Define weak and __weak to mean ARC-style weak references, even in MRC.

Previously, __weak was silently accepted and ignored in MRC mode.
That makes this a potentially source-breaking change that we have to
roll out cautiously.  Accordingly, for the time being, actual support
for __weak references in MRC is experimental, and the compiler will
reject attempts to actually form such references.  The intent is to
eventually enable the feature by default in all non-GC modes.
(It is, of course, incompatible with ObjC GC's interpretation of
__weak.)

If you like, you can enable this feature with
  -Xclang -fobjc-weak
but like any -Xclang option, this option may be removed at any point,
e.g. if/when it is eventually enabled by default.

This patch also enables the use of the ARC __unsafe_unretained qualifier
in MRC.  Unlike __weak, this is being enabled immediately.  Since
variables are essentially __unsafe_unretained by default in MRC,
the only practical uses are (1) communication and (2) changing the
default behavior of by-value block capture.

As an implementation matter, this means that the ObjC ownership
qualifiers may appear in any ObjC language mode, and so this patch
removes a number of checks for getLangOpts().ObjCAutoRefCount
that were guarding the processing of these qualifiers.  I don't
expect this to be a significant drain on performance; it may even
be faster to just check for these qualifiers directly on a type
(since it's probably in a register anyway) than to do N dependent
loads to grab the LangOptions.

rdar://9674298

llvm-svn: 251041

6 files changed, 77 insertions, 27 deletions

diff --git a/clang/test/SemaObjC/attr-objc-gc.m b/clang/test/SemaObjC/attr-objc-gc.m
index 827945c668c..303dce0d875 100644
--- a/clang/test/SemaObjC/attr-objc-gc.m
+++ b/clang/test/SemaObjC/attr-objc-gc.m
@@ -9,13 +9,13 @@ static id __attribute((objc_gc(hello))) f; // expected-warning{{'objc_gc' attrib
 
 static int __attribute__((objc_gc(weak))) g; // expected-warning {{'objc_gc' only applies to pointer types; type here is 'int'}}
 
-static __weak int h; // expected-warning {{'__weak' only applies to pointer types; type here is 'int'}}
+static __weak int h; // expected-warning {{'__weak' only applies to Objective-C object or block pointer types; type here is 'int'}}
 
 // TODO: it would be great if this reported as __weak
 #define WEAK __weak
-static WEAK int h; // expected-warning {{'objc_gc' only applies to pointer types; type here is 'int'}}
+static WEAK int h; // expected-warning {{'objc_ownership' only applies to Objective-C object or block pointer types; type here is 'int'}}
 
-/* expected-warning {{'__weak' only applies to pointer types; type here is 'int'}}*/ static __we\
+/* expected-warning {{'__weak' only applies to Objective-C object or block pointer types; type here is 'int'}}*/ static __we\
 ak int i;
 
 // rdar://problem/9126213
diff --git a/clang/test/SemaObjC/mrc-weak.m b/clang/test/SemaObjC/mrc-weak.m
new file mode 100644
index 00000000000..ec03cf7f002
--- /dev/null
+++ b/clang/test/SemaObjC/mrc-weak.m
@@ -0,0 +1,67 @@
+// RUN: %clang_cc1 -fobjc-runtime-has-weak -fobjc-weak -fsyntax-only -verify %s
+
+__attribute__((objc_root_class))
+@interface A
+@property (weak) id wa; // expected-note {{property declared here}}
+@property (weak) id wb;
+@property (weak) id wc; // expected-note {{property declared here}}
+@property (weak) id wd;
+@property (unsafe_unretained) id ua;
+@property (unsafe_unretained) id ub; // expected-note {{property declared here}}
+@property (unsafe_unretained) id uc;
+@property (unsafe_unretained) id ud;
+@property (strong) id sa;
+@property (strong) id sb; // expected-note {{property declared here}}
+@property (strong) id sc; // expected-note {{property declared here}}
+@property (strong) id sd;
+@end
+
+@implementation A {
+  id _wa; // expected-error {{existing instance variable '_wa' for __weak property 'wa' must be __weak}}
+  __weak id _wb;
+  __unsafe_unretained id _wc; // expected-error {{existing instance variable '_wc' for __weak property 'wc' must be __weak}}
+  id _ua;
+  __weak id _ub; // expected-error {{existing instance variable '_ub' for property 'ub' with unsafe_unretained attribute must be __unsafe_unretained}}
+  __unsafe_unretained id _uc;
+  id _sa;
+  __weak id _sb; // expected-error {{existing instance variable '_sb' for strong property 'sb' may not be __weak}}
+  __unsafe_unretained id _sc; // expected-error {{existing instance variable '_sc' for strong property 'sc' may not be __unsafe_unretained}}
+}
+@synthesize wa = _wa; // expected-note {{property synthesized here}}
+@synthesize wb = _wb;
+@synthesize wc = _wc; // expected-note {{property synthesized here}}
+@synthesize wd = _wd;
+@synthesize ua = _ua;
+@synthesize ub = _ub; // expected-note {{property synthesized here}}
+@synthesize uc = _uc;
+@synthesize ud = _ud;
+@synthesize sa = _sa;
+@synthesize sb = _sb; // expected-note {{property synthesized here}}
+@synthesize sc = _sc; // expected-note {{property synthesized here}}
+@synthesize sd = _sd;
+@end
+
+void test_goto() {
+  goto after; // expected-error {{cannot jump from this goto statement to its label}}
+  __weak id x; // expected-note {{jump bypasses initialization of __weak variable}}}
+after:
+  return;
+}
+
+void test_weak_cast(id *value) {
+  __weak id *a = (__weak id*) value;
+  id *b = (__weak id*) value; // expected-error {{initializing 'id *' with an expression of type '__weak id *' changes retain/release properties of pointer}}
+  __weak id *c = (id*) value; // expected-error {{initializing '__weak id *' with an expression of type 'id *' changes retain/release properties of pointer}}
+}
+
+void test_unsafe_unretained_cast(id *value) {
+  __unsafe_unretained id *a = (__unsafe_unretained id*) value;
+  id *b = (__unsafe_unretained id*) value;
+  __unsafe_unretained id *c = (id*) value;
+}
+
+void test_cast_qualifier_inference(__weak id *value) {
+  __weak id *a = (id*) value;
+  __unsafe_unretained id *b = (id*) value; // expected-error {{initializing '__unsafe_unretained id *' with an expression of type '__weak id *' changes retain/release properties of pointer}}
+}
+
diff --git a/clang/test/SemaObjC/no-gc-weak-test.m b/clang/test/SemaObjC/no-gc-weak-test.m
index 6539a9b7f14..287b4db8cef 100644
--- a/clang/test/SemaObjC/no-gc-weak-test.m
+++ b/clang/test/SemaObjC/no-gc-weak-test.m
@@ -1,11 +1,10 @@
 // RUN: %clang_cc1 -triple i386-apple-darwin9 -fsyntax-only -verify -Wno-objc-root-class %s
-// expected-no-diagnostics
 
