[PATCH] D155457: [clang] Skip tautological comparison if the comparison involves the 'size_t' type

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added a comment.

In D155457#4507107 <https://reviews.llvm.org/D155457#4507107>, @xgupta wrote:

> In D155457#4506405 <https://reviews.llvm.org/D155457#4506405>, @xbolva00 wrote:
>
>> You should add a testcase which uses “expected no diagnostics”.
>
> There is some issue writing test
>
>   $ cat type-limit-compare.cpp
>   // RUN: %clang_cc1  -fsyntax-only -Wtautological-type-limit-compare -verify %s
>   // expected-no-diagnostics
>   
>   #include <cstddef>
>   #include <cstdint>
>   #include <limits>
>   
>   bool foo(uint64_t Size) {
>     if (sizeof(std::size_t) < sizeof(uint64_t) &&
>        Size > static_cast<uint64_t>(std::numeric_limits<std::size_t>::max())) // no-warning
>       return false;
>     return true;
>   }
>
> failed with
>
>   $ llvm-project/clang/test/Sema/type-limit-compare.cpp:4:10: fatal error: 'cstddef' file not found
>       4 | #include <cstddef>
>         |          ^~~~~~~~~

We typically do not include any system headers (STL or otherwise) as part of the compiler tests; that would test whatever is found on the test system instead of a consistent test. Instead, I'd recommend doing:

  namespace std {
  using size_t = decltype(sizeof(0));
  }

Similarly, you can replace `uint64_t` with `unsigned long long` and the `numeric_limits` call with `__SIZE_MAX__`


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D155457/new/

https://reviews.llvm.org/D155457