On 7/29/21 5:28 AM, Jakub Jelinek wrote:
On Wed, Jul 28, 2021 at 04:32:08PM -0400, Jason Merrill wrote:
As the following testcase shows, we don't parse properly
C++11 attribute-declaration:
https://eel.is/c++draft/dcl.dcl#nt:attribute-declaration
cp_parser_toplevel_declaration just handles empty-declaration parsing
(with diagnostics for C++98)
This seems to be a bug: from the comments, cp_parser_toplevel_declaration is
intended to only handle #pragma parsing, everything else should be in
cp_parser_declaration.
As a result, we wrongly reject
extern "C" ;
So please move empty-declaration and attribute-declaration handling into
cp_parser_declaration.
So like this?
It means we allow for modules
export ;
or
export [[]];
where we previously rejected those, which is allowed by the grammar and
invalid because of
https://eel.is/c++draft/module.interface#3
but we allowed already before
export {}
which suffers from the same problem - the export-declaration doesn't declare
at least one name. So I think there just should be something that tracks if
the module exported at least one name and if not, diagnose it at the end of
cp_parser_module_export (and adjust the new modules testcase).
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2021-07-29 Jakub Jelinek <ja...@redhat.com>
PR c++/101582
* parser.c (cp_parser_skip_std_attribute_spec_seq): Add a forward
declaration.
(cp_parser_declaration): Parse empty-declaration and
attribute-declaration.
(cp_parser_toplevel_declaration): Don't parse empty-declaration here.
* g++.dg/cpp0x/gen-attrs-45.C: Expect a warning about ignored
attributes instead of error.
* g++.dg/cpp0x/gen-attrs-75.C: New test.
* g++.dg/modules/pr101582-1.C: New test.
--- gcc/cp/parser.c.jj 2021-07-28 23:06:38.658443554 +0200
+++ gcc/cp/parser.c 2021-07-28 23:12:10.955941089 +0200
@@ -2507,6 +2507,8 @@ static tree cp_parser_std_attribute_spec
(cp_parser *);
static tree cp_parser_std_attribute_spec_seq
(cp_parser *);
+static size_t cp_parser_skip_std_attribute_spec_seq
+ (cp_parser *, size_t);
static size_t cp_parser_skip_attributes_opt
(cp_parser *, size_t);
static bool cp_parser_extension_opt
@@ -14410,6 +14412,31 @@ cp_parser_declaration (cp_parser* parser
cp_token *token2 = (token1->type == CPP_EOF
? token1 : cp_lexer_peek_nth_token (parser->lexer, 2));
+ if (token1->type == CPP_SEMICOLON)
+ {
+ cp_lexer_consume_token (parser->lexer);
+ /* A declaration consisting of a single semicolon is invalid
+ * before C++11. Allow it unless we're being pedantic. */
+ if (cxx_dialect < cxx11)
+ pedwarn (input_location, OPT_Wpedantic, "extra %<;%>");
+ return;
+ }
+ else if (cp_lexer_nth_token_is (parser->lexer,
+ cp_parser_skip_std_attribute_spec_seq (parser,
+ 1),
+ CPP_SEMICOLON))
+ {
+ location_t attrs_loc = token1->location;
+ tree std_attrs = cp_parser_std_attribute_spec_seq (parser);
+ if (std_attrs != NULL_TREE)
+ warning_at (make_location (attrs_loc, attrs_loc, parser->lexer),
+ OPT_Wattributes,
+ "attributes in attribute declaration are ignored");
Let's not mention the obscure attribute-declaration grammar nonterminal,
"attribute ignored" seems sufficient.
