[analyzer] Teach constraint managers about unsigned comparisons.

In C, comparisons between signed and unsigned numbers are always done in
unsigned-space. Thus, we should know that "i >= 0U" is always true, even
if 'i' is signed. Similarly, "u >= 0" is also always true, even though '0'
is signed.

Part of <rdar://problem/13239003> (false positives related to std::vector)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177806 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 3 deletions

diff --git a/include/clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h b/include/clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h
index 27f3677bba..9502900f7e 100644
--- a/include/clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h
+++ b/include/clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h
@@ -81,9 +81,12 @@ public:
 
   /// Tests whether a given value is losslessly representable using this type.
   ///
-  /// Note that signedness conversions will be rejected, even with the same bit
-  /// pattern. For example, -1s8 is not in range for 'unsigned char' (u8).
-  RangeTestResultKind testInRange(const llvm::APSInt &Val) const LLVM_READONLY;
+  /// \param Val The value to test.
+  /// \param AllowMixedSign Whether or not to allow signedness conversions.
+  ///                       This determines whether -1s8 is considered in range
+  ///                       for 'unsigned char' (u8).
+  RangeTestResultKind testInRange(const llvm::APSInt &Val,
+                                  bool AllowMixedSign) const LLVM_READONLY;
   
   bool operator==(const APSIntType &Other) const {
     return BitWidth == Other.BitWidth && IsUnsigned == Other.IsUnsigned;