[libc++] Narrow the exports for common_type

[ldionne]

Based on a comment in #99473, it seems like export * may be overkill.

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Louis Dionne (ldionne)

Changes

Based on a comment in #99473, it seems like export * may be overkill.

---

Full diff: https://github.com/llvm/llvm-project/pull/111681.diff

1 Files Affected:

• (modified) libcxx/include/module.modulemap (+3-3)

diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
index 22a1313498e73e..8c17945bad440b 100644
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -73,9 +73,9 @@ module std_core [system] {
     module common_reference                           { header "__type_traits/common_reference.h" }
     module common_type {
       header "__type_traits/common_type.h"
-      // We need to export everything from this module because common_type inherits from __builtin_common_type,
-      // which needs to be re-exported.
-      export *
+      // We need to export those because common_type expands to either of those based on __builtin_common_type.
+      export std_core.type_traits.type_identity
+      export std_core.utility_core.empty
     }
     module conditional                                { header "__type_traits/conditional.h" }
     module conjunction                                { header "__type_traits/conjunction.h" }

[philnik777]

LGTM assuming the CI is happy. I hope this is actually what's needed to make the modules build happy.