This attribute, called "objc_externally_retained", exposes clang's
notion of pseudo-__strong variables in ARC. Pseudo-strong variables
"borrow" their initializer, meaning that they don't retain/release
it, instead assuming that someone else is keeping their value alive.
If a function is annotated with this attribute, implicitly strong
parameters of that function aren't implicitly retained/released in
the function body, and are implicitly const. This is useful to expose
for performance reasons, most functions don't need the extra safety
of the retain/release, so programmers can opt out as needed.
This attribute can also apply to declarations of local variables,
with similar effect.
Differential revision: https://reviews.llvm.org/D55865
llvm-svn: 350422
Fixed incorrect docs that referred to:
objc_arc_weak_unavailable
when it should be:
objc_arc_weak_reference_unavailable
Patch by: Sean McBride!
llvm-svn: 281227
Previously we allowed these casts only for constants declared in system
headers, which we assume are retain/release-neutral. Now also allow them
for constants in user headers, treating them as +0. Practically, this
means that we will now allow:
id x = (id)kMyGlobalConst;
But unlike with system headers we cannot mix them with +1 values:
id y = (id)(b ? kMyGlobalConst : [Obj newValAtPlusOne]); // error
id z = (id)(b ? kSystemGlobalConst: [Obj newValAtPlusOne]); // OK
Thanks to John for suggesting this improvement.
llvm-svn: 230534
of block declarators. Document the rule we use.
Also document the rule that Doug implemented a few weeks ago
which drops ownership qualifiers on function result types.
rdar://10127067
llvm-svn: 176336
that a __strong object of block type is a valid argument to objc_storeStrong but
that an objc_retain and not an objc_retainBlock will be emitted.
llvm-svn: 175838
Eugene Zelenko