Take into account the zero sign bit for positive numbers when computing the bit

width of an enum with negative values in IntRange.  Include a test for
-Wtautological-constant-out-of-range-compare where this had manifested.

llvm-svn: 168126

1 files changed, 5 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 05fa2a06637..8e0a983d127 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -3922,7 +3922,11 @@ struct IntRange {
       unsigned NumPositive = Enum->getNumPositiveBits();
       unsigned NumNegative = Enum->getNumNegativeBits();
 
-      return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0);
+      if (NumNegative == 0)
+        return IntRange(NumPositive, true/*NonNegative*/);
+      else
+        return IntRange(std::max(NumPositive + 1, NumNegative),
+                        false/*NonNegative*/);
     }
 
     const BuiltinType *BT = cast<BuiltinType>(T);