These are identified by misc-include-cleaner. I've filtered out those that break builds. Also, I'm staying away from llvm-config.h, config.h, and Compiler.h, which likely cause platform- or compiler-specific build failures.
Fix applied by running: run-clang-tidy.py -checks=-*,modernize-concat-nested-namespaces Differential Revision: https://reviews.llvm.org/D141770
Implements rule ES.75 of C++ Core Guidelines. Differential Revision: https://reviews.llvm.org/D132461