[PATCH] D67983: [ObjC] Diagnose implicit type coercion from ObjC 'Class' to object pointer types.

[James Y Knight via Phabricator via cfe-commits]

jyknight created this revision.
jyknight added a reviewer: rjmccall.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

For example, in Objective-C mode, the initialization of 'x' in:

  @implementation MyType
  + (void)someClassMethod {
    MyType *x = self;
  }
  @end

is correctly diagnosed with an incompatible-pointer-types warning, but
in Objective-C++ mode, it is not diagnosed at all -- even though
incompatible pointer conversions generally become an error in C++.

This patch fixes that oversight, allowing implicit conversions
involving Class only to/from unqualified-id, and between qualified and
unqualified Class, where the protocols are compatible.

Note that this does change some behaviors in Objective-C, as well, as
shown by the modified tests.

Of particular note is that assignment from from 'Class<MyProtocol>' to
'id<MyProtocol>' now warns. (Despite appearances, those are not
compatible types. 'Class<MyProtocol>' is not expected to have instance
methods defined by 'MyProtocol', while 'id<MyProtocol>' is.)


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D67983

Files:
  clang/lib/AST/ASTContext.cpp
  clang/lib/Sema/SemaExpr.cpp
  clang/test/SemaObjC/comptypes-1.m
  clang/test/SemaObjCXX/class-method-self.mm
  clang/test/SemaObjCXX/comptypes-1.mm
  clang/test/SemaObjCXX/comptypes-7.mm
  clang/test/SemaObjCXX/instancetype.mm

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