[all-commits] [llvm/llvm-project] b9ca97: [clang-tidy] Add portability-std-allocator-const c...

[Fangrui Song via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b9ca972b1ff0548a831fe416cec8d39f7e569c94
      https://github.com/llvm/llvm-project/commit/b9ca972b1ff0548a831fe416cec8d39f7e569c94
  Author: Fangrui Song <i at maskray.me>
  Date:   2022-04-14 (Thu, 14 Apr 2022)

  Changed paths:
    M clang-tools-extra/clang-tidy/portability/CMakeLists.txt
    M clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
    A clang-tools-extra/clang-tidy/portability/StdAllocatorConstCheck.cpp
    A clang-tools-extra/clang-tidy/portability/StdAllocatorConstCheck.h
    M clang-tools-extra/docs/ReleaseNotes.rst
    M clang-tools-extra/docs/clang-tidy/checks/list.rst
    A clang-tools-extra/docs/clang-tidy/checks/portability-std-allocator-const.rst
    A clang-tools-extra/test/clang-tidy/checkers/portability-std-allocator-const.cpp

  Log Message:
  -----------
  [clang-tidy] Add portability-std-allocator-const check

Report use of `std::vector<const T>` (and similar containers of const
elements). These are now allowed in standard C++ due to undefined
`std::allocator<const T>`. They do not compile with libstdc++ or MSVC.
Future libc++ will remove the extension (D120996).
See docs/clang-tidy/checks/portability-std-allocator-const.rst for detail.

I have attempted clean-up in a large code base. Here are some statistics:

* 98% are related to the container `std::vector`, among `deque/forward_list/list/multiset/queue/set/stack/vector`.
* 24% are related to `std::vector<const std::string>`.
* Both `std::vector<const absl::string_view>` and `std::vector<const int>` contribute 2%. The other contributors spread over various class types.

The check can be useful to other large code bases and may serve as an example
for future libc++ strictness improvement.

Note: on MSVC where -fdelayed-template-parsing is the default, the check cannot
catch cases in uninstantiated templates.

Reviewed By: sammccall

Differential Revision: https://reviews.llvm.org/D123655