[libc-commits] [libc] [libc] Add missing casts in StrtolTest (PR #119054)

[Nick Desaulniers via libc-commits]

nickdesaulniers wrote:

> I'm not sure which warning switch we're using enables that.

LLVM has a neat utility called `diagtool` that can be used to quickly discover whether a particular `clang` diagnostic command line flag is part of another diagnostic "group." (Every time you add a new `clang` diagnostic command line flag, an existing "change detector" test trips; it detects changes by having a golden reference for the output of `diagtool tree`.

In this case, the group hierarchy for `-Wimplicit-int-conversion` looks like:

```
-Wnon-gcc
...
  -Wconversion
...
    -Wimplicit-int-conversion
```
(so `-Wimplicit-int-conversion` can either be enable explicitly via ` -Wimplicit-int-conversion`, or implicitly via `-Wconversion` or `-Wnon-gcc`. Of note: it's not part of `-Wall` or `-Wextra`).

It's probably worthwhile for us to set at least ` -Wimplicit-int-conversion` upstream in our cmake. `-Wconversion` itself is a large group, and might be quite noisy.

https://github.com/llvm/llvm-project/pull/119054