https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113929
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
This is IMHO different, because the grammar is:
template-parameter:
type-parameter
parameter-declaration
parameter-declaration:
attribute-specifier-seq[opt] this[opt] decl-specifier-seq declarator
attribute-specifier-seq[opt] decl-specifier-seq declarator =
initializer-clause
attribute-specifier-seq[opt] this[opt] decl-specifier-seq
abstract-declarator[opt]
attribute-specifier-seq[opt] decl-specifier-seq abstract-declarator[opt] =
initializer-clause
So, unlike the other cases, the grammar allows this specifier in there, just
https://eel.is/c++draft/dcl.fct#6 says it is invalid, because it is not the
first parameter-declaration of a parameter-declaration-list (because it is a
parameter-declaration of a template-parameter-list instead).
I'd go with (on top of PR113802 fix):
2024-02-15 Jakub Jelinek <ja...@redhat.com>
PR c++/113929
* parser.cc (cp_parser_parameter_declaration): Diagnose this specifier
on template parameter declaration.
* g++.dg/parse/pr113929.C: New test.
--- gcc/cp/parser.cc.jj 2024-02-15 17:33:11.641453437 +0100
+++ gcc/cp/parser.cc 2024-02-15 17:40:29.592447265 +0100
@@ -25724,8 +25724,15 @@ cp_parser_parameter_declaration (cp_pars
for a C-style variadic function. */
token = cp_lexer_peek_token (parser->lexer);
- bool const xobj_param_p
+ bool xobj_param_p
= decl_spec_seq_has_spec_p (&decl_specifiers, ds_this);
+ if (xobj_param_p && template_parm_p)
+ {
+ error_at (decl_specifiers.locations[ds_this],
+ "%<this%> specifier in template parameter declaration");
+ xobj_param_p = false;
+ decl_specifiers.locations[ds_this] = 0;
+ }
bool diag_xobj_parameter_pack = false;
if (xobj_param_p && (declarator && declarator->parameter_pack_p))
--- gcc/testsuite/g++.dg/parse/pr113929.C.jj 2024-02-15 17:43:18.500129688
+0100
+++ gcc/testsuite/g++.dg/parse/pr113929.C 2024-02-15 17:42:54.564458109
+0100
@@ -0,0 +1,7 @@
+// PR c++/113929
+// { dg-do compile }
+
+template <this int C> // { dg-error "'this' specifier in template
parameter declaration" }
+struct S {};
+template <int N, this int C> // { dg-error "'this' specifier in template
parameter declaration" }
+struct T {};
