1 files changed, 27 insertions, 0 deletions
diff --git a/lang/swift510/files/patch-swift_lib_ClangImporter_ClangImporter.cpp b/lang/swift510/files/patch-swift_lib_ClangImporter_ClangImporter.cpp
new file mode 100644
index 000000000000..16353a0c788a
--- /dev/null
+++ b/lang/swift510/files/patch-swift_lib_ClangImporter_ClangImporter.cpp
@@ -0,0 +1,27 @@
+--- swift/lib/ClangImporter/ClangImporter.cpp.orig	2024-06-06 04:26:30 UTC
++++ swift/lib/ClangImporter/ClangImporter.cpp
+@@ -4143,9 +4143,22 @@ void ClangModuleUnit::getImportedModulesForLookup(
+   for (auto importMod : topLevelImported) {
+     auto wrapper = owner.getWrapperForModule(importMod);
+ 
+-    auto actualMod = wrapper->getOverlayModule();
+-    if (!actualMod || actualMod == topLevelOverlay)
++    ModuleDecl *actualMod = nullptr;
++    if (owner.SwiftContext.LangOpts.EnableCXXInterop && topLevel &&
++        isCxxStdModule(topLevel) && wrapper->clangModule &&
++        isCxxStdModule(wrapper->clangModule)) {
++      // The CxxStdlib overlay re-exports the clang module std, which in recent
++      // libc++ versions re-exports top-level modules for different std headers
++      // (std_string, std_vector, etc). The overlay module for each of the std
++      // modules is the CxxStdlib module itself. Make sure we return the actual
++      // clang modules (std_xyz) as transitive dependencies instead of just
++      // CxxStdlib itself.
+       actualMod = wrapper->getParentModule();
++    } else {
++      actualMod = wrapper->getOverlayModule();
++      if (!actualMod || actualMod == topLevelOverlay)
++        actualMod = wrapper->getParentModule();
++    }
+ 
+     assert(actualMod && "Missing imported overlay");
+     imports.push_back({ImportPath::Access(), actualMod});