| Message ID | 87zk1qasvv.fsf@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Fri, Dec 7, 2012 at 7:33 AM, Dodji Seketeli <dodji@redhat.com> wrote: > Jason Merrill <jason@redhat.com> writes: > >> Oops, thought I had sent this before. > > No problem. Thank you for replying now× > >> On 11/17/2012 10:23 AM, Dodji Seketeli wrote: >> > - if (cp_parser_parse_definitely (parser)) >> > + /* Note that if we actually see the '=' token after the >> > + identifier, cp_parser_alias_declaration commits the >> > + tentative parse. In that case, we really expects an >> > + alias-declaration. Otherwise, we expect a using >> > + declaration. */ >> > + alias_decl_expected = >> > + !cp_parser_uncommitted_to_tentative_parse_p (parser); >> > + cp_parser_parse_definitely (parser); >> >> Maybe just check whether decl is error_mark_node? > > As we further discussed this on IRC, when cp_parser_alias_declaration > returns error_mark_node, it is either because we encountered an error > before the hypothetical '=', in which case we might want to try to > parse a using declaration, or it is because we encountered an error > after the the '=', in which case we committed to parsing an alias > declaration and we must emit a hard error. > > And I believe what we want here is to tell the two possible cases > apart. Yes! > >> >> > + if (type == error_mark_node) >> > + return error_mark_node; >> >> I think for error-recovery we might want to >> cp_parser_skip_to_end_of_block_or_statement as well. > > Right, done. > > Bootstrapped and tested on x86_64-unknown-linux-gnu against trunk. > > gcc/cp/ > > * parser.c (cp_parser_alias_declaration): Commit to tentative > parse when see the '=' token. Get out if the type-id is invalid. > Update function comment. > (cp_parser_member_declaration): Don't try to parse a using > declaration if we know that we expected an alias declaration; that > is, if we see the '=' token after the identifier. > > gcc/testsuite/ > > * g++.dg/cpp0x/alias-decl-28.C: New test. > * g++.dg/cpp0x/alias-decl-16.C: Update. > --- > gcc/cp/parser.c | 31 +++++++++++++++++++++++++++--- > gcc/testsuite/g++.dg/cpp0x/alias-decl-16.C | 2 +- > gcc/testsuite/g++.dg/cpp0x/alias-decl-28.C | 7 +++++++ > 3 files changed, 36 insertions(+), 4 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-28.C > > diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c > index a010f1f..c39ef30 100644 > --- a/gcc/cp/parser.c > +++ b/gcc/cp/parser.c > @@ -15262,7 +15262,11 @@ cp_parser_using_declaration (cp_parser* parser, > /* Parse an alias-declaration. > > alias-declaration: > - using identifier attribute-specifier-seq [opt] = type-id */ > + using identifier attribute-specifier-seq [opt] = type-id > + > + Note that if this function is used in the context of a tentative > + parse, it commits the currently active tentative parse after it > + sees the '=' token. */ This comment is repeated below; I don't think it is necessary or should be part of the specification. In general we don't (and shouldn't) say this unless a parsing function deviates from the general parsing strategy -- this one doesn't. > > static tree > cp_parser_alias_declaration (cp_parser* parser) > @@ -15295,6 +15299,8 @@ cp_parser_alias_declaration (cp_parser* parser) > if (cp_parser_error_occurred (parser)) > return error_mark_node; > > + cp_parser_commit_to_tentative_parse (parser); > + > /* Now we are going to parse the type-id of the declaration. */ > > /* > @@ -15324,10 +15330,19 @@ cp_parser_alias_declaration (cp_parser* parser) > if (parser->num_template_parameter_lists) > parser->type_definition_forbidden_message = saved_message; > > + if (type == error_mark_node) > + { > + cp_parser_skip_to_end_of_block_or_statement (parser); > + return error_mark_node; > + } > + > cp_parser_require (parser, CPP_SEMICOLON, RT_SEMICOLON); > > if (cp_parser_error_occurred (parser)) > - return error_mark_node; > + { > + cp_parser_skip_to_end_of_block_or_statement (parser); > + return error_mark_node; > + } > > /* A typedef-name can also be introduced by an alias-declaration. The > identifier following the using keyword becomes a typedef-name. It has > @@ -19063,9 +19078,19 @@ cp_parser_member_declaration (cp_parser* parser) > else > { > tree decl; > + bool alias_decl_expected; > cp_parser_parse_tentatively (parser); > decl = cp_parser_alias_declaration (parser); > - if (cp_parser_parse_definitely (parser)) > + /* Note that if we actually see the '=' token after the > + identifier, cp_parser_alias_declaration commits the > + tentative parse. In that case, we really expects an > + alias-declaration. Otherwise, we expect a using > + declaration. */ > + alias_decl_expected = > + !cp_parser_uncommitted_to_tentative_parse_p (parser); > + cp_parser_parse_definitely (parser); > + > + if (alias_decl_expected) > finish_member_declaration (decl); > else > cp_parser_using_declaration (parser, > diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-16.