ObjC Class Property: diagnostics when accessing a class property using instance.

When a class property is accessed with an object instance, before this commit,
we try to apply a typo correction of the same property:
property 'c' not found on object of type 'A *'; did you mean 'c'?

With this commit, we correctly emit a diagnostics:
property 'c' is a class property; did you mean to access it with class 'A'?

rdar://26866973

llvm-svn: 274076

1 files changed, 24 insertions, 7 deletions

diff --git a/clang/lib/Sema/SemaExprObjC.cpp b/clang/lib/Sema/SemaExprObjC.cpp
index 598ae2098aa..8f0d4ff6957 100644
--- a/clang/lib/Sema/SemaExprObjC.cpp
+++ b/clang/lib/Sema/SemaExprObjC.cpp
@@ -1817,7 +1817,7 @@ HandleExprPropertyRefExpr(const ObjCObjectPointerType *OPT,
   Selector Sel = PP.getSelectorTable().getNullarySelector(Member);
   ObjCMethodDecl *Getter = IFace->lookupInstanceMethod(Sel);
   
-  // May be founf in property's qualified list.
+  // May be found in property's qualified list.
   if (!Getter)
     Getter = LookupMethodInQualifiedType(Sel, OPT, true);
 
@@ -1837,7 +1837,7 @@ HandleExprPropertyRefExpr(const ObjCObjectPointerType *OPT,
                                            PP.getSelectorTable(), Member);
   ObjCMethodDecl *Setter = IFace->lookupInstanceMethod(SetterSel);
       
-  // May be founf in property's qualified list.
+  // May be found in property's qualified list.
   if (!Setter)
     Setter = LookupMethodInQualifiedType(SetterSel, OPT, true);
   
@@ -1885,12 +1885,29 @@ HandleExprPropertyRefExpr(const ObjCObjectPointerType *OPT,
                       LookupOrdinaryName, nullptr, nullptr,
                       llvm::make_unique<DeclFilterCCC<ObjCPropertyDecl>>(),
                       CTK_ErrorRecovery, IFace, false, OPT)) {
-    diagnoseTypo(Corrected, PDiag(diag::err_property_not_found_suggest)
-                              << MemberName << QualType(OPT, 0));
     DeclarationName TypoResult = Corrected.getCorrection();
-    return HandleExprPropertyRefExpr(OPT, BaseExpr, OpLoc,
-                                     TypoResult, MemberLoc,
-                                     SuperLoc, SuperType, Super);
+    if (TypoResult.isIdentifier() &&
+        TypoResult.getAsIdentifierInfo() == Member) {
+      // There is no need to try the correction if it is the same.
+      NamedDecl *ChosenDecl =
+        Corrected.isKeyword() ? nullptr : Corrected.getFoundDecl();
+      if (ChosenDecl && isa<ObjCPropertyDecl>(ChosenDecl))
+        if (cast<ObjCPropertyDecl>(ChosenDecl)->isClassProperty()) {
+          // This is a class property, we should not use the instance to
+          // access it.
+          Diag(MemberLoc, diag::err_class_property_found) << MemberName
+          << OPT->getInterfaceDecl()->getName()
+          << FixItHint::CreateReplacement(BaseExpr->getSourceRange(),
+                                          OPT->getInterfaceDecl()->getName());
+          return ExprError();
+        }
+    } else {
+      diagnoseTypo(Corrected, PDiag(diag::err_property_not_found_suggest)
+                                << MemberName << QualType(OPT, 0));
+      return HandleExprPropertyRefExpr(OPT, BaseExpr, OpLoc,
+                                       TypoResult, MemberLoc,
+                                       SuperLoc, SuperType, Super);
+    }
   }
   ObjCInterfaceDecl *ClassDeclared;
   if (ObjCIvarDecl *Ivar =