[Sema] Don't mark plain MS enums as fixed
Summary:
This fixes a flaw in our AST: PR27098
MSVC always gives plain enums the underlying type 'int'. Clang does this
as well, but we claim the enum is "fixed", as if the user actually wrote
': int'. It means we end up emitting spurious -Wsign-compare warnings on
code like this:
enum Vals { E1, E2, E3 };
bool f(unsigned v1, Vals v2) {
return v1 == v2;
}
We think 'v2' can take on negative values because we think 'Vals' is
fixed. This fixes that.
Reviewers: rsmith
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D43110
llvm-svn: 324913