 @interface Subtask
 {
   id _delegate;
 }
-@property(nonatomic,readwrite,assign)   id __weak       delegate;
+@property(nonatomic,readwrite,assign)   id __weak       delegate;  // expected-error {{the current deployment target does not support automated __weak references}}
 @end
 
 @implementation Subtask
@@ -15,15 +14,15 @@
  
 @interface PVSelectionOverlayView2 
 {
- id __weak _selectionRect;
+ id __weak _selectionRect;  // expected-error {{the current deployment target does not support automated __weak references}} expected-error {{existing instance variable '_selectionRect' for property 'selectionRect' with assign attribute must be __unsafe_unretained}}
 }
 
-@property(assign) id selectionRect;
+@property(assign) id selectionRect; // expected-note {{property declared here}}
 
 @end
 
 @implementation PVSelectionOverlayView2
 
-@synthesize selectionRect = _selectionRect;
+@synthesize selectionRect = _selectionRect; // expected-note {{property synthesized here}}
 @end
 
diff --git a/clang/test/SemaObjC/nonarc-weak.m b/clang/test/SemaObjC/nonarc-weak.m
deleted file mode 100644
index ab51875de1c..00000000000
--- a/clang/test/SemaObjC/nonarc-weak.m
+++ /dev/null
@@ -1,16 +0,0 @@
-// RUN: %clang_cc1 -triple x86_64-apple-macosx10.8.0 -fobjc-runtime=macosx-10.8.0 -fsyntax-only -Wunused-function %s > %t.nonarc 2>&1
-// RUN: %clang_cc1 -triple x86_64-apple-macosx10.8.0 -fobjc-runtime=macosx-10.8.0 -fsyntax-only -Wunused-function -fobjc-arc %s > %t.arc 2>&1
-// RUN: FileCheck -input-file=%t.nonarc %s
-// RUN: FileCheck -input-file=%t.arc -check-prefix=ARC %s
-
-static void bar() {} // Intentionally unused.
-
-void foo(id self) {
-  __weak id weakSelf = self;
-}
-
-// CHECK: 9:13: warning: __weak attribute cannot be specified on an automatic variable when ARC is not enabled
-// CHECK: 6:13: warning: unused function 'bar'
-// CHECK: 2 warnings generated
-// ARC: 6:13: warning: unused function 'bar'
-// ARC: 1 warning generated
diff --git a/clang/test/SemaObjC/property-in-class-extension-1.m b/clang/test/SemaObjC/property-in-class-extension-1.m
index ab461ef6c19..6e9d476c18a 100644
--- a/clang/test/SemaObjC/property-in-class-extension-1.m
+++ b/clang/test/SemaObjC/property-in-class-extension-1.m
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1  -fsyntax-only -triple x86_64-apple-darwin11 -fobjc-runtime-has-weak -verify -Weverything %s
-// RUN: %clang_cc1 -x objective-c++ -triple x86_64-apple-darwin11 -fobjc-runtime-has-weak -fsyntax-only -verify -Weverything %s
+// RUN: %clang_cc1  -fsyntax-only -triple x86_64-apple-darwin11 -fobjc-runtime-has-weak -fobjc-weak -verify -Weverything -Wno-objc-weak-compat  %s
+// RUN: %clang_cc1 -x objective-c++ -triple x86_64-apple-darwin11 -fobjc-runtime-has-weak -fobjc-weak -fsyntax-only -verify -Weverything -Wno-objc-weak-compat %s
 // rdar://12103400
 
 @class NSString;
diff --git a/clang/test/SemaObjC/synthesized-ivar.m b/clang/test/SemaObjC/synthesized-ivar.m
index 884a3caf0f6..cc7b309da03 100644
--- a/clang/test/SemaObjC/synthesized-ivar.m
+++ b/clang/test/SemaObjC/synthesized-ivar.m
@@ -57,5 +57,5 @@ int f0(I *a) { return a->IP; } // expected-error {{instance variable 'IP' is pri
 
 @implementation A
 // rdar://9605088
-@synthesize testObjectWeakProperty; // expected-error {{@synthesize of 'weak' property is only allowed in ARC or GC mode}}
+@synthesize testObjectWeakProperty; // expected-error {{the current deployment target does not support automated __weak references}}
 @end