objective-c: If an ivar is (1) the first ivar in a root class and (2) named `isa`, 
then it should get the same warnings that id->isa gets. // rdar://11702488


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158938 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaExprMember.cpp b/lib/Sema/SemaExprMember.cpp
index 22b2315..d5e83ce 100644
--- a/lib/Sema/SemaExprMember.cpp
+++ b/lib/Sema/SemaExprMember.cpp
@@ -1149,7 +1149,20 @@
                                 ObjCImpDecl, HasTemplateArgs);
       goto fail;
     }
-
+    else if (Member && Member->isStr("isa")) {
+      // If an ivar is (1) the first ivar in a root class and (2) named `isa`,
+      // then issue the same deprecated warning that id->isa gets.
+      ObjCInterfaceDecl *ClassDeclared = 0;
+      if (ObjCIvarDecl *IV = 
+            IDecl->lookupInstanceVariable(Member, ClassDeclared)) {
+        if (!ClassDeclared->getSuperClass()
+            && (*ClassDeclared->ivar_begin()) == IV) {
+          Diag(MemberLoc, diag::warn_objc_isa_use);
+          Diag(IV->getLocation(), diag::note_ivar_decl);
+        }
+      }
+    }
+    
     if (RequireCompleteType(OpLoc, BaseType, diag::err_typecheck_incomplete_tag,
                             BaseExpr.get()))
       return ExprError();
diff --git a/test/SemaObjC/id-isa-ref.m b/test/SemaObjC/id-isa-ref.m
deleted file mode 100644
index c2debb0..0000000
--- a/test/SemaObjC/id-isa-ref.m
+++ /dev/null
@@ -1,35 +0,0 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
-
-typedef struct objc_object {
-  struct objc_class *isa;
-} *id;
-
-@interface NSObject {
-  struct objc_class *isa;
-}
-@end
-@interface Whatever : NSObject
-+self;
-@end
-
-static void func() {
- 
-  id x;
-
-  // rdar://8290002
-  [(*x).isa self]; // expected-warning {{direct access to objective-c's isa is deprecated in favor of object_setClass() and object_getClass()}}
-  [x->isa self]; // expected-warning {{direct access to objective-c's isa is deprecated in favor of object_setClass() and object_getClass()}}
-  
-  Whatever *y;
-
-  // GCC allows this, with the following warning: 
-  //   instance variable 'isa' is @protected; this will be a hard error in the future
-  //
-  // FIXME: see if we can avoid the 2 warnings that follow the error.
-  [(*y).isa self]; // expected-error {{instance variable 'isa' is protected}} \
-                      expected-warning{{receiver type 'struct objc_class *' is not 'id' or interface pointer, consider casting it to 'id'}} \
-                      expected-warning{{method '-self' not found (return type defaults to 'id')}}
-  [y->isa self]; // expected-error {{instance variable 'isa' is protected}} \
-                    expected-warning{{receiver type 'struct objc_class *' is not 'id' or interface pointer, consider casting it to 'id'}} \
-                    expected-warning{{method '-self' not found (return type defaults to 'id')}}
-}
diff --git a/test/SemaObjC/warn-isa-ref.m b/test/SemaObjC/warn-isa-ref.m
new file mode 100644
index 0000000..1932a02
--- /dev/null
+++ b/test/SemaObjC/warn-isa-ref.m
@@ -0,0 +1,83 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+typedef struct objc_object {
+  struct objc_class *isa;
+} *id;
+
+@interface NSObject {
+  id firstobj;
+  struct objc_class *isa;
+}
+@end
+@interface Whatever : NSObject
++self;
+@end
+
+static void func() {
+ 
+  id x;
+
+  // rdar://8290002
+  [(*x).isa self]; // expected-warning {{direct access to objective-c's isa is deprecated in favor of object_setClass() and object_getClass()}}
+  [x->isa self]; // expected-warning {{direct access to objective-c's isa is deprecated in favor of object_setClass() and object_getClass()}}
+  
+  Whatever *y;
+
+  // GCC allows this, with the following warning: 
+  //   instance variable 'isa' is @protected; this will be a hard error in the future
+  //
+  // FIXME: see if we can avoid the 2 warnings that follow the error.
+  [(*y).isa self]; // expected-error {{instance variable 'isa' is protected}} \
+                      expected-warning{{receiver type 'struct objc_class *' is not 'id' or interface pointer, consider casting it to 'id'}} \
+                      expected-warning{{method '-self' not found (return type defaults to 'id')}}
+  [y->isa self]; // expected-error {{instance variable 'isa' is protected}} \
+                    expected-warning{{receiver type 'struct objc_class *' is not 'id' or interface pointer, consider casting it to 'id'}} \
+                    expected-warning{{method '-self' not found (return type defaults to 'id')}}
+}
+
+// rdar://11702488
+// If an ivar is (1) the first ivar in a root class and (2) named `isa`,
+// then it should get the same warnings that id->isa gets.
+
+@interface BaseClass {
+@public
+    Class isa; // expected-note 3 {{ivar is declared here}}
+}
+@end
+
+@interface OtherClass {
+@public
+    id    firstIvar;
+    Class isa; // note, not first ivar;
+}
+@end
+
+@interface Subclass : BaseClass @end
+
+@interface SiblingClass : BaseClass @end
+
+@interface Root @end
+
+@interface hasIsa : Root {
+@public
+  Class isa; // note, isa is not in root class
+}
+@end
+
+@implementation Subclass
+-(void)method {
+    hasIsa *u;
+    id v;
+    BaseClass *w;
+    Subclass *x;
+    SiblingClass *y;
+    OtherClass *z;
+    (void)v->isa; // expected-warning {{direct access to objective-c's isa is deprecated}}
+    (void)w->isa; // expected-warning {{direct access to objective-c's isa is deprecated}}
+    (void)x->isa; // expected-warning {{direct access to objective-c's isa is deprecated}}
+    (void)y->isa; // expected-warning {{direct access to objective-c's isa is deprecated}}
+    (void)z->isa;
+    (void)u->isa;
+}
+@end
+