[PATCH] D106394: [clang][pp] adds '#pragma include_instead'

[Christopher Di Bella via Phabricator via cfe-commits]

cjdb added a comment.

In D106394#2905660 <https://reviews.llvm.org/D106394#2905660>, @dblaikie wrote:

> Just a thought (nothing to hold up this patch/suggest a revert/suggest any immediate action), but:
>
>> The problem with extending this to non-system headers is that you need a way to tell which headers are allowed to include the detail headers and which ones are not.
>
> What if the analysis was done on the entire #include path from the current primary source file - rather than from the immediate include location? Then the requirement could be "This header must be directly or indirectly included from one of the headers listed in include_instead, otherwise there will be a warning" - could that generalize to other use cases/not only system headers?

I think this would mean that something like libc++'s `<__ranges/concepts.h>` couldn't directly include `<__iterator/concepts.h>`? Also, how does this play with `#pragma GCC system_header` detection?


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  https://reviews.llvm.org/D106394/new/

https://reviews.llvm.org/D106394