[PATCH] D33191: [analyzer] ObjCGenerics: account for __kindof specifiers met along a chain of casts.

[Artem Dergachev via Phabricator via cfe-commits]

NoQ created this revision.
Herald added a subscriber: xazax.hun.

`__kindof` type specifiers allow the developers to express their intent in discriminating between generic type arguments being matched exactly or allowing sub-types. When generics were introduced, it was already too late to add `__kindof` specifiers consistently across all the code. So for now in most code we believe it's all right not to have them, but we need to expect to have them at least in some places (which would normally be API declarations) and pick them up when they're present by loosening our dynamic type information from non-`__kindof` to `__kindof`, which would suppress some of the false "invalid cast" warnings.

In the test provided, the `__kindof` is only present on the API return value; direct cast from the object created within the callee function is an error, however casting indirectly through a `__kindof` type should be possible, because just one `__kindof` annotation at the API declaration is considered to be enough to express the intent of "it was `__kindof` from the start but we didn't bother adding it".

For now, we discard the original type information when we find `__kindof` specifiers in a chain of casts.


https://reviews.llvm.org/D33191

Files:
  lib/StaticAnalyzer/Checkers/DynamicTypePropagation.cpp
  test/Analysis/generics.m

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