On 12/14/23 16:02, Marek Polacek wrote:
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
OK.
-- >8 -- This is sort of like r14-5514, but at block scope. Consider struct A { A(int, int); }; void g (int a) { A bar(auto(a), 42); // not a fn decl } where we emit error: 'auto' parameter not permitted in this context which is bogus -- bar doesn't declare a function, so the auto is OK, but we don't know it till we've seen the second argument. The error comes from grokdeclarator invoked just after we've parsed the auto(a). A possible approach seems to be to delay the auto parameter checking and only check once we know we are indeed dealing with a function declaration. For tparms, we should still emit the error right away. PR c++/112482 gcc/cp/ChangeLog: * decl.cc (grokdeclarator): Do not issue the auto parameter error while tentatively parsing a function parameter. * parser.cc (cp_parser_parameter_declaration_clause): Check it here. gcc/testsuite/ChangeLog: * g++.dg/cpp23/auto-fncast15.C: New test. --- gcc/cp/decl.cc | 13 +++++++++++-- gcc/cp/parser.cc | 17 +++++++++++++++-- gcc/testsuite/g++.dg/cpp23/auto-fncast15.C | 21 +++++++++++++++++++++ 3 files changed, 47 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp23/auto-fncast15.C diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc index 4d17ead123a..1ffe4c82748 100644 --- a/gcc/cp/decl.cc +++ b/gcc/cp/decl.cc @@ -14203,6 +14203,7 @@ grokdeclarator (const cp_declarator *declarator, tree auto_node = type_uses_auto (type); if (auto_node && !(cxx_dialect >= cxx17 && template_parm_flag)) { + bool err_p = true; if (cxx_dialect >= cxx14) { if (decl_context == PARM && AUTO_IS_DECLTYPE (auto_node)) @@ -14221,13 +14222,21 @@ grokdeclarator (const cp_declarator *declarator, "abbreviated function template"); inform (DECL_SOURCE_LOCATION (c), "%qD declared here", c); } - else + else if (decl_context == CATCHPARM || template_parm_flag) error_at (typespec_loc, "%<auto%> parameter not permitted in this context"); + else + /* Do not issue an error while tentatively parsing a function + parameter: for T t(auto(a), 42);, when we just saw the 1st + parameter, we don't know yet that this construct won't be + a function declaration. Defer the checking to + cp_parser_parameter_declaration_clause. */ + err_p = false; } else error_at (typespec_loc, "parameter declared %<auto%>"); - type = error_mark_node; + if (err_p) + type = error_mark_node; }/* A parameter declared as an array of T is really a pointer to T.diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc index 58e910d64af..e4fbab1bab5 100644 --- a/gcc/cp/parser.cc +++ b/gcc/cp/parser.cc @@ -25102,8 +25102,21 @@ cp_parser_parameter_declaration_clause (cp_parser* parser, committed yet, nor should we. Pushing here will detect the error of redefining a parameter. */ if (cp_lexer_next_token_is (parser->lexer, CPP_CLOSE_PAREN)) - for (tree p : pending_decls) - pushdecl (p); + { + for (tree p : pending_decls) + pushdecl (p); + + /* Delayed checking of auto parameters. */ + if (!parser->auto_is_implicit_function_template_parm_p + && cxx_dialect >= cxx14) + for (tree p = parameters; p; p = TREE_CHAIN (p)) + if (type_uses_auto (TREE_TYPE (TREE_VALUE (p)))) + { + error_at (location_of (TREE_VALUE (p)), + "%<auto%> parameter not permitted in this context"); + TREE_TYPE (TREE_VALUE (p)) = error_mark_node; + } + }/* Finish the parameter list. */if (!ellipsis_p) diff --git a/gcc/testsuite/g++.dg/cpp23/auto-fncast15.C b/gcc/testsuite/g++.dg/cpp23/auto-fncast15.C new file mode 100644 index 00000000000..deb1efcc46c --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp23/auto-fncast15.C @@ -0,0 +1,21 @@ +// PR c++/112482 +// { dg-do compile { target c++23 } } +// { dg-options "-Wno-vexing-parse" } + +void foo (auto i, auto j); + +struct A { + A(int,int); +}; + +void +g (int a) +{ + A b1(auto(42), auto(42)); + A b2(auto(a), auto(42)); + A b3(auto(42), auto(a)); + A b4(auto(a), // { dg-error "13:'auto' parameter" } + auto(a2)); // { dg-error "13:'auto' parameter" } + int v1(auto(42)); + int fn1(auto(a)); // { dg-error "16:'auto' parameter" } +} base-commit: 767e2674875139ac8f354ceee655c1a9561b9779
