[libc++] Bump Clang support for Clang 4

[ldionne]

Summary

It's hard to imagine someone using a recent version of libc++ with a
roughly 3 years old Clang. Since we're not testing libc++ with Clang 3.5
anyway, claiming support for it is somewhat of a lie.

Note that we don't test Clang 4 either, however I have no reason to bump
the requirement beyond Clang 4 at the moment, whereas removing Clang 3.5
allows simplifying the test suite.

[EricWF]

LGTM.

I would like us to be even more aggressive bumping our compiler support,
but that's a conversation for another time.

[ldionne]

In D76618#1937113, @EricWF wrote:

LGTM.

I would like us to be even more aggressive bumping our compiler support,
but that's a conversation for another time.

Me too, since I think the benefit users are getting for us supporting old compilers is probably much smaller than we think. Few people upgrade their stdlib without upgrading their compiler. Let's take it one step at a time for now.

libcxx/docs/index.rst

 ============ ==================== ============ ========================
 macOS        i386, x86_64         Clang, GCC   libc++abi
 FreeBSD 10+  i386, x86_64, ARM    Clang, GCC   libcxxrt, libc++abi
 Linux        i386, x86_64         Clang, GCC   libc++abi
 ============ ==================== ============ ========================
 
 The following minimum compiler versions are strongly recommended.
 
-* Clang 3.5 and above
+* Clang 4.0 and above
 * GCC 5.0 and above.
 
 The C++03 dialect is only supported for Clang compilers.
 
 C++ Dialect Support
 ---------------------
 
 * C++11 - Complete

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t.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: c++98, c++03, c++11, c++14
 
 // asan and msan will not call the new handler.
 // UNSUPPORTED: sanitizer-new-delete
 
-// FIXME change this to XFAIL.
-// UNSUPPORTED: no-aligned-allocation && !gcc
-
 // Aligned allocation was not provided before macosx10.14 and as a result we
 // get availability errors when the deployment target is older than macosx10.14.
 // However, AppleClang 10 (and older) don't trigger availability errors, and
 // Clang < 8.0 doesn't warn for 10.13.
 // XFAIL: !(apple-clang-9 || apple-clang-10 || clang-7) && availability=macosx10.13
 // XFAIL: !(apple-clang-9 || apple-clang-10) && availability=macosx10.12
 // XFAIL: !(apple-clang-9 || apple-clang-10) && availability=macosx10.11
 // XFAIL: !(apple-clang-9 || apple-clang-10) && availability=macosx10.10

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_nothrow.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: c++98, c++03, c++11, c++14
 
 // asan and msan will not call the new handler.
 // UNSUPPORTED: sanitizer-new-delete
 
-// FIXME turn this into an XFAIL
-// UNSUPPORTED: no-aligned-allocation && !gcc
-
 // Aligned allocation was not provided before macosx10.14 and as a result we
 // get availability errors when the deployment target is older than macosx10.14.
 // However, AppleClang 10 (and older) don't trigger availability errors, and
 // Clang < 8.0 doesn't warn for 10.13.
 // XFAIL: !(apple-clang-9 || apple-clang-10 || clang-7) && availability=macosx10.13
 // XFAIL: !(apple-clang-9 || apple-clang-10) && availability=macosx10.12
 // XFAIL: !(apple-clang-9 || apple-clang-10) && availability=macosx10.11
 // XFAIL: !(apple-clang-9 || apple-clang-10) && availability=macosx10.10

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_nothrow_replace.pass.cpp

 // not export the aligned allocation functions.
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.12
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.11
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.10
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.9
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.8
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.7
 
-// XFAIL: no-aligned-allocation && !gcc
-
 // On Windows libc++ doesn't provide its own definitions for new/delete
 // but instead depends on the ones in VCRuntime. However VCRuntime does not
 // yet provide aligned new/delete definitions so this test fails.
 // XFAIL: LIBCXX-WINDOWS-FIXME
 
