[clang] [Modules] No transitive source location change (PR #86912)

[Simon Tatham via cfe-commits]

statham-arm wrote:

> Let's see if @statham-arm (who introduced the `SourceLocation::[U]IntTy` typedefs) wants to weight in here.

I'm afraid my knowledge of C++ modules is very close to zero. They were mentioned in a training course I did last year, but not in much detail.

On 64-bit SourceLocation in general: our patch series to implement those as an option in clang was never fully landed, because the second half of it stalled in review. I'd still like to see it finished off, though I'm sure it would need some vigorous rebasing and retesting by now. The 32-bit SourceLocation limit is a problem for at least some of our users, apparently because there's a library of header files that break the limit all by themselves. (I'm not sure how; I haven't seen them. Maybe by including each other multiple times with different `#define`s?)

But I have no idea whether the same considerations would apply to modules, because I don't really know enough about modules, sorry!

https://github.com/llvm/llvm-project/pull/86912