[PATCH] D112646: [clang-tidy] Add `readability-container-contains` check

[Adrian Vogelsgesang via Phabricator via cfe-commits]

avogelsgesang created this revision.
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This commit introduces a new check `readability-container-contains`
which finds usages of `container.count()` which should be replaced
by a call to the `container.contains()` method introduced in C++ 20.

For containers which permit multiple entries per key (`multimap`,
`multiset`, ...), `contains` is more efficient than `count` because
`count` has to do unnecessary additional work.

While this this performance difference does not exist for containers
with only a single entry per key (`map`, `unordered_map`, ...),
`contains` still conveys the intent better.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D112646

Files:
  clang-tools-extra/clang-tidy/readability/CMakeLists.txt
  clang-tools-extra/clang-tidy/readability/ContainerContainsCheck.cpp
  clang-tools-extra/clang-tidy/readability/ContainerContainsCheck.h
  clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
  clang-tools-extra/docs/ReleaseNotes.rst
  clang-tools-extra/docs/clang-tidy/checks/list.rst
  clang-tools-extra/docs/clang-tidy/checks/readability-container-contains.rst
  clang-tools-extra/test/clang-tidy/checkers/readability-container-contains.cpp

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