There were two assertions in DefaultArgStorage::setInherited previously.
It requires the DefaultArgument is either empty or an argument value. It
would crash if it has a pointer refers to the previous declaration or
contains a chain to the previous declaration.
But there are edge cases could hit them actually. One is
InheritDefaultArguments.cppm that I found recently. Another one is pr31469.cpp,
which was created fives years ago.
This patch tries to fix the two failures by handling full cases in
DefaultArgStorage::setInherited.
This is guaranteed to not introduce any breaking change since it lives
in the path we wouldn't touch before. And the added assertions for
sameness should keep the correctness.
Reviewed By: v.g.vassilev
Differential Revision: https://reviews.llvm.org/D128974
Fixes a crash in modules where the template class decl becomes the most recent
decl in the redeclaration chain and forcing the template instantiator try to
instantiate the friend declaration, rather than the template definition.
In practice, A::list<int> produces a TemplateSpecializationType
A::__1::list<int, allocator<type-parameter-0-0> >' failing to replace to
subsitute the default argument to allocator<int>.
Kudos Richard Smith (D28399).
llvm-svn: 291753
Chuanqi Xu