[C++20] [Modules] Clang didn't generate the virtual table to the unit containing the key function #70585
Description
Reproducer:
// layer1.cppm export module foo:layer1; struct Fruit { virtual ~Fruit() = default; virtual void eval() = 0; }; struct Banana : public Fruit { Banana() {} void eval() override; }; // layer2.cppm export module foo:layer2; import :layer1; export void layer2_fun() { Banana *b = new Banana(); b->eval(); } void Banana::eval() { } Compiler layer2.cppm with:
clang++ -std=c++20 layer1.cppm --precompile -o foo-layer1.pcm clang++ -std=c++20 layer2.cppm -fprebuilt-module-path=. -S -emit-llvm -o - Then we can't see anything about the definition of virtual table. This violates the itanium ABI 5.2.3:
The virtual table for a class is emitted in the same object containing the definition of its key function, i.e. the first non-pure virtual function that is not inline at the point of class definition.