[PATCH] D75332: [clang-tidy] Add module for llvm-libc and restrict-system-libc-header-check.

[Fangrui Song via Phabricator via cfe-commits]

MaskRay added a comment.

> `RestrictSystemLibcHeadersCheck`

As I commented previously, I think the checker name should be generalized, as it does not need to be coupled with llvm-libc. Other projects may have similar needs. For example, they don't want to accidentally include a system zlib.h -> they may ship a bundled zlib (say, in third_party/zlib/).

Maybe `misc/` (or `portability/`) is more suitable?



================
Comment at: clang-tools-extra/clang-tidy/llvmlibc/RestrictSystemLibcHeadersCheck.cpp:49
+  if (SrcMgr::isSystem(FileType)) {
+    // Compiler provided headers are allowed (e.g stddef.h).
+    if (SearchPath == CompilerIncudeDir) {
----------------
This is actually an interesting topic.

On FreeBSD and linux-musl, stdalign.h stdarg.h stdbool.h stddef.h stdint.h stdnoreturn.h are provided by libc instead.

After D65699,

```
% clang -fsyntax-only -target x86_64-linux-musl -v /tmp/c/a.c
...
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include
 /usr/include/x86_64-linux-gnu
 /usr/include
 /tmp/ReleaseA/lib/clang/11.0.0/include
End of search list.
```

Note that the $resource_dir/include is after libc search directories on a Linux glibc (x86_64-linux-gnu) system.


Using a compiler intrinsic file (e.g. `x86intrin.h`) may be less controversial. It leaves to llvm-libc to decide which ordering is better. (I lean toward FreeBSD/linux musl way.)


================
Comment at: clang-tools-extra/clang-tidy/llvmlibc/RestrictSystemLibcHeadersCheck.cpp:52
+      return;
+    }
+    if (!SM.isInMainFile(HashLoc)) {
----------------
Drop excess parentheses.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D75332/new/

https://reviews.llvm.org/D75332