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-16.C > index d66660a..ce6ad0a 100644 > --- a/gcc/testsuite/g++.dg/cpp0x/alias-decl-16.C > +++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-16.C > @@ -23,6 +23,6 @@ template<class T> > using A3 = > enum B3 {b = 0;}; //{ dg-error "types may not be defined in alias template" } > > -A3<int> a3; > +A3<int> a3; // { dg-error "'A3' does not name a type" } > > int main() { } > diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-28.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-28.C > new file mode 100644 > index 0000000..086b5e5 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-28.C > @@ -0,0 +1,7 @@ > +// Origin: PR c++/54401 > +// { dg-do compile { target c++11 } } > + > +template<typename> > +struct X { > + using type = T; // { dg-error "expected type-specifier|does not name a type" } > +}; > -- > 1.7.11.7 > > > -- > Dodji Sound good to me (except for the comment). thanks! -- Gaby
On 12/07/2012 08:42 AM, Gabriel Dos Reis wrote:
> Sound good to me (except for the comment).
Me, too.
Jason
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index a010f1f..c39ef30 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -15262,7 +15262,11 @@ cp_parser_using_declaration (cp_parser* parser, /* Parse an alias-declaration. alias-declaration: - using identifier attribute-specifier-seq [opt] = type-id */ + using identifier attribute-specifier-seq [opt] = type-id + + Note that if this function is used in the context of a tentative + parse, it commits the currently active tentative parse after it + sees the '=' token. */ static tree cp_parser_alias_declaration (cp_parser* parser) @@ -15295,6 +15299,8 @@ cp_parser_alias_declaration (cp_parser* parser) if (cp_parser_error_occurred (parser)) return error_mark_node; + cp_parser_commit_to_tentative_parse (parser); + /* Now we are going to parse the type-id of the declaration. */ /* @@ -15324,10 +15330,19 @@ cp_parser_alias_declaration (cp_parser* parser) if (parser->num_template_parameter_lists) parser->type_definition_forbidden_message = saved_message; + if (type == error_mark_node) + { + cp_parser_skip_to_end_of_block_or_statement (parser); + return error_mark_node; + } + cp_parser_require (parser, CPP_SEMICOLON, RT_SEMICOLON); if (cp_parser_error_occurred (parser)) - return error_mark_node; + { + cp_parser_skip_to_end_of_block_or_statement (parser); + return error_mark_node; + } /* A typedef-name can also be introduced by an alias-declaration. The identifier following the using keyword becomes a typedef-name. It has @@ -19063,9 +19078,19 @@ cp_parser_member_declaration (cp_parser* parser) else { tree decl; + bool alias_decl_expected; cp_parser_parse_tentatively (parser); decl = cp_parser_alias_declaration (parser); - if (cp_parser_parse_definitely (parser)) + /* Note that if we actually see the '=' token after the + identifier, cp_parser_alias_declaration commits the + tentative parse. In that case, we really expects an + alias-declaration. Otherwise, we expect a using + declaration. */ + alias_decl_expected = + !cp_parser_uncommitted_to_tentative_parse_p (parser); + cp_parser_parse_definitely (parser); + + if (alias_decl_expected) finish_member_declaration (decl); else cp_parser_using_declaration (parser, diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-16.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-16.C index d66660a..ce6ad0a 100644 --- a/gcc/testsuite/g++.dg/cpp0x/alias-decl-16.C +++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-16.C @@ -23,6 +23,6 @@ template<class T> using A3 = enum B3 {b = 0;}; //{ dg-error "types may not be defined in alias template" } -A3<int> a3; +A3<int> a3; // { dg-error "'A3' does not name a type" } int main() { } diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-28.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-28.C new file mode 100644 index 0000000..086b5e5 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-28.C @@ -0,0 +1,7 @@ +// Origin: PR c++/54401 +// { dg-do compile { target c++11 } } + +template<typename> +struct X { + using type = T; // { dg-error "expected type-specifier|does not name a type" } +};