[PATCH] D120540: [Driver] Enable to use C++20 modules standalone by -fcxx-modules

Tue Mar 15 02:47:41 PDT 2022

ChuanqiXu added a comment.

In D120540#3381905 <https://reviews.llvm.org/D120540#3381905>, @jansvoboda11 wrote:

> I agree. My understanding is that `-fcxx-modules` enables Clang modules that don't interact with C++20 modules. @Bigcheese, any thoughts?

Oh, if it is true, then it is in a chaos really. I mean the language variables set in `-fcxx-modules` is `CPlusPlusModules`. And we uses `CPlusPlusModules ` as the induction variable for C++20 modules for a relative long time.

My observation is that:

- `CPlusPlusModules ` is true if we set `-std=c++20` before this patch.
- `Modules` is true if we set `-fmodules` or `-fcxx-modules`.
- What I get from the previous patch is that we hope a smooth change from clang modules to C++20 modules.

So my conclusion might be that the `-fcxx-modules` is connected to both `C++20 modules` and `Clang Modules`. Is this intended or not?

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D120540/new/

https://reviews.llvm.org/D120540