[PATCH] D65511: Delay emitting dllexport explicitly defaulted members until the class is fully parsed (PR40006)

[Alexandre Ganea via Phabricator via cfe-commits]

aganea added inline comments.


================
Comment at: clang/lib/Sema/SemaDeclCXX.cpp:11545
+    for (CXXMethodDecl *M : WorkList) {
+      DefineImplicitSpecialMember(*this, M, M->getLocation());
+      ActOnFinishInlineFunctionDef(M);
----------------
rnk wrote:
> hans wrote:
> > rnk wrote:
> > > Do we need to do this until fixpoint? Suppose a dllexported implicit special member triggers a template instantiation, and the template has a dllexported defaulted special member, something like:
> > > ```
> > > struct Bar { Bar(); };
> > > template <typename T> struct Foo { __declspec(dllexport) Foo() = default; Bar obj; };
> > > struct Baz {
> > >    ... not sure how to trigger instantiation
> > > };
> > > ```
> > I think that should work, and that's why the function is written to be re-entrant by having a local worklist. If it triggers a template instantiation, ActOnFinishCXXNonNestedClass should get called for the newly instantiated class. But I'm also not sure how to write a test case that would trigger it.
> Right, I see. Nevermind then.
This works on latest MSVC:
```
$ cat test.cc
struct Bar { Bar(); };
template <typename T> struct Foo { __declspec(dllexport) Foo() = default; Bar b; };
template class Foo<int>;

$ cl /c /Z7 test.cc   <-- crashes if using clang-cl

$ lib test.obj /def

$ cat test2.cc
struct Bar { Bar() { } };
template <typename T> struct Foo { __declspec(dllimport) Foo() = default; Bar b; };
int main() {
  Foo<int> f;
  return 0;
}

$ cl /c /Z7 test2.cc

$ link test.lib test2.cc /DEBUG
```


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D65511/new/

https://reviews.llvm.org/D65511