================
@@ -10057,15 +10057,18 @@ void ASTReader::finishPendingActions() {
// For a function defined inline within a class template, force the
// canonical definition to be the one inside the canonical definition of
// the template. This ensures that we instantiate from a correct view
- // of the template.
+ // of the template. This behaviour seems to be important only for inline
+ // friend functions. For normal member functions, it might results in
+ // selecting canonical decl from module A but body from module B.
//
// Sadly we can't do this more generally: we can't be sure that all
// copies of an arbitrary class definition will have the same members
// defined (eg, some member functions may not be instantiated, and some
// special members may or may not have been implicitly defined).
- if (auto *RD = dyn_cast<CXXRecordDecl>(FD->getLexicalParent()))
- if (RD->isDependentContext() && !RD->isThisDeclarationADefinition())
- continue;
+ if (FD->getFriendObjectKind())
----------------
dmpolukhin wrote:
@ChuanqiXu9 and @ilya-biryukov I'm not sure that I fully understand the example
[test
case](https://github.com/llvm/llvm-project/blob/main/clang/test/Modules/friend-definition-2.cpp).
Do you understand what does the example really do?
Things unclear to me marked with `// >>>`.
```
// RUN: %clang_cc1 -std=c++14 -fmodules %s -verify
// RUN: %clang_cc1 -std=c++14 -fmodules %s -verify -triple i686-windows
// expected-no-diagnostics
// >>> it looks like undocumented pragma?
#pragma clang module build A
// >>> Is it modulemap file syntax?
module A {}
#pragma clang module contents
#pragma clang module begin A
// >>> What is the context of this code, is it GMF or part of module A, is it
implicitly exported?
template<typename T> struct ct { friend auto operator-(ct, ct) { struct X {};
return X(); } void x(); };
#pragma clang module end
#pragma clang module endbuild
#pragma clang module build B
module B {}
#pragma clang module contents
#pragma clang module begin B
// >>> Seems like it was part of GMF otherwise it is duplicating declaration?
template<typename T> struct ct { friend auto operator-(ct, ct) { struct X{};
return X(); } void x(); };
inline auto f() { return ct<float>() - ct<float>(); }
#pragma clang module end
#pragma clang module endbuild
// >>> Seems like here we are in different translation unit
// Force the definition of ct in module A to be the primary definition.
#pragma clang module import A
// >>> Why does it define something from module A !?
// >>> Should we see here error like: `declaration of 'x' in the global module
follows declaration in module A`
template<typename T> void ct<T>::x() {}
// Attempt to cause the definition of operator- in the ct primary template in
// module B to be the primary definition of that function. If that happens,
// we'll be left with a class template ct that appears to not contain a
// definition of the inline friend function.
#pragma clang module import B
auto v = f();
ct<int> make();
void h() {
make() - make();
}
```
https://github.com/llvm/llvm-project/pull/111992
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