Fix parsing of trailing-return-type. Types are syntactically prohibited from
being defined here: [] () -> struct S {} does not define struct S.

In passing, implement DR1318 (syntactic disambiguation of 'final').


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@152551 91177308-0d34-0410-b5e6-96231b3b80d8
11 files changed