[clang] 3504937 - [C++20] [Modules] Don't create multiple global module fragment

[Chuanqi Xu via cfe-commits]

Author: Chuanqi Xu
Date: 2022-02-08T11:52:09+08:00
New Revision: 3504937dfb2b7d90b2c3b3c7b28c472d31489007

URL: https://github.com/llvm/llvm-project/commit/3504937dfb2b7d90b2c3b3c7b28c472d31489007
DIFF: https://github.com/llvm/llvm-project/commit/3504937dfb2b7d90b2c3b3c7b28c472d31489007.diff

LOG: [C++20] [Modules] Don't create multiple global module fragment

Since the serialization code would recognize modules by names and the
name of all global module fragment is <global>, so that the
serialization code would complain for the same module.

This patch fixes this by using a unique global module fragment in Sema.
Before this patch, the compiler would fail on an assertion complaining
the duplicated modules.

Reviewed By: urnathan, rsmith

Differential Revision: https://reviews.llvm.org/D115610

Added: 
    clang/test/CXX/module/module.unit/p7/Inputs/h8.h
    clang/test/CXX/module/module.unit/p7/Inputs/m8.cppm
    clang/test/CXX/module/module.unit/p7/t8.cpp

Modified: 
    clang/include/clang/Sema/Sema.h
    clang/lib/Sema/SemaModule.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 4b609f4b1477c..30148659562ed 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -2218,6 +2218,8 @@ class Sema final {
   };
   /// The modules we're currently parsing.
   llvm::SmallVector<ModuleScope, 16> ModuleScopes;
+  /// The global module fragment of the current translation unit.
+  clang::Module *GlobalModuleFragment = nullptr;
 
   /// Namespace definitions that we will export when they finish.
   llvm::SmallPtrSet<const NamespaceDecl*, 8> DeferredExportedNamespaces;

diff  --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp
index 747734f2d0ff0..85e58640044dc 100644
--- a/clang/lib/Sema/SemaModule.cpp
+++ b/clang/lib/Sema/SemaModule.cpp
@@ -720,19 +720,24 @@ Decl *Sema::ActOnFinishExportDecl(Scope *S, Decl *D, SourceLocation RBraceLoc) {
 
 Module *Sema::PushGlobalModuleFragment(SourceLocation BeginLoc,
                                        bool IsImplicit) {
-  ModuleMap &Map = PP.getHeaderSearchInfo().getModuleMap();
-  Module *GlobalModule =
-      Map.createGlobalModuleFragmentForModuleUnit(BeginLoc, getCurrentModule());
-  assert(GlobalModule && "module creation should not fail");
+  // We shouldn't create new global module fragment if there is already
+  // one.
+  if (!GlobalModuleFragment) {
+    ModuleMap &Map = PP.getHeaderSearchInfo().getModuleMap();
+    GlobalModuleFragment = Map.createGlobalModuleFragmentForModuleUnit(
+        BeginLoc, getCurrentModule());
+  }
+
+  assert(GlobalModuleFragment && "module creation should not fail");
 
   // Enter the scope of the global module.
-  ModuleScopes.push_back({BeginLoc, GlobalModule,
+  ModuleScopes.push_back({BeginLoc, GlobalModuleFragment,
                           /*ModuleInterface=*/false,
                           /*ImplicitGlobalModuleFragment=*/IsImplicit,
-                          /*VisibleModuleSet*/{}});
-  VisibleModules.setVisible(GlobalModule, BeginLoc);
+                          /*VisibleModuleSet*/ {}});
+  VisibleModules.setVisible(GlobalModuleFragment, BeginLoc);
 
-  return GlobalModule;
+  return GlobalModuleFragment;
 }
 
 void Sema::PopGlobalModuleFragment() {

diff  --git a/clang/test/CXX/module/module.unit/p7/Inputs/h8.h b/clang/test/CXX/module/module.unit/p7/Inputs/h8.h
new file mode 100644
index 0000000000000..2ef06cdc4054b
--- /dev/null
+++ b/clang/test/CXX/module/module.unit/p7/Inputs/h8.h
@@ -0,0 +1,4 @@
+#ifndef H8
+#define H8
+void foo();
+#endif

diff  --git a/clang/test/CXX/module/module.unit/p7/Inputs/m8.cppm b/clang/test/CXX/module/module.unit/p7/Inputs/m8.cppm
new file mode 100644
index 0000000000000..ef0c6c63462c1
--- /dev/null
+++ b/clang/test/CXX/module/module.unit/p7/Inputs/m8.cppm
@@ -0,0 +1,7 @@
+module;
+#include "h8.h"
+export module m8;
+
+extern "C++" {
+void bar();
+}

diff  --git a/clang/test/CXX/module/module.unit/p7/t8.cpp b/clang/test/CXX/module/module.unit/p7/t8.cpp
new file mode 100644
index 0000000000000..8310fc759f839
--- /dev/null
+++ b/clang/test/CXX/module/module.unit/p7/t8.cpp
@@ -0,0 +1,7 @@
+// RUN: rm -fr %t
+// RUN: mkdir %t
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %S/Inputs/m8.cppm -I%S/Inputs -o %t/m8.pcm
+// RUN: %clang_cc1 -std=c++20 -I%S/Inputs/ -fprebuilt-module-path=%t %s -verify -fsyntax-only
+// expected-no-diagnostics
+export module t8;
+import m8;