Objective-C. Make diagnostics and fix-its consistent

when diagnosing casting of a cstring literal to
NSString in default and -fobjc-arc mode. 
// rdar://14106083

llvm-svn: 197515

Author: Fariborz Jahanian

clang/include/clang/Basic/DiagnosticGroups.td

@@ -609,8 +609,6 @@ def ObjCLiteralComparison : DiagGroup<"objc-literal-compare", [
     ObjCStringComparison
   ]>;
 
-def ObjCLiteralMissingAtSign : DiagGroup<"objc-literal-missing-atsign">;
-
 // Inline ASM warnings.
 def ASMOperandWidths : DiagGroup<"asm-operand-widths">;
 def ASM : DiagGroup<"asm", [

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -1911,8 +1911,8 @@ def warn_objc_literal_comparison : Warning<
   "direct comparison of %select{an array literal|a dictionary literal|"
   "a numeric literal|a boxed expression|}0 has undefined behavior">,
   InGroup<ObjCLiteralComparison>;
-def warn_missing_atsign_prefix : Warning<
-  "string literal must be prefixed by '@' ">, InGroup<ObjCLiteralMissingAtSign>;
+def err_missing_atsign_prefix : Error<
+  "string literal must be prefixed by '@' ">;
 def warn_objc_string_literal_comparison : Warning<
   "direct comparison of a string literal has undefined behavior">, 
   InGroup<ObjCStringComparison>;

clang/include/clang/Sema/Sema.h

@@ -6900,6 +6900,10 @@ class Sema {
                                          QualType DestType, QualType SrcType,
                                          Expr *&SrcExpr);
 
+  StringLiteral * ConversionToObjCStringLiteralCheck(QualType DstType,
+                                          Expr *SrcExpr, FixItHint &Hint,
+                                          bool &IsNSString);
+  
   bool checkInitMethod(ObjCMethodDecl *method, QualType receiverTypeIfCall);
 
   /// \brief Check whether the given new method is a valid override of the

clang/lib/Sema/SemaExpr.cpp

@@ -10587,22 +10587,23 @@ ExprResult Sema::ActOnGNUNullExpr(SourceLocation TokenLoc) {
   return Owned(new (Context) GNUNullExpr(Ty, TokenLoc));
 }
 
-static void MakeObjCStringLiteralFixItHint(Sema& SemaRef, QualType DstType,
-                                           Expr *SrcExpr, FixItHint &Hint,
-                                           bool &IsNSString) {
-  if (!SemaRef.getLangOpts().ObjC1)
-    return;
+StringLiteral *
+Sema::ConversionToObjCStringLiteralCheck(QualType DstType,
+                                     Expr *SrcExpr, FixItHint &Hint,
+                                     bool &IsNSString) {
+  if (!getLangOpts().ObjC1)
+    return 0;
 
   const ObjCObjectPointerType *PT = DstType->getAs<ObjCObjectPointerType>();
   if (!PT)
-    return;
+    return 0;
 
   // Check if the destination is of type 'id'.
   if (!PT->isObjCIdType()) {
     // Check if the destination is the 'NSString' interface.
     const ObjCInterfaceDecl *ID = PT->getInterfaceDecl();
     if (!ID || !ID->getIdentifier()->isStr("NSString"))
-      return;
+      return 0;
     IsNSString = true;
   }
 
@@ -10616,9 +10617,9 @@ static void MakeObjCStringLiteralFixItHint(Sema& SemaRef, QualType DstType,
 
