objective-c: warn when autosynthesizing a property which has same

name as an existing ivar since this is common source of error
when people remove @synthesize to take advantage of autosynthesis. 
// rdar://11671080


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158756 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/Sema/SemaObjCProperty.cpp b/lib/Sema/SemaObjCProperty.cpp
index 84dc9cae23..20dbf58c98 100644
--- a/lib/Sema/SemaObjCProperty.cpp
+++ b/lib/Sema/SemaObjCProperty.cpp
@@ -755,6 +755,22 @@ Decl *Sema::ActOnPropertyImplDecl(Scope *S,
     }
 
     if (!Ivar) {
+      if (AtLoc.isInvalid()) {
+        // Check when default synthesizing a property that there is 
+        // an ivar matching property name and issue warning; since this
+        // is the most common case of not using an ivar used for backing
+        // property in non-default synthesis case.
+        ObjCInterfaceDecl *ClassDeclared=0;
+        ObjCIvarDecl *originalIvar = 
+          IDecl->lookupInstanceVariable(property->getIdentifier(), 
+                                        ClassDeclared);
+        if (originalIvar) {
+          Diag(PropertyDiagLoc, 
+               diag::warn_autosynthesis_property_ivar_match);
+          Diag(property->getLocation(), diag::note_property_declare);
+          Diag(originalIvar->getLocation(), diag::note_ivar_decl);
+        }
+      }
       // In ARC, give the ivar a lifetime qualifier based on the
       // property attributes.
       if (getLangOpts().ObjCAutoRefCount &&