[clang-tools-extra] [clang-tidy] Added Conflicting Global Accesses checker (PR #130421)

[Baranov Victor via cfe-commits]

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+.. title:: clang-tidy - bugprone-conflicting-global-accesses
+
+bugprone-conflicting-global-accesses
+====================================
+
+Finds conflicting accesses on global variables.
+
+Modifying twice or reading and modifying a memory location without a
+defined sequence of the operations is either undefined behavior or has
+unspecified order. This checker is similar to the -Wunsequenced clang warning,
+however it only looks at global variables and therefore can find conflicting
+actions recursively inside functions as well.
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vbvictor wrote:

I think you should not explicitly exclude cases that are covered by "-Wunsequenced". It's okay for check to have duplicate functionality with compiler flags. Moreover, for gcc there is "-Wsequence-point" and we don't know to what extent "-Wunsequenced" can find bugs, so It's better just to mention that functionality of this check may overlap with existing compiler flags such as "-Wunsequenced", "-Wsequence-point".

https://github.com/llvm/llvm-project/pull/130421