Fixed #6383 (FP shiftNegative - value converted to unsigned in function argument)

Author: danmar

lib/checkother.cpp

@@ -2178,6 +2178,11 @@ void CheckOther::redundantCopyError(const Token *tok,const std::string& varname)
 // Checking for shift by negative values
 //---------------------------------------------------------------------------
 
+static bool isNegative(const Token *tok, const Settings *settings)
+{
+    return tok->valueType() && tok->valueType()->sign == ValueType::SIGNED && tok->getValueLE(-1LL, settings);
+}
+
 void CheckOther::checkNegativeBitwiseShift()
 {
     for (const Token* tok = _tokenizer->tokens(); tok; tok = tok->next()) {
@@ -2213,9 +2218,9 @@ void CheckOther::checkNegativeBitwiseShift()
             continue;
 
         // Get negative rhs value. preferably a value which doesn't have 'condition'.
-        if (tok->astOperand1()->getValueLE(-1LL, _settings))
+        if (isNegative(tok->astOperand1(), _settings))
             negativeBitwiseShiftError(tok, 1);
-        else if (tok->astOperand2()->getValueLE(-1LL, _settings))
+        else if (isNegative(tok->astOperand2(), _settings))
             negativeBitwiseShiftError(tok, 2);
     }
 }

test/testother.cpp

@@ -4788,6 +4788,10 @@ class TestOther : public TestFixture {
         // Negative LHS
         check("const int x = -1 >> 2;");
         ASSERT_EQUALS("[test.cpp:1]: (error) Shifting a negative value is undefined behaviour\n", errout.str());
+
+        // #6383 - unsigned type
+        check("const int x = (unsigned int)(-1) >> 2;");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void incompleteArrayFill() {