[libc++] Promote GCC 11 to mandatory CI

[ldionne]

Summary

Also, fix the last issue that prevented GCC 11 from passing the test
suite. Thanks to everyone else who fixed issues.

[• Quuxplusone]

libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_is_lock_free.pass.cpp

30–32

Whatever change is made to t probably also needs to be made to vt.
D103769 is vaguely related.

libcxx/utils/ci/Dockerfile

61

I'd leave this comment as "a recent GCC", since otherwise it'll be lying in a few months from now.

libcxx/utils/ci/buildkite-pipeline.yml

138–149

Would it be an unconscionable waste of buildkite resources to just leave this here, and update the gcc-next target to GCC 12 when it's released? As with the comment above, it seems silly to be churning this stuff around twice per GCC-release-cycle, when we could get away with updating it just once per GCC-release-cycle.

[ldionne]

Update XFAIL for libc++abi on recent GCC

[ldionne]

Address review comments and clarify intent about supported versions.

libcxx/utils/ci/Dockerfile

61

Actually, I think it's important to document the intent here. See my next update, hopefully it makes it clearer what we're trying to do.

[• Quuxplusone]

libcxx/utils/ci/Dockerfile

61

OK, I buy this new phrasing. LGTM.

[mizvekov]

libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_is_lock_free.pass.cpp

30

This initialization and the similar one below would not work from C++14 and below.
std::atomic is not copy construtible, and only starting from C++17 this initialization here from a prvalue of the same type performs direct initialization, and not a copy.

[ldionne]

libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_is_lock_free.pass.cpp

30

Just circling back -- we solved this in our discussion on Discord, and I'm fixing it in D105936.

libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_is_lock_free.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: libcpp-has-no-threads
 // XFAIL: !is-lockfree-runtime-function
 
 // <atomic>
 
 // template <class T>
-//     bool
-//     atomic_is_lock_free(const volatile atomic<T>* obj);
+// bool atomic_is_lock_free(const volatile atomic<T>* obj);
 //
 // template <class T>
-//     bool
-//     atomic_is_lock_free(const atomic<T>* obj);
+// bool atomic_is_lock_free(const atomic<T>* obj);
 
 #include <atomic>
 #include <cassert>
 
 #include "test_macros.h"
 #include "atomic_helpers.h"
 
 template <class T>
 struct TestFn {
   void operator()() const {
     typedef std::atomic<T> A;
-    A t;
+    A t = T();
     bool b1 = std::atomic_is_lock_free(static_cast<const A*>(&t));
-    volatile A vt;
+    volatile A vt = T();
     bool b2 = std::atomic_is_lock_free(static_cast<const volatile A*>(&vt));
     assert(b1 == b2);
   }
 };
 
-struct A
-{
-    char _[4];
+struct A {
+  char x[4];
 };
 
-int main(int, char**)
-{
-    TestFn<A>()();
-    TestEachAtomicType<TestFn>()();
-
+int main(int, char**) {
   return 0;
 }

libcxx/utils/ci/Dockerfile

 RUN . /tmp/env.sh && ln -s /usr/bin/clang++-${LLVM_TOT_VERSION} /usr/bin/clang++-tot && [ -e $(readlink /usr/bin/clang++-tot) ]
 RUN . /tmp/env.sh && ln -s /usr/bin/clang-${LLVM_TOT_VERSION} /usr/bin/clang-tot && [ -e $(readlink /usr/bin/clang-tot) ]
 
 # Install clang-format
 RUN . /tmp/env.sh && apt-get install -y clang-format-$LLVM_VERSION
 RUN ln -s $(find /usr/bin -regex '^.+/clang-format-[0-9.]+$') /usr/bin/clang-format && [ -e $(readlink /usr/bin/clang-format) ]
 RUN ln -s $(find /usr/bin -regex '^.+/git-clang-format-[0-9.]+$') /usr/bin/git-clang-format && [ -e $(readlink /usr/bin/git-clang-format) ]
 
