[clang-tools-extra] create new clang-tidy check to add namespaces to symbol references (PR #70621)

[via cfe-commits]

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+// RUN: %check_clang_tidy %s readability-use-explicit-namespaces %t
+
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daltairwalter wrote:

Are there tools or resources for this?  I locally have done a lot more testing, but it is very clear how to turn this into test cases.

https://github.com/llvm/llvm-project/pull/70621