[libc++] Remove Clang-11 support.

[Mordante]

Summary

Since we no longer officially support Clang 11 remove the work-arounds
for this version.

[ldionne]

LGTM!

Just FYI, to make sure you've removed all instances of Clang-11 related Lit features from the test suite, you can use this:

<build>/bin/llvm-lit libcxx/test libcxxabi/test --show-used-features

It will print a list of all the Lit features we mention in the test suite, and you can make sure that we don't mention clang-11 anymore after your patch. I guess grepping can also do the job, but sometimes it can be difficult to sort through the output if we mention clang-11 for things that are not Lit features. Anyway, just thought I'd let you know about this tool we have :-).

[Mordante]

In D112727#3093829, @ldionne wrote:

LGTM!

Just FYI, to make sure you've removed all instances of Clang-11 related Lit features from the test suite, you can use this:

<build>/bin/llvm-lit libcxx/test libcxxabi/test --show-used-features

It will print a list of all the Lit features we mention in the test suite, and you can make sure that we don't mention clang-11 anymore after your patch. I guess grepping can also do the job, but sometimes it can be difficult to sort through the output if we mention clang-11 for things that are not Lit features. Anyway, just thought I'd let you know about this tool we have :-).

Thanks I wasn't aware of that tool! I just grepped for everything that remotely resembled clang 11 and the number of hits was very manageable :-)

[Mordante]

Rebase to trigger CI.

libcxx/include/type_traits

 template <class _Tp>
 inline constexpr bool is_array_v = is_array<_Tp>::value;
 #endif
 
 #endif // __has_keyword(__is_array)
 
 // is_pointer
 
-// Before Clang 11 / AppleClang 12.0.5, __is_pointer didn't work for Objective-C types.
+// Before AppleClang 12.0.5, __is_pointer didn't work for Objective-C types.
 #if __has_keyword(__is_pointer) &&                                             \
-    !(defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER < 1100) &&               \
     !(defined(_LIBCPP_APPLE_CLANG_VER) && _LIBCPP_APPLE_CLANG_VER < 1205)
 
 template<class _Tp>
 struct _LIBCPP_TEMPLATE_VIS is_pointer : _BoolConstant<__is_pointer(_Tp)> { };
 
 #if _LIBCPP_STD_VER > 14
 template <class _Tp>
 inline constexpr bool is_pointer_v = __is_pointer(_Tp);

libcxx/test/std/utilities/format/format.formatter/format.context/format.formatter.spec/formatter.const_char_array.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++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-no-concepts
 // UNSUPPORTED: libcpp-has-no-incomplete-format
-// UNSUPPORTED: clang-11
 // TODO FMT Evaluate gcc-11 status
 // UNSUPPORTED: gcc-11
 // UNSUPPORTED: apple-clang-12
 
 // <format>
 
 // [format.formatter.spec]:
 // Each header that declares the template `formatter` provides the following