llvm-project

0bfcc5c1 - [Clang] Add diagnostic for why std::is_abstract is false (#156199)

[Clang] Add diagnostic for why std::is_abstract is false (#156199) Explain why a type is not abstract. Handles arrays, refs, unions, pointers, and functions. If the non-abstract type has abstract base classes, point out that their pure virtual methods must have been overridden. Adds onto #141911