+ if (cp_lexer_next_token_is (parser->lexer, CPP_SEMICOLON))
+ cp_lexer_consume_token (parser->lexer);
+ return;
+ }
+
/* Get the high-water mark for the DECLARATOR_OBSTACK. */
void *p = obstack_alloc (&declarator_obstack, 0);
@@ -14560,14 +14587,6 @@ cp_parser_toplevel_declaration (cp_parse
cp_parser_declaration. (A #pragma at block scope is
handled in cp_parser_statement.) */
cp_parser_pragma (parser, pragma_external, NULL);
- else if (token->type == CPP_SEMICOLON)
- {
- cp_lexer_consume_token (parser->lexer);
- /* A declaration consisting of a single semicolon is invalid
- * before C++11. Allow it unless we're being pedantic. */
- if (cxx_dialect < cxx11)
- pedwarn (input_location, OPT_Wpedantic, "extra %<;%>");
- }
else
/* Parse the declaration itself. */
cp_parser_declaration (parser, NULL_TREE);
--- gcc/testsuite/g++.dg/cpp0x/gen-attrs-45.C.jj 2021-07-26
09:13:08.504121494 +0200
+++ gcc/testsuite/g++.dg/cpp0x/gen-attrs-45.C 2021-07-28 23:07:05.095085351
+0200
@@ -1,4 +1,4 @@
// PR c++/52906
// { dg-do compile { target c++11 } }
-[[gnu::deprecated]]; // { dg-error "does not declare anything" }
+[[gnu::deprecated]]; // { dg-warning "attributes in attribute declaration are
ignored" }
--- gcc/testsuite/g++.dg/cpp0x/gen-attrs-75.C.jj 2021-07-28
23:07:05.095085351 +0200
+++ gcc/testsuite/g++.dg/cpp0x/gen-attrs-75.C 2021-07-29 10:59:09.630326797
+0200
@@ -0,0 +1,35 @@
+// PR c++/101582
+// { dg-do compile }
+// { dg-options "" }
+
+;
+[[]] [[]] [[]]; // { dg-warning "attributes only available with" "" {
target c++98_only } }
+[[foobar]]; // { dg-warning "attributes in attribute declaration are
ignored" }
+// { dg-warning "attributes only available with" "" { target c++98_only } .-1 }
+
+extern "C" ;
+extern "C" [[]]; // { dg-warning "attributes only available with" "" {
target c++98_only } }
+extern "C" extern "C" ;
+extern "C" extern "C" [[]][[]][[]]; // { dg-warning "attributes only available
with" "" { target c++98_only } }
+__extension__ ;
+__extension__ [[]]; // { dg-warning "attributes only available with"
"" { target c++98_only } }
+__extension__ __extension__ ;
+__extension__ __extension__ [[]][[]]; // { dg-warning "attributes only available with"
"" { target c++98_only } }
+
+namespace N {
+
+;
+[[]] [[]] [[]]; // { dg-warning "attributes only available with" "" {
target c++98_only } }
+[[foobar]]; // { dg-warning "attributes in attribute declaration are
ignored" }
+// { dg-warning "attributes only available with" "" { target c++98_only } .-1 }
+
+extern "C" ;
+extern "C" [[]]; // { dg-warning "attributes only available with" "" {
target c++98_only } }
+extern "C" extern "C" ;
+extern "C" extern "C" [[]][[]][[]]; // { dg-warning "attributes only available
with" "" { target c++98_only } }
+__extension__ ;
+__extension__ [[]]; // { dg-warning "attributes only available with"
"" { target c++98_only } }
+__extension__ __extension__ ;
+__extension__ __extension__ [[]][[]]; // { dg-warning "attributes only available with"
"" { target c++98_only } }
+
+}
--- gcc/testsuite/g++.dg/modules/pr101582-1.C.jj 2021-07-29
11:07:17.567662550 +0200
+++ gcc/testsuite/g++.dg/modules/pr101582-1.C 2021-07-29 11:08:02.297051638
+0200
@@ -0,0 +1,9 @@
+// PR c++/101582
+// { dg-additional-options "-fmodules-ts" }
+export module pr101582;
+// { dg-module-cmi "pr101582" }
+export ;
+export [[]];
+export
+{
+}
These should have xfailed dg-errors.
OK with those changes.
Jason
