| Issue |
161100
|
| Summary |
[clang] Inlined method creates separate thread_local variables in each C++ module
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
smilediver
|
The following program seems to instantiate separate `thread_local` variables for each C++ module. I'm not sure if this is a bug or expected behavior. If I remove `static` from `test()`, or remove either `inline` or `__attribute__((always_inline))` from `scope::scope()`, then only a single `thread_local` variable is instantiated.
```
clang --version
clang version 21.1.2
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: C:\Program Files\LLVM\bin
```
main.cppm
```cpp
module;
export module app;
import a;
import b;
import var;
extern "C++" int main() {
scope s;
a_test();
b_test();
return 0;
}
```
a.cppm
```cpp
module;
export module a;
import var;
export void a_test() {
scope s;
}
```
b.cppm
```cpp
module;
export module b;
import var;
export void b_test() {
scope s;
}
```
var.cppm
```cpp
module;
#include <cstdio>
export module var;
struct thread_var {
thread_var() {
printf("thread_var ctor\n");
}
};
static thread_var* test() {
printf("test\n");
thread_local thread_var v;
return &v;
}
export struct scope {
inline __attribute__((always_inline)) scope() {
printf("scope\n");
test();
}
};
```
CMakeLists.txt
```cmake
cmake_minimum_required(VERSION 4.0)
set(CMAKE_CXX_STANDARD 20)
set(CMAKE_C_COMPILER clang)
set(CMAKE_CXX_COMPILER clang++)
project(test)
add_executable(test)
target_sources(test
PUBLIC FILE_SET CXX_MODULES FILES
main.cppm
a.cppm
b.cppm
var.cppm
)
```
Expected output:
```
scope
test
thread_var ctor
scope
test
scope
test
```
Actual output:
```
scope
test
thread_var ctor
scope
test
thread_var ctor
scope
test
thread_var ctor
```
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