[Sema][ObjC] Do not DiagnoseUseOfDecl in LookupMemberExpr

[steven_wu]

Summary

Remove the call to DiagnoseUseOfDecl in LookupMemberExpr because:

1. LookupMemberExpr eagerly lookup both getter and setter, reguardless

if they are used or not. It causes wrong diagnostics if you are only
using getter.

2. LookupMemberExpr only diagnoses getter, but not setter.
3. ObjCPropertyOpBuilder already DiagnoseUseOfDecl when building getter

and setter. Doing it again in LookupMemberExpr causes duplicated
diagnostics.

rdar://problem/38479756

[arphaman]

LGTM.

lib/Sema/SemaExprMember.cpp

if (OT->isObjCId()) {
             return ExprError();
 
           return new (S.Context)
               ObjCPropertyRefExpr(PD, S.Context.PseudoObjectTy, VK_LValue,
                                   OK_ObjCProperty, MemberLoc, BaseExpr.get());
         }
 
         if (ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(PMDecl)) {
-          // Check the use of this method.
-          if (S.DiagnoseUseOfDecl(OMD, MemberLoc))
-            return ExprError();
           Selector SetterSel =
             SelectorTable::constructSetterSelector(S.PP.getIdentifierTable(),
                                                    S.PP.getSelectorTable(),
                                                    Member);
           ObjCMethodDecl *SMD = nullptr;
           if (Decl *SDecl = FindGetterSetterNameDecl(OPT,
                                                      /*Property id*/ nullptr,
                                                      SetterSel, S.Context))

test/SemaObjC/property-deprecated-warning.m

 }
 @end
 
 void testUserAccessorAttributes(Foo *foo) {
         [foo setX:5678]; // expected-warning {{'setX:' is deprecated}}
   foo.x = foo.x; // expected-error {{property access is using 'x' method which is unavailable}} \
            // expected-warning {{property access is using 'setX:' method which is deprecated}}
 }
+
+// test implicit property does not emit duplicated warning.
+@protocol Foo
+- (int)size __attribute__((availability(ios,deprecated=3.0))); // expected-note {{'size' has been explicitly marked deprecated here}}
+- (void)setSize: (int)x __attribute__((availability(ios,deprecated=2.0))); // expected-note {{'setSize:' has been explicitly marked deprecated here}}
+@end
+
+void testImplicitProperty(id<Foo> object) {
+  object.size = object.size; // expected-warning {{'size' is deprecated: first deprecated in iOS 3.0}} \
+                             // expected-warning {{'setSize:' is deprecated: first deprecated in iOS 2.0}}
+}