[PATCH] D151187: [doc] Add casting style preference to coding standards

Tue May 23 04:56:31 PDT 2023

barannikov88 added a comment.

In D151187#4363988 <https://reviews.llvm.org/D151187#4363988>, @jhenderson wrote:

> In D151187#4363915 <https://reviews.llvm.org/D151187#4363915>, @barannikov88 wrote:
>
>> What about function style casts? I personally find them acceptable in limited cases, such as "constructing" int64_t from unsigned.
>
> It's a fair question, and I don't have a good answer for this. Strictly, we should //probably// forbid them in new code on the basis that they are just as bad as C-style casts (they are explicitly defined to be identical), with regards to safety etc, but I also have used them in the past for the same "constructing" style like you find. Any suggestion on how we might codify the latter.

Maybe adopt this clang-tidy check? https://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines/pro-type-cstyle-cast.html
That is, allow C/functional-style cast when it is known to be safe (like unsigned -> int64_t or enum -> int), and prefer named casts otherwise.
The check also provides fix-its, which is nice.

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https://reviews.llvm.org/D151187