Downgrade the "direct comparison" error for ObjC literals to a warning.

Chris pointed out that while the comparison is certainly problematic
and does not have well-defined behavior, it isn't any worse than some
of the other abuses that we merely warn about and doesn't need to make
the compilation fail.

Revert the release notes change (r159766) now that this is just a new warning.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@159939 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 7 deletions

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 6dbf704765..fbd70a8d26 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -6739,7 +6739,7 @@ static DiagnosticBuilder diagnoseObjCLiteralComparison(Sema &S,
     llvm_unreachable("Unknown Objective-C object literal kind");
   }
 
-  return S.Diag(Loc, diag::err_objc_literal_comparison)
+  return S.Diag(Loc, diag::warn_objc_literal_comparison)
            << LiteralKind << CanFix << Literal->getSourceRange();
 }
 
@@ -6747,6 +6747,14 @@ static ExprResult fixObjCLiteralComparison(Sema &S, SourceLocation OpLoc,
                                            ExprResult &LHS,
                                            ExprResult &RHS,
                                            BinaryOperatorKind Op) {
+  // Check early to see if the warning's on.
+  // If it's off, we should /not/ be auto-applying the accompanying fixit.
+  DiagnosticsEngine::Level Level =
+    S.getDiagnostics().getDiagnosticLevel(diag::warn_objc_literal_comparison,
+                                          OpLoc);
+  if (Level == DiagnosticsEngine::Ignored)
+    return ExprEmpty();
+
   assert((Op == BO_EQ || Op == BO_NE) && "Cannot fix other operations.");
 
   // Get the LHS object's interface type.
@@ -8228,12 +8236,14 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
     break;
   case BO_EQ:
   case BO_NE:
-    if (isObjCObjectLiteral(LHS) || isObjCObjectLiteral(RHS)) {
-      ExprResult IsEqualCall = fixObjCLiteralComparison(*this, OpLoc,
-                                                        LHS, RHS, Opc);
-      if (IsEqualCall.isUsable())
-        return IsEqualCall;
-      // Otherwise, fall back to the normal diagnostic in CheckCompareOperands.
+    if (getLangOpts().ObjC1) {
+      if (isObjCObjectLiteral(LHS) || isObjCObjectLiteral(RHS)) {
+        ExprResult IsEqualCall = fixObjCLiteralComparison(*this, OpLoc,
+                                                          LHS, RHS, Opc);
+        if (IsEqualCall.isUsable())
+          return IsEqualCall;
+        // Otherwise, fall back to the normal warning in CheckCompareOperands.
+      }
     }
     ResultTy = CheckCompareOperands(LHS, RHS, OpLoc, Opc, false);
     break;