[C++20] [Module] The combination of iostream and file with .cppm suffix would crash #51873
Description
| Bugzilla Link | 52531 |
| Version | trunk |
| OS | All |
| Reporter | LLVM Bugzilla Contributor |
| CC | @dwblaikie,@zygoloid |
Extended Description
I met an interesting bug which would happen only if iosstream and module file end with .cppm.
Here is the reproducer:
// Hello.cppm
module;
#include <iostream>
export module Hello;
export void SayHello()
{
std::cout << "Hello World.\n";
}
// main.cpp
import Hello;
int main() {
SayHello();
return 0;
}
And if I compile it as:
clang++ -std=c++20 --precompile Hello.cppm -o Hello.pcm
clang++ -std=c++20 -fprebuilt-module-path=. Hello.pcm main.cpp
And the generated executable would crash.
Interestingly, it wouldn't crash if we use std::printf instead of std::cout
// Hello.cppm
module;
#include <cstdio>
export module Hello;
export void SayHello()
{
std::printf("Hello World.\n");
}
// main.cpp
import Hello;
int main() {
SayHello();
return 0;
}Also, it wouldn't crash if the suffix is cpp instead of cppm. For example:
// Hello.cpp
module;
#include <iostream>
export module Hello;
export void SayHello()
{
std::cout << "Hello World.\n";
}
// main.cpp
import Hello;
int main() {
SayHello();
return 0;
}
Compile argument:
clang++ -std=c++20 -Xclang -emit-module-interface Hello.cpp -o Hello.pcm
clang++ -std=c++20 -fprebuilt-module-path=. say_hello.cpp main.cpp
I am not sure if this is a bug in compiler or in runtime. It is appreciate if someone could help to confirm this.