ObjectiveC [QoI] issue warning if an element of an nsarray

expresison is a concatenated nsstring element.
// rdar://14303083

llvm-svn: 188332

clang/include/clang/Basic/DiagnosticGroups.td

@@ -552,6 +552,7 @@ def ObjCCocoaAPI : DiagGroup<"objc-cocoa-api", [
   ]>;
 
 def ObjCStringComparison : DiagGroup<"objc-string-compare">;
+def ObjCStringConcatenation : DiagGroup<"objc-string-concatenation">;
 def ObjCLiteralComparison : DiagGroup<"objc-literal-compare", [
     ObjCStringComparison
   ]>;

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -1898,6 +1898,9 @@ def warn_missing_atsign_prefix : Warning<
 def warn_objc_string_literal_comparison : Warning<
   "direct comparison of a string literal has undefined behavior">, 
   InGroup<ObjCStringComparison>;
+def warn_concatenated_nsarray_literal : Warning<
+  "concatenated nsstring literal for an nsarray expression">,
+  InGroup<ObjCStringConcatenation>;
 def note_objc_literal_comparison_isequal : Note<
   "use 'isEqual:' instead">;
 

clang/lib/Sema/SemaExprObjC.cpp

@@ -324,7 +324,8 @@ ExprResult Sema::ActOnObjCBoolLiteral(SourceLocation AtLoc,
 /// \brief Check that the given expression is a valid element of an Objective-C
 /// collection literal.
 static ExprResult CheckObjCCollectionLiteralElement(Sema &S, Expr *Element, 
-                                                    QualType T) {  
+                                                    QualType T,
+                                                    bool ArrayLiteral = false) {
   // If the expression is type-dependent, there's nothing for us to do.
   if (Element->isTypeDependent())
     return Element;
@@ -401,14 +402,20 @@ static ExprResult CheckObjCCollectionLiteralElement(Sema &S, Expr *Element,
         Recovered = true;
       }
     }
-    
+  
     if (!Recovered) {
       S.Diag(Element->getLocStart(), diag::err_invalid_collection_element)
         << Element->getType();
       return ExprError();
     }
   }
-  
+  if (ArrayLiteral)
+    if (ObjCStringLiteral *getString = dyn_cast<ObjCStringLiteral>(OrigElement)) {
+      if (getString->getString() && getString->getString()->getNumConcatenated() > 1)
+        S.Diag(Element->getLocStart(), diag::warn_concatenated_nsarray_literal)
+        << Element->getType();
+    }
+
   // Make sure that the element has the type that the container factory 
   // function expects. 
   return S.PerformCopyInitialization(
@@ -710,7 +717,7 @@ ExprResult Sema::BuildObjCArrayLiteral(SourceRange SR, MultiExprArg Elements) {
   for (unsigned I = 0, N = Elements.size(); I != N; ++I) {
     ExprResult Converted = CheckObjCCollectionLiteralElement(*this,
                                                              ElementsBuffer[I],
-                                                             RequiredType);
+                                                             RequiredType, true);
     if (Converted.isInvalid())
       return ExprError();
     

clang/test/SemaObjC/objc-array-literal.m

@@ -39,3 +39,9 @@ int main() {
   const char *blah;
   NSArray *array2 = @[blah]; // expected-error{{collection element of type 'const char *' is not an Objective-C object}}
 }
+
+// rdar://14303083
+id Test14303083() {
+  id obj = @[ @"A", (@"B" @"C")];
+  return @[ @"A", @"B" @"C"]; // expected-warning {{concatenated nsstring literal for an nsarray expression}}
+}