From e7f0873a9c4ebccd078fc5330866efe0cd4c1309 Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Wed, 8 Jul 2020 19:45:34 -0400 Subject: [PATCH] c++: Diagnose cv-qualified decltype(auto) [PR79815] "If the placeholder is the decltype(auto) type-specifier, T shall be the placeholder alone." but we weren't detecting "const decltype(auto)". I've just expanded the existing diagnostic detecting "decltype(auto) &" and similar. gcc/cp/ChangeLog: PR c++/79815 * decl.c (grokdeclarator): Detect cv-qual decltype(auto). * pt.c (do_auto_deduction): Likewise. gcc/testsuite/ChangeLog: PR c++/79815 * g++.dg/cpp1y/auto-fn59.C: New test. --- gcc/cp/decl.c | 17 +++++++++++++---- gcc/cp/pt.c | 6 ++++++ gcc/testsuite/g++.dg/cpp1y/auto-fn59.C | 8 ++++++++ 3 files changed, 27 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp1y/auto-fn59.C diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 6e4d546d55e..db91b50a4f0 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -12250,11 +12250,20 @@ grokdeclarator (const cp_declarator *declarator, /* Only plain decltype(auto) is allowed. */ if (tree a = type_uses_auto (type)) { - if (AUTO_IS_DECLTYPE (a) && a != type) + if (AUTO_IS_DECLTYPE (a)) { - error_at (typespec_loc, "%qT as type rather than " - "plain %", type); - return error_mark_node; + if (a != type) + { + error_at (typespec_loc, "%qT as type rather than " + "plain %", type); + return error_mark_node; + } + else if (TYPE_QUALS (type) != TYPE_UNQUALIFIED) + { + error_at (typespec_loc, "% cannot be " + "cv-qualified"); + return error_mark_node; + } } } diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index 4e1c77a6bd7..defc2a9abd8 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -28993,6 +28993,12 @@ do_auto_deduction (tree type, tree init, tree auto_node, error ("%qT as type rather than plain %", type); return error_mark_node; } + else if (TYPE_QUALS (type) != TYPE_UNQUALIFIED) + { + if (complain & tf_error) + error ("% cannot be cv-qualified"); + return error_mark_node; + } } else { diff --git a/gcc/testsuite/g++.dg/cpp1y/auto-fn59.C b/gcc/testsuite/g++.dg/cpp1y/auto-fn59.C new file mode 100644 index 00000000000..8f6ec9b79ab --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/auto-fn59.C @@ -0,0 +1,8 @@ +// PR c++/79815 +// { dg-do compile { target c++14 } } + +decltype(auto) const x = 1; // { dg-error "cannot be cv-qualified" } +volatile decltype(auto) x2 = 1; // { dg-error "cannot be cv-qualified" } +const volatile decltype(auto) x3 = 1; // { dg-error "cannot be cv-qualified" } +const decltype(auto) fn() { return 42; } // { dg-error "cannot be cv-qualified" } +const decltype(auto) fn2(); // { dg-error "cannot be cv-qualified" } -- 2.30.2