...which, somewhat arbitrarily, expects GNU extension __attribute__((...)) to
come before MSVC extension __declspec(...) with
MaybeParseGNUAttributes(attrs);
MaybeParseMicrosoftDeclSpecs(attrs);
in Parser::ParseClassSpecifier (lib/Parse/ParseDeclCXX.cpp).
Change-Id: I5936558c8fc08b278575b6c678cde6eccd4647fb