[clang][modules] Fix local submodule visibility of macros from transitive import (#122955)

When we mark a module visible, we normally mark all of its non-explicit
submodules and other exports as visible. However, when we first enter a
submodule we should not make them visible to the submodule itself until
they are actually imported. Marking exports visible before import would
cause bizarre behaviour with local submodule visibility, because it
happened before we discovered the submodule's transitive imports and
could fail to make them visible in the parent module depending on
whether the submodules involved were explicitly defined (module X) or
implicitly defined from an umbrella (module *).

rdar://136524433

clang/include/clang/Basic/Module.h

@@ -881,10 +881,11 @@ public:
                          StringRef Message)>;
 
   /// Make a specific module visible.
-  void setVisible(Module *M, SourceLocation Loc,
-                  VisibleCallback Vis = [](Module *) {},
-                  ConflictCallback Cb = [](ArrayRef<Module *>, Module *,
-                                           StringRef) {});
+  void setVisible(
+      Module *M, SourceLocation Loc, bool IncludeExports = true,
+      VisibleCallback Vis = [](Module *) {},
+      ConflictCallback Cb = [](ArrayRef<Module *>, Module *, StringRef) {});
+
 private:
   /// Import locations for each visible module. Indexed by the module's
   /// VisibilityID.

clang/include/clang/Lex/Preprocessor.h

@@ -1755,7 +1755,8 @@ public:
   bool LexAfterModuleImport(Token &Result);
   void CollectPpImportSuffix(SmallVectorImpl<Token> &Toks);
 
-  void makeModuleVisible(Module *M, SourceLocation Loc);
+  void makeModuleVisible(Module *M, SourceLocation Loc,
+                         bool IncludeExports = true);
 
   SourceLocation getModuleImportLoc(Module *M) const {
     return CurSubmoduleState->VisibleModules.getImportLoc(M);

clang/lib/Basic/Module.cpp

@@ -662,7 +662,8 @@ LLVM_DUMP_METHOD void Module::dump() const {
 }
 
 void VisibleModuleSet::setVisible(Module *M, SourceLocation Loc,
-                                  VisibleCallback Vis, ConflictCallback Cb) {
+                                  bool IncludeExports, VisibleCallback Vis,
+                                  ConflictCallback Cb) {
   // We can't import a global module fragment so the location can be invalid.
   assert((M->isGlobalModule() || Loc.isValid()) &&
          "setVisible expects a valid import location");
@@ -688,12 +689,14 @@ void VisibleModuleSet::setVisible(Module *M, SourceLocation Loc,
     Vis(V.M);
 
     // Make any exported modules visible.
-    SmallVector<Module *, 16> Exports;
-    V.M->getExportedModules(Exports);
-    for (Module *E : Exports) {
-      // Don't import non-importable modules.
-      if (!E->isUnimportable())
-        VisitModule({E, &V});
+    if (IncludeExports) {
+      SmallVector<Module *, 16> Exports;
+      V.M->getExportedModules(Exports);
+      for (Module *E : Exports) {
+        // Don't import non-importable modules.
+        if (!E->isUnimportable())
+          VisitModule({E, &V});
+      }
     }
 
     for (auto &C : V.M->Conflicts) {

clang/lib/Lex/PPLexerChange.cpp

@@ -754,9 +754,10 @@ void Preprocessor::EnterSubmodule(Module *M, SourceLocation ImportLoc,
   // Switch to this submodule as the current submodule.
   CurSubmoduleState = &State;
 
-  // This module is visible to itself.
+  // This module is visible to itself, but exports should not be made visible
+  // until they are imported.
   if (FirstTime)
-    makeModuleVisible(M, ImportLoc);
+    makeModuleVisible(M, ImportLoc, /*IncludeExports=*/false);
 }
 
 bool Preprocessor::needModuleMacros() const {

clang/lib/Lex/Preprocessor.cpp

@@ -1331,9 +1331,10 @@ bool Preprocessor::LexAfterModuleImport(Token &Result) {
   return true;
 }
 
-void Preprocessor::makeModuleVisible(Module *M, SourceLocation Loc) {
+void Preprocessor::makeModuleVisible(Module *M, SourceLocation Loc,
+                                     bool IncludeExports) {
   CurSubmoduleState->VisibleModules.setVisible(
-      M, Loc, [](Module *) {},
+      M, Loc, IncludeExports, [](Module *) {},
       [&](ArrayRef<Module *> Path, Module *Conflict, StringRef Message) {
         // FIXME: Include the path in the diagnostic.
         // FIXME: Include the import location for the conflicting module.

clang/test/Modules/local-submodule-visibility-transitive-import.c

@@ -0,0 +1,62 @@
+// Checks that macros from transitive imports work with local submodule
+// visibility. In the below test, previously a() and d() failed because
+// OTHER_MACRO1 and OTHER_MACRO3 were not visible at the use site.
+
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t \
+// RUN:   -fmodules-local-submodule-visibility -I%t %t/tu.c -verify
+
+//--- Other1.h
+#define OTHER_MACRO1(...)
+
+//--- Other2.h
+#define OTHER_MACRO2(...)
+
+//--- Other3.h
+#define OTHER_MACRO3(...)
+
+//--- module.modulemap
+module Other {
+  module O1 { header "Other1.h" }
+  module O2 { header "Other2.h" }
+  module O3 { header "Other3.h" }
+}
+
+//--- Top/A.h
+#include "Other1.h"
+#define MACRO_A OTHER_MACRO1(x, y)
+
+//--- Top/B.h
+#include "Other2.h"
+#define MACRO_B OTHER_MACRO2(x, y)
+
+//--- Top/C.h
+#include "D.h"
+
+//--- Top/D.h
+#include "Other3.h"
+#define MACRO_D OTHER_MACRO3(x, y)
+
+//--- Top/Top.h
+#include "A.h"
+#include "B.h"
+#include "C.h"
+
+void a() MACRO_A;
+void b() MACRO_B;
+void d() MACRO_D;
+
+//--- Top/module.modulemap
+module Top {
+  umbrella header "Top.h"
+  module A { header "A.h" export * }
+  module D { header "D.h" export * }
+  module * { export * }
+  export *
+  export Other.O3
+}
+
+//--- tu.c
+#include "Top/Top.h"
+// expected-no-diagnostics