From 5e244eeac32619f73bb961d5688ac5d202329fbd Mon Sep 17 00:00:00 2001
From: Ted Kremenek <kremenek@apple.com>
Date: Thu, 9 Jan 2014 20:19:45 +0000
Subject: [PATCH] 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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@198888 91177308-0d34-0410-b5e6-96231b3b80d8
---
lib/Sema/SemaDecl.cpp | 3 ++-
test/SemaObjC/unused.m | 9 +++++++++
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index fb041ed98c8..78ead1ee92b 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -1268,7 +1268,8 @@ static bool ShouldDiagnoseUnusedDecl(const NamedDecl *D) {
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/test/SemaObjC/unused.m b/test/SemaObjC/unused.m
index 3fd1cf04673..16a38995ffd 100644
--- a/test/SemaObjC/unused.m
+++ b/test/SemaObjC/unused.m
@@ -72,3 +72,12 @@ static NSString *x = @"hi"; // expected-warning {{unused variable 'x'}}
- (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();
+}
+
--
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