[libcxx-commits] [PATCH] D156177: [libc++][Modules] Recreate the top level `std` clang module

[Mark de Wever via Phabricator via libcxx-commits]

Mordante added a comment.

In D156177#4533653 <https://reviews.llvm.org/D156177#4533653>, @Bigcheese wrote:

> Changing the name of a module (clang or C++20) is a breaking change, we need to keep importing `std` by name working with Clang modules.
>
> The Clang module `std` and the C++20 module `std` are different things in that the Clang module includes macros and the full content reachable from the top level headers, while the C++ 20 module does not include macros, and only guarantees a set list of names are visible.

I'm aware they are different. It's just not great to have two different things called the `std` module. But well that ship has sailed for a while. I was just not aware we use that name in the modular build. I've used the modular build in the past, but only imported single headers and not `std`.

In D156177#4533729 <https://reviews.llvm.org/D156177#4533729>, @aprantl wrote:

> In any case, it would be awesome if we could get the bots running again soon...!

Agreed. But since we need to backport this patch to LLVM 17 I want to make sure we have a proper patch.

I understand it's not great to have the LLDB build broken. It would be really great if the LLDB team could help libc++ to get LLDB working in the libc++ pre-commit CI to prevent breakage. Both @ldionne and I have reached out in the past to get assistance, but that did not result in a working LLDB in the CI. I don't recall the exact issues I ran into last time I tried, which I think is over a year ago.
We already have a job that bootstraps Clang and uses that Clang to test libc++ patches. It would be great to add LLDB to that job.



================
Comment at: libcxx/include/__std:159
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
----------------
Please move this on top.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D156177/new/

https://reviews.llvm.org/D156177