 // test operator new nothrow by replacing only operator new
 
 #include <new>

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_replace.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: c++98, c++03, c++11, c++14
 // UNSUPPORTED: sanitizer-new-delete
 
-// NOTE: GCC doesn't provide the -faligned-allocation flag to test for
-// XFAIL: no-aligned-allocation && !gcc
-
 // test operator new replacement
 
 #include <new>
 #include <cstddef>
 #include <cstdlib>
 #include <cstdint>
 #include <cassert>
 #include <limits>

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t.pass.cpp

 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.10
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.9
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.8
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.7
 
 // asan and msan will not call the new handler.
 // UNSUPPORTED: sanitizer-new-delete
 
-// FIXME turn this into an XFAIL
-// UNSUPPORTED: no-aligned-allocation && !gcc
-
 // On Windows libc++ doesn't provide its own definitions for new/delete
 // but instead depends on the ones in VCRuntime. However VCRuntime does not
 // yet provide aligned new/delete definitions so this test fails to compile/link.
 // XFAIL: LIBCXX-WINDOWS-FIXME
 
 // test operator new
 
 #include <new>

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_nothrow.pass.cpp

 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.10
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.9
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.8
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.7
 
 // asan and msan will not call the new handler.
 // UNSUPPORTED: sanitizer-new-delete
 
-// FIXME turn this into an XFAIL
-// UNSUPPORTED: no-aligned-allocation && !gcc
-
 // On Windows libc++ doesn't provide its own definitions for new/delete
 // but instead depends on the ones in VCRuntime. However VCRuntime does not
 // yet provide aligned new/delete definitions so this test fails to compile/link.
 // XFAIL: LIBCXX-WINDOWS-FIXME
 
 // test operator new (nothrow)
 
 #include <new>

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_nothrow_replace.pass.cpp

 // not export the aligned allocation functions.
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.12
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.11
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.10
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.9
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.8
 // XFAIL: (apple-clang-9 || apple-clang-10) && with_system_cxx_lib=macosx10.7
 
-// NOTE: gcc doesn't provide -faligned-allocation flag to test for
-// XFAIL: no-aligned-allocation && !gcc
-
 // On Windows libc++ doesn't provide its own definitions for new/delete
 // but instead depends on the ones in VCRuntime. However VCRuntime does not
 // yet provide aligned new/delete definitions so this test fails.
 // XFAIL: LIBCXX-WINDOWS-FIXME
 
 // test operator new nothrow by replacing only operator new
 
 #include <new>

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_replace.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: c++98, c++03, c++11, c++14
 // UNSUPPORTED: sanitizer-new-delete
 
-// NOTE: GCC doesn't provide a -faligned-allocation flag
-// XFAIL: no-aligned-allocation && !gcc
-
 // test operator new replacement
 
 #include <new>
 #include <cstddef>
 #include <cstdlib>
 #include <cstdint>
 #include <cassert>
 #include <limits>

libcxx/utils/libcxx/test/config.py

def configure_features(self):
 
         # Run a compile test for the -fsized-deallocation flag. This is needed
         # in test/std/language.support/support.dynamic/new.delete
         if self.cxx.hasCompileFlag('-fsized-deallocation'):
             self.config.available_features.add('-fsized-deallocation')
 
         if self.cxx.hasCompileFlag('-faligned-allocation'):
             self.config.available_features.add('-faligned-allocation')
-        else:
-            # FIXME remove this once more than just clang-4.0 support
-            # C++17 aligned allocation.
-            self.config.available_features.add('no-aligned-allocation')
 
         if self.cxx.hasCompileFlag('-fdelayed-template-parsing'):
             self.config.available_features.add('fdelayed-template-parsing')
 
         if self.get_lit_bool('has_libatomic', False):
             self.config.available_features.add('libatomic')
 
         macros = self._dump_macros_verbose()