Merge pull request #8 from dcleblanc/SafeNegate

Safe negate

SafeInt.hpp

@@ -3,7 +3,7 @@
 
 /*-----------------------------------------------------------------------------------------------------------
 SafeInt.hpp
-Version 3.0.20p
+Version 3.0.21p
 
 This header implements an integer handling class designed to catch
 unsafe integer operations
@@ -1024,6 +1024,17 @@ template < typename T > class NegationHelper <T, true> // Signed
         }
         E::SafeIntOnOverflow();
     }
+
+    _CONSTEXPR14 static bool Negative(T t, T& out)
+    {
+        // corner case
+        if (t != std::numeric_limits<T>::min())
+        {
+            out = -t;
+            return true;
+        }
+        return false;
+    }
 };
 
 template < typename T > class NegationHelper <T, false> // unsigned
@@ -1039,6 +1050,11 @@ template < typename T > class NegationHelper <T, false> // unsigned
         return (T)SignedNegation<std::int64_t>::Value(t);
     }
 
+    _CONSTEXPR14 static bool Negative(T t, T& /*out*/)
+    {
+        // This will only be used by the SafeNegation function
+        return false;
+    }
 };
 
 //core logic to determine casting behavior
@@ -5597,6 +5613,12 @@ _CONSTEXPR11 inline bool SafeSubtract( T t, U u, T& result ) SAFEINT_NOTHROW
     return SubtractionHelper< T, U, SubtractionMethod< T, U >::method >::Subtract( t, u, result );
 }
 
+template < typename T >
+_CONSTEXPR11 inline bool SafeNegation(T t, T& result) SAFEINT_NOTHROW
+{
+    return NegationHelper< T, std::numeric_limits<T>::is_signed>::Negative(t, result);
+}
+
 /*****************  end external functions ************************************/
 
 // Main SafeInt class

Test/ClangTest/.gitignore

@@ -1,2 +1,3 @@
 SafeIntTest
 CompileTest
+CompileTest14

Test/SubVerify.cpp

@@ -6954,4 +6954,66 @@ void SubVerify()
     SubVerifyInt8Int8();
 }
 
+}
+
+namespace negation_verify
+{
+    template < typename T >
+    void NegationVerifyT()
+    {
+        T minInt = std::numeric_limits<T>::min();
+        T test = 2;
+        bool result = false;
+        T out = 0;
+
+        try
+        {
+            out = -SafeInt< T >(minInt);
+        }
+        catch (...)
+        {
+            result = true;
+        }
+
+        if (result == false)
+            cerr << "Error in NegationVerifyT throw (1): ";
+
+        try
+        {
+            out = -SafeInt< T >(test);
+        }
+        catch (...)
+        {
+            result = false;
+        }
+
+        if (result == false)
+            cerr << "Error in NegationVerifyT throw (2): ";
+
+        // Now try the non-throwing version
+
+        result = SafeNegation(minInt, out);
+
+        if (result != false)
+            cerr << "Error in NegationVerifyT nothrow (1): ";
+
+        result = SafeNegation(test, out);
+
+        if (result == false)
+            cerr << "Error in NegationVerifyT nothrow (2): ";
+    }
+
+    void NegationVerifyAll()
+    {
+        NegationVerifyT< std::int8_t>();
+        NegationVerifyT< std::int16_t>();
+        NegationVerifyT< std::int32_t>();
+        NegationVerifyT< std::int64_t>();
+    }
+
+    void NegationVerify()
+    {
+        cout << "Verifying Negation:" << endl;
+        NegationVerifyAll();
+    }
 }

Test/TestMain.cpp

@@ -9,13 +9,13 @@
 
 int main(int, char**)
 {
-	cast_verify::CastVerify();
-	mult_verify::MultVerify();
-	div_verify::DivVerify();
-	sub_verify::SubVerify();
-	add_verify::AddVerify();
-	mod_verify::ModVerify();
-	incdec_verify::IncDecVerify();
-
-	return 0;
+    cast_verify::CastVerify();
+    mult_verify::MultVerify();
+    div_verify::DivVerify();
+    sub_verify::SubVerify();
+    add_verify::AddVerify();
+    mod_verify::ModVerify();
+    incdec_verify::IncDecVerify();
+    negation_verify::NegationVerify();
+    return 0;
 }

Test/TestMain.h

@@ -26,8 +26,8 @@ using std::dec;
 
 // Suppress warnings in test files, but not in source header
 #if SAFEINT_COMPILER == VISUAL_STUDIO_COMPILER
-
-#pragma warning(disable: 4838 4477 4310)
+// Disable Spectre mitigation warnings (5045)
+#pragma warning(disable: 4838 4477 4310 5045)
 #elif SAFEINT_COMPILER == CLANG_COMPILER 
 #pragma GCC diagnostic ignored "-Wc++11-narrowing"
 #pragma GCC diagnostic ignored "-Wformat"
@@ -52,4 +52,5 @@ namespace add_verify { void AddVerify(); }
 namespace mod_verify { void ModVerify(); }
 namespace incdec_verify { void IncDecVerify(); }
 namespace cast_verify { void CastVerify(); }
+namespace negation_verify { void NegationVerify(); }