-gmodules: Emit debug info for implicit module imports via #include.

When a type is only used as a template parameter and that type is the
only type imported from another #include'd module, no skeleton CU for
that module is generated, so a consumer doesn't know where to find the
type definition. By emitting an import declaration, we can force a
skeleton CU to be generated for each imported module.

rdar://problem/36266156

llvm-svn: 321754

1 files changed, 5 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp b/clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp
index cb695e7..150b64f 100644
--- a/clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp
+++ b/clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp
@@ -228,6 +228,11 @@ public:
       Builder->getModuleDebugInfo()->completeRequiredType(RD);
   }
 
+  void HandleImplicitImportDecl(ImportDecl *D) override {
+    if (!D->getImportedOwningModule())
+      Builder->getModuleDebugInfo()->EmitImportDecl(*D);
+  }
+
   /// Emit a container holding the serialized AST.
   void HandleTranslationUnit(ASTContext &Ctx) override {
     assert(M && VMContext && Builder);