Hi! The C++26 P2662R3 Pack indexing paper mentions that both GCC and MSVC don't handle T...[10] parameter declaration when T is a pack. While that will change meaning in C++26, in C++11 .. C++23 this ought to be valid. Also, T...(args) as well.
The following patch handles those in cp_parser_direct_declarator. Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2024-05-09 Jakub Jelinek <ja...@redhat.com> PR c++/115012 * parser.cc (cp_parser_direct_declarator): Handle abstract declarator starting with ... followed by [ or (. * g++.dg/cpp0x/variadic185.C: New test. * g++.dg/cpp0x/variadic186.C: New test. --- gcc/cp/parser.cc.jj 2024-05-09 10:30:58.000000000 +0200 +++ gcc/cp/parser.cc 2024-05-09 16:44:01.250777325 +0200 @@ -23916,7 +23916,12 @@ cp_parser_direct_declarator (cp_parser* { /* Peek at the next token. */ token = cp_lexer_peek_token (parser->lexer); - if (token->type == CPP_OPEN_PAREN) + if (token->type == CPP_OPEN_PAREN + || (first + && dcl_kind != CP_PARSER_DECLARATOR_NAMED + && token->type == CPP_ELLIPSIS + && cxx_dialect > cxx98 + && cp_lexer_nth_token_is (parser->lexer, 2, CPP_OPEN_PAREN))) { /* This is either a parameter-declaration-clause, or a parenthesized declarator. When we know we are parsing a @@ -23955,6 +23960,11 @@ cp_parser_direct_declarator (cp_parser* Thus again, we try a parameter-declaration-clause, and if that fails, we back out and return. */ + bool pack_expansion_p = token->type == CPP_ELLIPSIS; + + if (pack_expansion_p) + /* Consume the `...' */ + cp_lexer_consume_token (parser->lexer); if (!first || dcl_kind != CP_PARSER_DECLARATOR_NAMED) { @@ -24098,6 +24108,7 @@ cp_parser_direct_declarator (cp_parser* attrs, parens_loc); declarator->attributes = gnu_attrs; + declarator->parameter_pack_p |= pack_expansion_p; /* Any subsequent parameter lists are to do with return type, so are not those of the declared function. */ @@ -24121,7 +24132,7 @@ cp_parser_direct_declarator (cp_parser* /* If this is the first, we can try a parenthesized declarator. */ - if (first) + if (first && !pack_expansion_p) { bool saved_in_type_id_in_expr_p; @@ -24156,16 +24167,27 @@ cp_parser_direct_declarator (cp_parser* else break; } - else if ((!first || dcl_kind != CP_PARSER_DECLARATOR_NAMED) - && token->type == CPP_OPEN_SQUARE - && !cp_next_tokens_can_be_attribute_p (parser)) + else if (((!first || dcl_kind != CP_PARSER_DECLARATOR_NAMED) + && token->type == CPP_OPEN_SQUARE + && !cp_next_tokens_can_be_attribute_p (parser)) + || (first + && dcl_kind != CP_PARSER_DECLARATOR_NAMED + && token->type == CPP_ELLIPSIS + && cp_lexer_nth_token_is (parser->lexer, 2, CPP_OPEN_SQUARE) + && cxx_dialect > cxx98 + && !cp_nth_tokens_can_be_std_attribute_p (parser, 2))) { /* Parse an array-declarator. */ tree bounds, attrs; + bool pack_expansion_p = token->type == CPP_ELLIPSIS; if (ctor_dtor_or_conv_p) *ctor_dtor_or_conv_p = 0; + if (pack_expansion_p) + /* Consume the `...' */ + cp_lexer_consume_token (parser->lexer); + open_paren = NULL; first = false; parser->default_arg_ok_p = false; @@ -24220,6 +24242,7 @@ cp_parser_direct_declarator (cp_parser* attrs = cp_parser_std_attribute_spec_seq (parser); declarator = make_array_declarator (declarator, bounds); declarator->std_attributes = attrs; + declarator->parameter_pack_p |= pack_expansion_p; } else if (first && dcl_kind != CP_PARSER_DECLARATOR_ABSTRACT) { --- gcc/testsuite/g++.dg/cpp0x/variadic185.C.jj 2024-05-09 15:08:49.070651189 +0200 +++ gcc/testsuite/g++.dg/cpp0x/variadic185.C 2024-05-09 15:07:40.045583153 +0200 @@ -0,0 +1,39 @@ +// PR c++/115012 +// { dg-do compile { target { c++11 && c++23_down } } } +// { dg-final { scan-assembler "_Z3fooILi10EJidEEvDpAT__T0_" } } +// { dg-final { scan-assembler "_Z3barILi10EiEvPT0_" } } +// { dg-final { scan-assembler "_Z3bazILi10EJidEEvDpAT__T0_" } } +// { dg-final { scan-assembler "_Z3quxILi5EJifEEvDpAT__AT__T0_" } } + +template <int N, typename ...T> +void +foo (T... x[N]) +{ +} + +template <int N, typename T> +void +bar (T [N]) +{ +} + +template <int N, typename ...T> +void +baz (T... [N]) +{ +} + +template <int N, typename ...T> +void +qux (T... [N][N]) +{ +} + +void +corge (int a[10], double b[10], int c[5][5], float d[5][5]) +{ + foo <10, int, double> (a, b); + bar <10, int> (a); + baz <10, int, double> (a, b); + qux <5, int, float> (c, d); +} --- gcc/testsuite/g++.dg/cpp0x/variadic186.C.jj 2024-05-09 16:39:50.409153099 +0200 +++ gcc/testsuite/g++.dg/cpp0x/variadic186.C 2024-05-09 15:37:22.469569809 +0200 @@ -0,0 +1,43 @@ +// PR c++/115012 +// { dg-do compile { target { c++11 } } } +// { dg-final { scan-assembler "_Z3fooIJidEEvDpFT_iE" } } +// { dg-final { scan-assembler "_Z3barIiEvPFT_iE" } } +// { dg-final { scan-assembler "_Z3bazIJidEEvDpFT_iE" } } + +template <typename ...T> +void +foo (T... x (int)) +{ +} + +template <typename T> +void +bar (T (int)) +{ +} + +template <typename ...T> +void +baz (T... (int)) +{ +} + +int +f1 (int) +{ + return 0; +} + +double +f2 (int) +{ + return 0; +} + +void +corge () +{ + foo <int, double> (f1, f2); + bar <int> (f1); + baz <int, double> (f1, f2); +} Jakub