On Tue, Jan 26, 2016 at 11:31 AM, Patrick Palka <patr...@parcs.ath.cx> wrote:
> This patch makes the parser more robust in determining whether an 'auto'
> specifier that appears in a parameter declaration corresponds to a
> placeholder for a late return type, or corresponds to an implicit
> template parameter as for an abbreviated function template.
>
> Bootstrap + regtest in progress on x86_64-pc-linux-gnu, will also test
> this change against Boost. OK to commit if testing succeeds? What
> about for GCC 4.9/5?
>
> gcc/cp/ChangeLog:
>
> PR c++/69139
> * parser.c (cp_parser_simple_type_specifier): Make the check
> for disambiguating between an 'auto' placeholder and an implicit
> template parameter more robust.
>
> gcc/testsuite/ChangeLog:
>
> PR c++/69139
> * g++.dg/cpp0x/auto47.C: New test.
> ---
> gcc/cp/parser.c | 33 +++++++++++++++++++++++----------
> gcc/testsuite/g++.dg/cpp0x/auto47.C | 20 ++++++++++++++++++++
> 2 files changed, 43 insertions(+), 10 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/auto47.C
>
> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
> index d03b0c9..56c834f 100644
> --- a/gcc/cp/parser.c
> +++ b/gcc/cp/parser.c
> @@ -16032,20 +16032,33 @@ cp_parser_simple_type_specifier (cp_parser* parser,
> /* The 'auto' might be the placeholder return type for a function
> decl
> with trailing return type. */
> bool have_trailing_return_fn_decl = false;
> - if (cp_lexer_peek_nth_token (parser->lexer, 2)->type
> - == CPP_OPEN_PAREN)
> +
> + cp_parser_parse_tentatively (parser);
> + cp_lexer_consume_token (parser->lexer);
> + while (cp_lexer_next_token_is_not (parser->lexer, CPP_EQ)
> + && cp_lexer_next_token_is_not (parser->lexer, CPP_COMMA)
> + && cp_lexer_next_token_is_not (parser->lexer,
> CPP_CLOSE_PAREN)
> + && cp_lexer_next_token_is_not (parser->lexer, CPP_EOF))
> {
> - cp_parser_parse_tentatively (parser);
> - cp_lexer_consume_token (parser->lexer);
> - cp_lexer_consume_token (parser->lexer);
> - if (cp_parser_skip_to_closing_parenthesis (parser,
> + if (cp_lexer_next_token_is (parser->lexer, CPP_OPEN_PAREN))
> + {
> + cp_lexer_consume_token (parser->lexer);
> + cp_parser_skip_to_closing_parenthesis (parser,
> /*recovering*/false,
> /*or_comma*/false,
> -
> /*consume_paren*/true))
> - have_trailing_return_fn_decl
> - = cp_lexer_next_token_is (parser->lexer, CPP_DEREF);
> - cp_parser_abort_tentative_parse (parser);
> +
> /*consume_paren*/true);
> + continue;
> + }
> +
> + if (cp_lexer_next_token_is (parser->lexer, CPP_DEREF))
> + {
> + have_trailing_return_fn_decl = true;
> + break;
> + }
> +
> + cp_lexer_consume_token (parser->lexer);
> }
> + cp_parser_abort_tentative_parse (parser);
>
> if (have_trailing_return_fn_decl)
> {
> diff --git a/gcc/testsuite/g++.dg/cpp0x/auto47.C
> b/gcc/testsuite/g++.dg/cpp0x/auto47.C
> new file mode 100644
> index 0000000..08adf31
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/auto47.C
> @@ -0,0 +1,20 @@
> +// PR c++/69139
> +// { dg-do compile { target c++11 } }
> +
> +auto get(int) -> int { return {}; }
> +template <class R> int f(auto (*)(int) -> R) { return {}; }
> +int i = f(get);
> +
> +int foo1 (auto (int) -> char);
> +
> +int foo2 (auto f(int) -> char);
> +
> +int foo2 (auto (f)(int) -> char);
> +
> +int foo3 (auto (*f)(int) -> char);
> +
> +int foo4 (auto (*const **&f)(int) -> char);
> +
> +int foo5 (auto (*const **&f)(int, int *) -> char);
> +
> +int foo6 (auto (int) const -> char); // { dg-error "const" }
> --
> 2.7.0.134.gf5046bd.dirty
>
Ping.
