From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2122) id 6B6833857802; Wed, 2 Dec 2020 21:15:25 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6B6833857802 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Jason Merrill To: gcc-cvs@gcc.gnu.org Subject: [gcc r11-5682] c++: Give better placeholder diagnostic X-Act-Checkin: gcc X-Git-Author: Jason Merrill X-Git-Refname: refs/heads/master X-Git-Oldrev: d9288bd28e24c755a7216311ee5247e7c88270a6 X-Git-Newrev: 2847d7d28ea79e2f93049fad16f931b6705c9fff Message-Id: <20201202211525.6B6833857802@sourceware.org> Date: Wed, 2 Dec 2020 21:15:25 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 02 Dec 2020 21:15:25 -0000 https://gcc.gnu.org/g:2847d7d28ea79e2f93049fad16f931b6705c9fff commit r11-5682-g2847d7d28ea79e2f93049fad16f931b6705c9fff Author: Jason Merrill Date: Thu Nov 26 05:45:02 2020 -0500 c++: Give better placeholder diagnostic We were saying 'auto parameter not permitted' in a place where 'auto' is in fact permitted in C++20, but a class template placeholder is not. gcc/cp/ChangeLog: * decl.c (grokdeclarator): Improve diagnostic for disallowed CTAD placeholder. gcc/testsuite/ChangeLog: * g++.dg/other/pr88187.C: Adjust expected error. * g++.dg/cpp2a/class-deduction-abbrev1.C: New test. Diff: --- gcc/cp/decl.c | 10 ++++++++++ gcc/testsuite/g++.dg/cpp2a/class-deduction-abbrev1.C | 13 +++++++++++++ gcc/testsuite/g++.dg/other/pr88187.C | 2 +- 3 files changed, 24 insertions(+), 1 deletion(-) diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 1e2bae4afba..0cf84a0750c 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -13145,6 +13145,16 @@ grokdeclarator (const cp_declarator *declarator, if (decl_context == PARM && AUTO_IS_DECLTYPE (auto_node)) error_at (typespec_loc, "cannot declare a parameter with %"); + else if (tree c = CLASS_PLACEHOLDER_TEMPLATE (auto_node)) + { + auto_diagnostic_group g; + error_at (typespec_loc, + "class template placeholder %qE not permitted " + "in this context", c); + if (decl_context == PARM && cxx_dialect >= cxx20) + inform (typespec_loc, "use % for an " + "abbreviated function template"); + } else error_at (typespec_loc, "% parameter not permitted in this context"); diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-abbrev1.C b/gcc/testsuite/g++.dg/cpp2a/class-deduction-abbrev1.C new file mode 100644 index 00000000000..f9310090b5b --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-abbrev1.C @@ -0,0 +1,13 @@ + // { dg-do compile { target c++20 } } + +template struct A { }; +template concept is_A = requires { A(T()); }; + +void f(auto); // OK +void f(is_A auto); // OK +void f(A); // { dg-error "placeholder" } + +int main() +{ + f(A()); +} diff --git a/gcc/testsuite/g++.dg/other/pr88187.C b/gcc/testsuite/g++.dg/other/pr88187.C index ebdafddc634..13466d3ce57 100644 --- a/gcc/testsuite/g++.dg/other/pr88187.C +++ b/gcc/testsuite/g++.dg/other/pr88187.C @@ -4,4 +4,4 @@ template struct A; void f (A ()); // { dg-error "6:variable or field 'f' declared void" "" { target c++14_down } } // { dg-error "missing template arguments before '\\(' token" "" { target c++14_down } .-1 } - // { dg-error "'auto' parameter not permitted in this context" "" { target c++17 } .-2 } + // { dg-error "placeholder .A. not permitted in this context" "" { target c++17 } .-2 }