[clang] 5828692 - [C++20] [Modules] Make TheImplicitGlobalModuleFragment and TheExportedImplicitGlobalModuleFragment to be useable modules

[Chuanqi Xu via cfe-commits]

Author: Chuanqi Xu
Date: 2023-03-03T11:15:29+08:00
New Revision: 5828692f70bc5f92fad9ed21a1844044924680aa

URL: https://github.com/llvm/llvm-project/commit/5828692f70bc5f92fad9ed21a1844044924680aa
DIFF: https://github.com/llvm/llvm-project/commit/5828692f70bc5f92fad9ed21a1844044924680aa.diff

LOG: [C++20] [Modules] Make TheImplicitGlobalModuleFragment and TheExportedImplicitGlobalModuleFragment to be useable modules

The unexported language linkage become unvisible to the current module
unit after the previous commit bf52ead24ca4. This patch fixes the issue.

Added: 
    clang/test/Modules/use-extern-language-linkage.cppm

Modified: 
    clang/lib/Sema/SemaDeclCXX.cpp
    clang/lib/Sema/SemaLookup.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index ae8b8d62bcf3b..21c02b7ba4aa1 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -16388,7 +16388,8 @@ Decl *Sema::ActOnFinishLinkageSpecification(Scope *S,
   // LinkageSpec isn't in the module created by itself. So we don't
   // need to pop it.
   if (getLangOpts().CPlusPlusModules && getCurrentModule() &&
-      getCurrentModule()->isGlobalModule() && getCurrentModule()->Parent)
+      getCurrentModule()->isImplicitGlobalModule() &&
+      getCurrentModule()->Parent)
     PopImplicitGlobalModuleFragment();
 
   PopDeclContext();

diff  --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index aeeb49005ed1a..09a38571762d5 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -1579,7 +1579,8 @@ bool Sema::isUsableModule(const Module *M) {
   // [module.global.frag]p1:
   //   The global module fragment can be used to provide declarations that are
   //   attached to the global module and usable within the module unit.
-  if (M == TheGlobalModuleFragment ||
+  if (M == TheGlobalModuleFragment || M == TheImplicitGlobalModuleFragment ||
+      M == TheExportedImplicitGlobalModuleFragment ||
       // If M is the module we're parsing, it should be usable. This covers the
       // private module fragment. The private module fragment is usable only if
       // it is within the current module unit. And it must be the current

diff  --git a/clang/test/Modules/use-extern-language-linkage.cppm b/clang/test/Modules/use-extern-language-linkage.cppm
new file mode 100644
index 0000000000000..bfaa6297abba8
--- /dev/null
+++ b/clang/test/Modules/use-extern-language-linkage.cppm
@@ -0,0 +1,25 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 %t/a.cppm -fsyntax-only -verify
+
+//--- foo.h
+extern "C++" void c_func();
+
+//--- a.cppm
+// expected-no-diagnostics
+module;
+#include "foo.h"
+export module a;
+export extern "C++" void foo() {}
+extern "C++" void bar() {}
+export extern "C" void foo_c() {}
+extern "C" void bar_c() {}
+export void a() {
+    foo();
+    bar();
+    foo_c();
+    bar_c();
+    c_func();
+}