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"); + 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 +{ +} Jakub
