[clang] [clang-tools-extra] [clang][AST][clang-tidy] Do not set a reduced traversal scope in ASTM… (PR #132725)

[Carlos Galvez via cfe-commits]

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@@ -94,8 +94,6 @@ Improvements to clang-tidy
 - :program:`clang-tidy` no longer processes declarations from system headers
   by default, greatly improving performance. This behavior is disabled if the
   `SystemHeaders` option is enabled.
-  Note: this may lead to false negatives; downstream users may need to adjust
-  their checks to preserve existing behavior.
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carlosgalvezp wrote:

> explicit SkipSystemHeaders flag

The problem I have with such a flag is that 1) users will not report issues, just silence them with the flag, therefore 2) people will rely on the flag, so it will need to live forever and 3) we won't be able to unit test all checks with and without the flag.



https://github.com/llvm/llvm-project/pull/132725