On 8/15/24 4:58 PM, Jakub Jelinek wrote:
Hi!
For C++ 26 P2552R3 I went through all the spots (except modules) where
attribute-specifier-seq appears in the grammar and tried to construct
a testcase in all those spots, for now for [[deprecated]] attribute.
The fourth issue is that we just emit (when enabled) -Wextra-semi warning
not just for lone semicolon at class scope (correct), but also for
[[]]; or [[whatever]]; there too.
While just semicolon is valid in C++11 and newer,
https://eel.is/c++draft/class.mem#nt:member-declaration
allows empty-declaration, unlike namespace scope or block scope
something like attribute-declaration or empty statement with attributes
applied for it aren't supported.
While syntactically it matches
attribute-specifier-seq [opt] decl-specifier-seq [opt] member-declarator-list
[opt] ;
with the latter two omitted, there is
https://eel.is/c++draft/class.mem#general-3
which says that is not valid.
So, the following patch emits a pedwarn in that case.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK
2024-08-15 Jakub Jelinek <ja...@redhat.com>
PR c++/110345
* parser.cc (cp_parser_member_declaration): Call maybe_warn_extra_semi
only if it is empty-declaration, if there are some tokens like
attribute, pedwarn that the declaration doesn't declare anything.
* g++.dg/cpp0x/gen-attrs-84.C: New test.
--- gcc/cp/parser.cc.jj 2024-08-15 18:00:33.202211372 +0200
+++ gcc/cp/parser.cc 2024-08-15 18:56:12.254139651 +0200
@@ -28268,7 +28268,11 @@ cp_parser_member_declaration (cp_parser*
if (!decl_specifiers.any_specifiers_p)
{
cp_token *token = cp_lexer_peek_token (parser->lexer);
- maybe_warn_extra_semi (token->location, extra_semi_kind::member);
+ if (decl_spec_token_start == token)
+ maybe_warn_extra_semi (token->location, extra_semi_kind::member);
+ else
+ pedwarn (decl_spec_token_start->location, OPT_Wpedantic,
+ "declaration does not declare anything");
}
else
{
--- gcc/testsuite/g++.dg/cpp0x/gen-attrs-84.C.jj 2024-08-15
19:00:02.540314537 +0200
+++ gcc/testsuite/g++.dg/cpp0x/gen-attrs-84.C 2024-08-15 19:05:36.602231553
+0200
@@ -0,0 +1,8 @@
+// { dg-do compile { target c++11 } }
+
+struct A {
+ [[]]; // { dg-error "declaration does not declare
anything" }
+};
+struct B {
+ [[gnu::deprecated]]; // { dg-error "declaration does not declare anything" }
+};
Jakub
