
+ERROR:  type "bogus_type" does not exist
+HINT:  Create the type as a shell type, then create its I/O functions, then do a full CREATE TYPE.
 -- Test stand-alone composite type
 CREATE TYPE default_test_row AS (f1 text_w_default, f2 int42);
 CREATE FUNCTION get_default_test() RETURNS SETOF default_test_row AS '
@@ -137,28 +153,25 @@ 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;
--- Check type create with input/output incompatibility
-CREATE TYPE not_existing_type (INPUT = array_in,
-    OUTPUT = array_out,
-    ELEMENT = int,
-    INTERNALLENGTH = 32);
-ERROR:  function array_out(not_existing_type) does not exist
--- Check dependency transfer of opaque functions when creating a new type
-CREATE FUNCTION base_fn_in(cstring) RETURNS opaque AS 'boolin'
+-- Check dependencies are established when creating a new type
+CREATE TYPE base_type;
+CREATE FUNCTION base_fn_in(cstring) RETURNS base_type AS 'boolin'
     LANGUAGE internal IMMUTABLE STRICT;
-CREATE FUNCTION base_fn_out(opaque) RETURNS opaque AS 'boolout'
+NOTICE:  return type base_type is only a shell
+CREATE FUNCTION base_fn_out(base_type) RETURNS cstring AS 'boolout'
     LANGUAGE internal IMMUTABLE STRICT;
+NOTICE:  argument type base_type is only a shell
 CREATE TYPE base_type(INPUT = base_fn_in, OUTPUT = base_fn_out);
-WARNING:  changing argument type of function base_fn_out from "opaque" to base_type
-WARNING:  changing return type of function base_fn_in from opaque to base_type
-WARNING:  changing return type of function base_fn_out from opaque to cstring
 DROP FUNCTION base_fn_in(cstring); -- error
 ERROR:  cannot drop function base_fn_in(cstring) because other objects depend on it
 DETAIL:  type base_type depends on function base_fn_in(cstring)
 function base_fn_out(base_type) depends on type base_type
 HINT:  Use DROP ... CASCADE to drop the dependent objects too.
-DROP FUNCTION base_fn_out(opaque); -- error
-ERROR:  function base_fn_out(opaque) does not exist
+DROP FUNCTION base_fn_out(base_type); -- error
+ERROR:  cannot drop function base_fn_out(base_type) because other objects depend on it
+DETAIL:  type base_type depends on function base_fn_out(base_type)
+function base_fn_in(cstring) depends on type base_type
+HINT:  Use DROP ... CASCADE to drop the dependent objects too.
 DROP TYPE base_type; -- error
 ERROR:  cannot drop type base_type because other objects depend on it
 DETAIL:  function base_fn_in(cstring) depends on type base_type

src/test/regress/expected/opr_sanity.out

@@ -384,7 +384,7 @@ FROM pg_proc as p1
 WHERE  p1.prorettype = 'cstring'::regtype
     AND NOT EXISTS(SELECT 1 FROM pg_type WHERE typoutput = p1.oid)
     AND NOT EXISTS(SELECT 1 FROM pg_type WHERE typmodout = p1.oid)
-    AND p1.oid != 'shell_out(opaque)'::regprocedure
+    AND p1.oid != 'shell_out(void)'::regprocedure
 ORDER BY 1;
  oid  |   proname    
 ------+--------------

src/test/regress/sql/create_type.sql

@@ -84,8 +84,11 @@ INSERT INTO default_test DEFAULT VALUES;
 
 SELECT * FROM default_test;
 
+-- We need a shell type to test some CREATE TYPE failure cases with
+CREATE TYPE bogus_type;
+
 -- invalid: non-lowercase quoted identifiers
-CREATE TYPE case_int42 (
+CREATE TYPE bogus_type (
 	"Internallength" = 4,
 	"Input" = int42_in,
 	"Output" = int42_out,
@@ -94,6 +97,20 @@ CREATE TYPE case_int42 (
 	"Passedbyvalue"
 );
 
+-- invalid: input/output function incompatibility
+CREATE TYPE bogus_type (INPUT = array_in,
+    OUTPUT = array_out,
+    ELEMENT = int,
+    INTERNALLENGTH = 32);
+
+DROP TYPE bogus_type;
+
+-- It no longer is possible to issue CREATE TYPE without making a shell first
+CREATE TYPE bogus_type (INPUT = array_in,
+    OUTPUT = array_out,
+    ELEMENT = int,
+    INTERNALLENGTH = 32);
+
 -- Test stand-alone composite type
 
 CREATE TYPE default_test_row AS (f1 text_w_default, f2 int42);
@@ -119,20 +136,15 @@ DROP TYPE default_test_row CASCADE;
 
 DROP TABLE default_test;
 
--- Check type create with input/output incompatibility
-CREATE TYPE not_existing_type (INPUT = array_in,
-    OUTPUT = array_out,
-    ELEMENT = int,
-    INTERNALLENGTH = 32);
-
--- Check dependency transfer of opaque functions when creating a new type
-CREATE FUNCTION base_fn_in(cstring) RETURNS opaque AS 'boolin'
+-- Check dependencies are established when creating a new type
+CREATE TYPE base_type;
+CREATE FUNCTION base_fn_in(cstring) RETURNS base_type AS 'boolin'
     LANGUAGE internal IMMUTABLE STRICT;
-CREATE FUNCTION base_fn_out(opaque) RETURNS opaque AS 'boolout'
+CREATE FUNCTION base_fn_out(base_type) RETURNS cstring AS 'boolout'
     LANGUAGE internal IMMUTABLE STRICT;
 CREATE TYPE base_type(INPUT = base_fn_in, OUTPUT = base_fn_out);
 DROP FUNCTION base_fn_in(cstring); -- error
-DROP FUNCTION base_fn_out(opaque); -- error
+DROP FUNCTION base_fn_out(base_type); -- error
 DROP TYPE base_type; -- error
 DROP TYPE base_type CASCADE;
 

src/test/regress/sql/opr_sanity.sql

@@ -309,7 +309,7 @@ FROM pg_proc as p1
 WHERE  p1.prorettype = 'cstring'::regtype
     AND NOT EXISTS(SELECT 1 FROM pg_type WHERE typoutput = p1.oid)
     AND NOT EXISTS(SELECT 1 FROM pg_type WHERE typmodout = p1.oid)
-    AND p1.oid != 'shell_out(opaque)'::regprocedure
+    AND p1.oid != 'shell_out(void)'::regprocedure
 ORDER BY 1;
 
 -- Check for length inconsistencies between the various argument-info arrays.