-# Install a recent GCC
+# Install the most recent GCC version and the previous one (which are the two we support)
 RUN add-apt-repository ppa:ubuntu-toolchain-r/test
 RUN apt-get update && apt install -y gcc-10 g++-10 gcc-11 g++-11
-RUN ln -f -s /usr/bin/g++-10 /usr/bin/g++ && [ -e $(readlink /usr/bin/g++) ]
-RUN ln -f -s /usr/bin/gcc-10 /usr/bin/gcc && [ -e $(readlink /usr/bin/gcc) ]
 
 # Install a recent CMake
 RUN wget https://github.com/Kitware/CMake/releases/download/v3.18.2/cmake-3.18.2-Linux-x86_64.sh -O /tmp/install-cmake.sh
 RUN bash /tmp/install-cmake.sh --prefix=/usr --exclude-subdir --skip-license
 RUN rm /tmp/install-cmake.sh
 
 # Change the user to a non-root user, since some of the libc++ tests
 # (e.g. filesystem) require running as non-root. Also setup passwordless sudo.

libcxx/utils/ci/buildkite-pipeline.yml

artifact_paths:
       - "**/*.abilist"
     agents:
       queue: "libcxx-builders"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
           limit: 2
 
-  - label: "GCC/C++20"
+  - label: "GCC Current/C++20"
     command: "libcxx/utils/ci/run-buildbot generic-gcc"
     artifact_paths:
       - "**/test-results.xml"
     agents:
       queue: "libcxx-builders"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
           limit: 2
 
-  - label: "GCC-next/C++20"
-    command: "libcxx/utils/ci/run-buildbot generic-gcc-next"
+  #
+  # All other supported configurations of libc++.
+  #
+  - wait
+
+  - label: "GCC Previous/C++20"
+    command: "libcxx/utils/ci/run-buildbot generic-gcc-prev"
     artifact_paths:
       - "**/test-results.xml"
     agents:
       queue: "libcxx-builders"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
           limit: 2
-    soft_fail:
-      - exit_status: 1
-
-  #
-  # All other supported configurations of libc++.
-  #
-  - wait
 
   - label: "-fno-exceptions"
     command: "libcxx/utils/ci/run-buildbot generic-noexceptions"
     artifact_paths:
       - "**/test-results.xml"
     agents:
       queue: "libcxx-builders"
     retry:

libcxx/utils/ci/run-buildbot

 generic-32bit)
     export CC=clang
     export CXX=clang++
     clean
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-32bits.cmake"
     check-cxx-cxxabi
 ;;
 generic-gcc)
-    export CC=gcc
-    export CXX=g++
+    export CC=gcc-11
+    export CXX=g++-11
     clean
     generate-cmake
     check-cxx-cxxabi
 ;;
-generic-gcc-next)
-    export CC=gcc-11
-    export CXX=g++-11
+generic-gcc-prev)
+    export CC=gcc-10
+    export CXX=g++-10
     clean
     generate-cmake
     check-cxx-cxxabi
 ;;
 generic-asan)
     export CC=clang
     export CXX=clang++
     clean

libcxxabi/test/catch_member_function_pointer_02.pass.cpp

 //===--------------- catch_member_function_pointer_02.cpp -----------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // Can a noexcept member function pointer be caught by a non-noexcept catch
 // clause?
 // UNSUPPORTED: no-exceptions, libcxxabi-no-noexcept-function-type
 
 // GCC 7 and 8 support noexcept function types but this test still fails.
 // This is likely a bug in their implementation. Investigation needed.
-// XFAIL: gcc-7, gcc-8, gcc-9, gcc-10
+// XFAIL: gcc-7, gcc-8, gcc-9, gcc-10, gcc-11
 
 #include <cassert>
 
 struct X {
   template<bool Noexcept> void f() noexcept(Noexcept) {}
 };
 template<bool Noexcept> using FnType = void (X::*)() noexcept(Noexcept);