Have attribute 'objc_precise_lifetime' suppress -Wunused.
Fixes <rdar://problem/15596883>
In ARC, __attribute__((objc_precise_lifetime)) guarantees that the
object stored in it will survive to the end of the variable's formal
lifetime. It is therefore useful even if it completely unused.
llvm-svn: 198888
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index fb041ed..78ead1e 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -1268,7 +1268,8 @@
if (D->isInvalidDecl())
return false;
- if (D->isReferenced() || D->isUsed() || D->hasAttr<UnusedAttr>())
+ if (D->isReferenced() || D->isUsed() || D->hasAttr<UnusedAttr>() ||
+ D->hasAttr<ObjCPreciseLifetimeAttr>())
return false;
if (isa<LabelDecl>(D))
diff --git a/clang/test/SemaObjC/unused.m b/clang/test/SemaObjC/unused.m
index 3fd1cf0..16a3899 100644
--- a/clang/test/SemaObjC/unused.m
+++ b/clang/test/SemaObjC/unused.m
@@ -72,3 +72,12 @@
- (void) b {}
- (void) a { [self b]; }
@end
+
+// Test that objc_precise_lifetime suppresses
+// unused variable warnings.
+extern void rdar15596883_foo(void);
+void rdar15596883(id x) {
+ __attribute__((objc_precise_lifetime)) id y = x; // no-warning
+ rdar15596883_foo();
+}
+