[PATCH] D99903: [Clang][Sema] better -Wcast-function-type diagnose for pointer parameters and parameters with cv-qualifiers

[Yuanfang Chen via Phabricator via cfe-commits]

ychen created this revision.
ychen added a reviewer: rsmith.
ychen requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

1. Skip diagnosing all pointer-like parameters.
2. Replace `Context.hasSameUnqualifiedType` with `Context.hasSimilarType`.
3. Add corresponding tests.




After some thoughts, I think we could add the following extension in the
future (probably under an additional flag such as `-Wcast-function-type=2)
 according to user feedbacks for the reasons: 1) users could use
`void(*)(void)` to explicitly override checks (for example:
https://trac.webkit.org/changeset/231565/webkit); 2) these checks could
hide real bugs that users may want to catch; 3) using `void(*)(void)`
makes following extension worthwhile only when a codebase uses these
patterns on a large scale which seems unlikely.

(GCC does not do the following)

- allow integer promotion (`void(int)` -> `void(char)`)

- allow arbitrary pointer-to-member conversion

- allow parameter counts mismatch

the use pattern is "passing an extra (unwanted) parameter to callbacks"
https://bugs.freedesktop.org/show_bug.cgi?id=107349#c0

Thoughts?


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D99903

Files:
  clang/lib/Sema/SemaCast.cpp
  clang/test/Sema/warn-cast-function-type.c
  clang/test/Sema/warn-cast-function-type.m
  clang/test/SemaCXX/warn-cast-function-type.cpp

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