From 0801f419440c14f6772b28f763ad7d40f7f7a580 Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Fri, 15 May 2020 00:05:33 -0400 Subject: c++: Change the default dialect to C++17. Since GCC 9, C++17 support is no longer experimental. It was too late to change the default C++ dialect to C++17 in GCC 10, but I think now it's time to pull the trigger (C++14 was made the default in GCC 6.1). We're still missing two C++17 library features, but that shouldn't stop us. See and for the C++17 status. I won't list all C++17 features here, but just a few heads-up: - trigraphs were removed (hardly anyone cares, unless your keyboard is missing the # key), - operator++(bool) was removed (so some tests now run in C++14 and down only), - the keyword register was removed (some legacy code might trip on this), - noexcept specification is now part of the type system and C++17 does not allow dynamic exception specifications anymore (the empty throw specification is still available, but it is deprecated), - the evaluation order rules are different in C++17, - static constexpr data members are now implicitly inline (which makes them definitions), - C++17 requires guaranteed copy elision, meaning that a copy/move constructor call might be elided completely. That means that if something relied on a constructor being instantiated via e.g. copying a function parameter, it might now fail. I'll post an update for cxx-status.html and add a new caveat to changes.html once this is in. gcc/ChangeLog: * doc/invoke.texi (C Dialect Options): Adjust -std default for C++. * doc/standards.texi (C Language): Correct the default dialect. (C++ Language): Update the default for C++ to gnu++17. gcc/c-family/ChangeLog: * c-opts.c (c_common_init_options): Default to gnu++17. gcc/testsuite/ChangeLog: * c-c++-common/torture/vector-subscript-3.c: In C++17, define away the keyword register. * g++.dg/cpp1z/attributes-enum-1a.C: Only run pre-C++17. * g++.dg/cpp1z/fold7a.C: Likewise. * g++.dg/cpp1z/nontype3a.C: Likewise. * g++.dg/cpp1z/utf8-2a.C: Likewise. * g++.dg/parse/error11.C: Update expected diagnostics for C++17. * g++.dg/torture/pr34850.C: Add -Wno-attribute-warning. * g++.dg/torture/pr49394.C: In C++17, use noexcept(false). * g++.dg/torture/pr82154.C: Use -std=c++14. * lib/target-supports.exp: Set to C++17. * obj-c++.dg/try-catch-9.mm: Use -Wno-register. libgomp/ChangeLog: * testsuite/libgomp.c++/atomic-3.C: Use -std=gnu++14. --- libgomp/testsuite/libgomp.c++/atomic-3.C | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'libgomp') diff --git a/libgomp/testsuite/libgomp.c++/atomic-3.C b/libgomp/testsuite/libgomp.c++/atomic-3.C index f957b2f..c02532d 100644 --- a/libgomp/testsuite/libgomp.c++/atomic-3.C +++ b/libgomp/testsuite/libgomp.c++/atomic-3.C @@ -1,5 +1,6 @@ // { dg-do run } -// { dg-options "-Wno-deprecated" } +// C++17 forbids ++ on bool. +// { dg-options "-Wno-deprecated -std=gnu++14" } extern "C" void abort (void); bool v, x1, x2, x3, x4, x5, x6; -- cgit v1.1