commit dd8297b0669f8e69b03ba40171b195b5acf0f963
    Author: Richard Smith <[email protected]>
    Date:   Fri Oct 30 18:30:56 2020 -0700

        PR42513: Fix handling of function definitions lazily instantiated from
        friends.

        When determining whether a function has a template instantiation
        pattern, look for other declarations of that function that were
        instantiated from a friend function definition, rather than assuming
        that checking for member specialization information on whichever
        declaration name lookup found will be sufficient.
 
     clang/include/clang/AST/Decl.h                 |  14 +++-
     clang/lib/AST/Decl.cpp                         |  61 ++++++++++++--
     clang/lib/Sema/SemaDecl.cpp                    |  84 +++++--------------
     clang/lib/Sema/SemaDeclCXX.cpp                 |  11 +++
     clang/lib/Sema/SemaTemplateInstantiateDecl.cpp | 110 ++++++++++++-------------
     clang/test/SemaTemplate/friend.cpp             |   7 ++
     6 files changed, 159 insertions(+), 128 deletions(-)