That's a mouthful, and not necessarily the final name. This also
reflects a semantic change where this attribute is now on the
protocol itself instead of a class. This attribute will require
that a protocol, when adopted by a class, is explicitly implemented
by the class itself (instead of walking the super class chain).
Note that this attribute is not "done". This should be considered
a WIP.
llvm-svn: 196955
This is still an experimental attribute, but I wanted it in tree
for review. It may still get yanked.
This attribute can only be applied to a class @interface, not
a class extension or category. It does not change the type
system rules for Objective-C, but rather the implementation checking
for Objective-C classes that explicitly conform to a protocol.
During protocol conformance checking, clang recursively searches
up the class hierarchy for the set of methods that compose
a protocol. This attribute will cause the compiler to not consider
the methods contributed by a super class, its categories, and those
from its ancestor classes. Thus this attribute is used to force
subclasses to redeclare (and hopefully re-implement) methods if
they decide to explicitly conform to a protocol where some of those
methods may be provided by a super class.
This attribute intentionally leaves out properties, which are associated
with state. This attribute only considers methods (at least right now)
that are non-property accessors. These represent methods that "do something"
as dictated by the protocol. This may be further refined, and this
should be considered a WIP until documentation gets written or this
gets removed.
llvm-svn: 195533
After implementing this patch, a few concerns about the language
feature itself emerged in my head that I had previously not considered.
I want to resolve those design concerns first before having
a half-designed language feature in the tree.
llvm-svn: 195328
The idea is to allow a class to stipulate that its methods (and those
of its parents) cannot be used for protocol conformance in a subclass.
A subclass is then explicitly required to re-implement those methods
of they are present in the class marked with this attribute.
Currently the attribute can only be applied to an @interface, and
not a category or class extension. This is by design. Unlike
protocol conformance, where a category can add explicit conformance
of a protocol to class, this anti-conformance really needs to be
observed uniformly by all clients of the class. That's because
the absence of the attribute implies more permissive checking of
protocol conformance.
This unfortunately required changing method lookup in ObjCInterfaceDecl
to take an optional protocol parameter. This should not slow down
method lookup in most cases, and is just used for protocol conformance.
llvm-svn: 195323
Ted Kremenek