Closed
Description
Clang will trigger a compilation error with:
- (A) a simple module interface with a template function calling a function object passed to it
- (B) a call to that function from a module passing a lambda twice in the same enclosing scope
This will cause the following compiler error: greetings.cpp:6:6: error: definition with same mangled name '_ZW9greetingsE5greetIZW_0E4testvEUt_EvT_' as another definition
This happens only if the use in (B) is part of a module as well (it can be an implementation unit of the same module, or it can also be part of a second module test which will trigger the error as well).
This seems to be some kind of variation of the following long closed bug: https://bugs.llvm.org/show_bug.cgi?id=33924
greetings.cpp
export module greetings;
import <string>;
export template <class Func>
void greet(Func f)
{
return f("Hello, World!");
}
test.cpp
module greetings;
// this would trigger the error as well:
// export module test;
import <iostream>;
int test()
{
greet([](const std::string& text) { std::cout << text << '\n'; });
greet([](const std::string& text) { std::cout << text << '\n'; });
return 1;
}
Compilation commands:
clang++ -Wall -std=c++2a -stdlib=libc++ -fimplicit-modules -fimplicit-module-maps -fmodules --precompile -x c++-module greetings.cpp -o greetings.pcm
clang++ -Wall -std=c++2a -stdlib=libc++ -fimplicit-modules -fimplicit-module-maps -fmodule-file=greetings.pcm -c test.cpp -o test.o
Alternate command if test.cpp is meant to be part of a different module:
clang++ -Wall -std=c++2a -stdlib=libc++ -fimplicit-modules -fimplicit-module-maps -fprebuilt-module-path=. -c test.cpp -o test.o