[llvm] Automatic removal of unused standard header (PR #192800)

[via llvm-commits]

serge-sans-paille wrote:

> Sorry if it's a stupid question - does the tool consider whether C/C++ library includes incidentally/indirectly are taking place?

It's not :-)

> In which case it might appear to be unused only because some other prior include pulled it in (for this particular C/C++ library implementation, for this particular version of it etc).

The algorithm of diskarzhañ is stupidly simple: each standard header is associated with the set of symbols it defines (e.g. `<vector>` only defines `std::vector`, although some implementation may bring in `<cstddef> for `std::size_t`). If a standard header is included but none of the symbol it defines is referenced in the same code, the include is removed.



https://github.com/llvm/llvm-project/pull/192800