   StringLiteral *SL = dyn_cast<StringLiteral>(SrcExpr);
   if (!SL || !SL->isAscii())
-    return;
-
+    return 0;
   Hint = FixItHint::CreateInsertion(SL->getLocStart(), "@");
+  return SL;
 }
 
 bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
@@ -10655,7 +10656,7 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
     MayHaveConvFixit = true;
     break;
   case IncompatiblePointer:
-    MakeObjCStringLiteralFixItHint(*this, DstType, SrcExpr, Hint, IsNSString);
+    ConversionToObjCStringLiteralCheck(DstType, SrcExpr, Hint, IsNSString);
       DiagKind =
         (Action == AA_Passing_CFAudited ?
           diag::err_arc_typecheck_convert_incompatible_pointer :
@@ -10670,7 +10671,7 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
       DstType = DstType.getUnqualifiedType();
     }
     else if (IsNSString && !Hint.isNull())
-      DiagKind = diag::warn_missing_atsign_prefix;
+      DiagKind = diag::err_missing_atsign_prefix;
     MayHaveConvFixit = true;
     break;
   case IncompatiblePointerSign:

clang/lib/Sema/SemaExprObjC.cpp

@@ -3612,6 +3612,17 @@ Sema::CheckObjCARCConversion(SourceRange castRange, QualType castType,
       CCK != CCK_ImplicitConversion)
     return ACR_unbridged;
 
+  // Do not issue bridge cast" diagnostic when implicit casting a cstring
+  // to 'NSString *'. Let caller issue a normal mismatched diagnostic with
+  // suitable fix-it.
+  if (castACTC == ACTC_retainable && exprACTC == ACTC_none) {
+    bool IsNSString = false;
+    FixItHint Hint;
+    if (ConversionToObjCStringLiteralCheck(
+          castType, castExpr, Hint, IsNSString) && IsNSString)
+      return ACR_okay;
+  }
+  
   // Do not issue "bridge cast" diagnostic when implicit casting
   // a retainable object to a CF type parameter belonging to an audited
   // CF API function. Let caller issue a normal type mismatched diagnostic

clang/test/FixIt/fixit-objc-arc.m

@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -pedantic -verify %s
+// RUN: cp %s %t
+// RUN: not %clang_cc1 -pedantic -fobjc-arc -fixit -x objective-c %t
+// RUN: %clang_cc1 -pedantic -fobjc-arc -Werror -x objective-c %t
+// rdar://14106083
+
+@class A;
+@class NSString;
+
+@interface Test
+- (void)test:(NSString *)string; // expected-note{{passing argument to parameter 'string' here}}
+
+@property (copy) NSString *property;
+@end
+
+void g(NSString *a); // expected-note{{passing argument to parameter 'a' here}}
+void h(id a);
+
+void f(Test *t) {
+  NSString *a = "Foo"; // expected-error {{string literal must be prefixed by '@'}}
+  g("Foo"); // expected-error {{string literal must be prefixed by '@'}}
+  [t test:"Foo"]; // expected-error {{string literal must be prefixed by '@'}}
+  t.property = "Foo"; // expected-error {{string literal must be prefixed by '@'}}
+}

clang/test/FixIt/fixit-objc.m

@@ -27,13 +27,13 @@ - (void)test:(NSString *)string; // expected-note{{passing argument to parameter
 void h(id a); // expected-note 2{{passing argument to parameter 'a' here}}
 
 void f(Test *t) {
-  NSString *a = "Foo"; // expected-warning {{string literal must be prefixed by '@'}}
+  NSString *a = "Foo"; // expected-error {{string literal must be prefixed by '@'}}
   id b = "Foo"; // expected-warning {{incompatible pointer types initializing 'id' with an expression of type 'char [4]'}}
-  g("Foo"); // expected-warning {{string literal must be prefixed by '@'}}
+  g("Foo"); // expected-error {{string literal must be prefixed by '@'}}
   h("Foo"); // expected-warning{{incompatible pointer types passing 'char [4]' to parameter of type 'id'}}
   h(("Foo")); // expected-warning{{incompatible pointer types passing 'char [4]' to parameter of type 'id'}}
-  [t test:"Foo"]; // expected-warning {{string literal must be prefixed by '@'}}
-  t.property = "Foo"; // expected-warning {{string literal must be prefixed by '@'}}
+  [t test:"Foo"]; // expected-error {{string literal must be prefixed by '@'}}
+  t.property = "Foo"; // expected-error {{string literal must be prefixed by '@'}}
 
   // <rdar://problem/6896493>
   [t test:@"Foo"]]; // expected-error{{extraneous ']' before ';'}}