[clang] 259eaa6 - [C++20] [Modules] Fix the duplicated static initializer problem (#114193)

[via cfe-commits]

Author: Chuanqi Xu
Date: 2024-10-30T17:27:04+08:00
New Revision: 259eaa6878ead1e2e7ef572a874dc3d885c1899b

URL: https://github.com/llvm/llvm-project/commit/259eaa6878ead1e2e7ef572a874dc3d885c1899b
DIFF: https://github.com/llvm/llvm-project/commit/259eaa6878ead1e2e7ef572a874dc3d885c1899b.diff

LOG: [C++20] [Modules] Fix the duplicated static initializer problem (#114193)

Reproducer:

```
//--- a.cppm
export module a;
int func();
static int a = func();

//--- a.cpp
import a;
```

The `func()` should only execute once. However, before this patch we
will somehow import `static int a` from a.cppm incorrectly and
initialize that again.

This is super bad and can introduce serious runtime behaviors.

And also surprisingly, it looks like the root cause of the problem is
simply some oversight choosing APIs.

Added: 
    clang/test/Modules/static-initializer.cppm

Modified: 
    clang/lib/CodeGen/CodeGenModule.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 2bcca5e85bdfeb..ba376f9ecfacde 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -7146,8 +7146,8 @@ void CodeGenModule::EmitTopLevelDecl(Decl *D) {
     // For C++ standard modules we are done - we will call the module
     // initializer for imported modules, and that will likewise call those for
     // any imports it has.
-    if (CXX20ModuleInits && Import->getImportedOwningModule() &&
-        !Import->getImportedOwningModule()->isModuleMapModule())
+    if (CXX20ModuleInits && Import->getImportedModule() &&
+        Import->getImportedModule()->isNamedModule())
       break;
 
     // For clang C++ module map modules the initializers for sub-modules are

diff  --git a/clang/test/Modules/static-initializer.cppm b/clang/test/Modules/static-initializer.cppm
new file mode 100644
index 00000000000000..10d4854ee67fa6
--- /dev/null
+++ b/clang/test/Modules/static-initializer.cppm
@@ -0,0 +1,18 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20 %t/a.cppm -emit-module-interface -o %t/a.pcm
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20 %t/a.cpp -fmodule-file=a=%t/a.pcm -emit-llvm -o - | FileCheck %t/a.cpp
+
+//--- a.cppm
+export module a;
+int func();
+static int a = func();
+
+//--- a.cpp
+import a;
+
+// CHECK-NOT: internal global
+// CHECK-NOT: __cxx_global_var_init
+