Partial fix for #9078 FN compareValueOutOfTypeRangeError (x <= UINT32_MAX) (cppcheck-opensource#8379)

Author: chrchr-github

lib/checkcondition.cpp

@@ -1975,8 +1975,6 @@ void CheckCondition::checkCompareValueOutOfTypeRange()
                     continue;
                 if (valueTok->getKnownIntValue() < 0 && valueTok->valueType() && valueTok->valueType()->sign != ValueType::Sign::SIGNED)
                     continue;
-                if (valueTok->valueType() && valueTok->valueType()->isTypeEqual(typeTok->valueType()))
-                    continue;
                 std::uint8_t bits = 0;
                 switch (typeTok->valueType()->type) {
                 case ValueType::Type::BOOL:
@@ -2015,6 +2013,8 @@ void CheckCondition::checkCompareValueOutOfTypeRange()
 
                 bool result{};
                 const auto kiv = valueTok->getKnownIntValue();
+                if (kiv == 0)
+                    continue; // prevent overlap with TestOther::unsignedPositive/unsignedLessThanZero
                 if (tok->str() == "==")
                     result = false;
                 else if (tok->str() == "!=")

lib/vf_settokenvalue.cpp

@@ -72,7 +72,7 @@ namespace ValueFlow
             return value;
         if (!parent->isBinaryOp())
             return value;
-        if (!parent->isConstOp())
+        if (!parent->isConstOp() && !parent->isAssignmentOp())
             return value;
         if (!astIsIntegral(parent->astOperand1(), false))
             return value;
@@ -88,7 +88,7 @@ namespace ValueFlow
         ValueType::Sign sign = ValueType::Sign::UNSIGNED;
         if (n1 < n2)
             sign = vt2->sign;
-        else if (n1 > n2)
+        else // (n1 >= n2)
             sign = vt1->sign;
         Value v = castValue(value, sign, std::max(n1, n2) * 8);
         v.wideintvalue = value.intvalue;

test/testcondition.cpp

@@ -6324,28 +6324,24 @@ class TestCondition : public TestFixture {
 
         check("void f(const unsigned char u) {\n"
               "    if (u >  0) {}\n"
-              "    if (u <  0) {}\n" // warn
-              "    if (u >= 0) {}\n" // warn
+              "    if (u <  0) {}\n"
+              "    if (u >= 0) {}\n"
               "    if (u <= 0) {}\n"
               "    if (u >  255) {}\n" // warn
               "    if (u <  255) {}\n"
               "    if (u >= 255) {}\n"
               "    if (u <= 255) {}\n" // warn
               "    if (0   <  u) {}\n"
-              "    if (0   >  u) {}\n" // warn
-              "    if (0   <= u) {}\n" // warn
+              "    if (0   >  u) {}\n"
+              "    if (0   <= u) {}\n"
               "    if (0   >= u) {}\n"
               "    if (255 <  u) {}\n" // warn
               "    if (255 >  u) {}\n"
               "    if (255 <= u) {}\n"
               "    if (255 >= u) {}\n" // warn
               "}\n", settingsUnix64);
-        ASSERT_EQUALS("[test.cpp:3:14]: (style) Comparing expression of type 'const unsigned char' against value 0. Condition is always false. [compareValueOutOfTypeRangeError]\n"
-                      "[test.cpp:4:14]: (style) Comparing expression of type 'const unsigned char' against value 0. Condition is always true. [compareValueOutOfTypeRangeError]\n"
-                      "[test.cpp:6:14]: (style) Comparing expression of type 'const unsigned char' against value 255. Condition is always false. [compareValueOutOfTypeRangeError]\n"
+        ASSERT_EQUALS("[test.cpp:6:14]: (style) Comparing expression of type 'const unsigned char' against value 255. Condition is always false. [compareValueOutOfTypeRangeError]\n"
                       "[test.cpp:9:14]: (style) Comparing expression of type 'const unsigned char' against value 255. Condition is always true. [compareValueOutOfTypeRangeError]\n"
-                      "[test.cpp:11:9]: (style) Comparing expression of type 'const unsigned char' against value 0. Condition is always false. [compareValueOutOfTypeRangeError]\n"
-                      "[test.cpp:12:9]: (style) Comparing expression of type 'const unsigned char' against value 0. Condition is always true. [compareValueOutOfTypeRangeError]\n"
                       "[test.cpp:14:9]: (style) Comparing expression of type 'const unsigned char' against value 255. Condition is always false. [compareValueOutOfTypeRangeError]\n"
                       "[test.cpp:17:9]: (style) Comparing expression of type 'const unsigned char' against value 255. Condition is always true. [compareValueOutOfTypeRangeError]\n",
                       errout_str());
@@ -6355,6 +6351,15 @@ class TestCondition : public TestFixture {
               "}\n", settingsUnix64);
         ASSERT_EQUALS("[test.cpp:2:14]: (style) Comparing expression of type 'bool' against value 2. Condition is always true. [compareValueOutOfTypeRangeError]\n",
                       errout_str());
+
+        check("void f(const std::uint32_t& u) {\n" // #9078
+              "    if (u >= UINT32_MAX) {}\n"
+              "    if (u <= UINT32_MAX) {}\n"
+              "    if (u > UINT32_MAX) {}\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3:14]: (style) Comparing expression of type 'const unsigned int &' against value 4294967295. Condition is always true. [compareValueOutOfTypeRangeError]\n"
+                      "[test.cpp:4:13]: (style) Comparing expression of type 'const unsigned int &' against value 4294967295. Condition is always false. [compareValueOutOfTypeRangeError]\n",
+                      errout_str());
     }
 
     void knownConditionCast() {

test/testother.cpp

@@ -9313,6 +9313,24 @@ class TestOther : public TestFixture {
               "    for (unsigned p = 0; p < (sizeof(a) / sizeof((a)[0])); ++p) {}\n"
               "}");
         ASSERT_EQUALS("", errout_str());
+
+        check("void f(const unsigned char u) {\n"
+              "    if (u >  0) {}\n"
+              "    if (u <  0) {}\n"
+              "    if (u >= 0) {}\n"
+              "    if (u <= 0) {}\n"
+              "    if (0 <  u) {}\n"
+              "    if (0 >  u) {}\n"
+              "    if (0 <= u) {}\n"
+              "    if (0 >= u) {}\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:3:11]: (style) Checking if unsigned expression 'u' is less than zero. [unsignedLessThanZero]\n"
+                      "[test.cpp:4:11]: (style) Unsigned expression 'u' can't be negative so it is unnecessary to test it. [unsignedPositive]\n"
+                      "[test.cpp:5:11]: (style) Checking if unsigned expression 'u' is less than zero. [unsignedLessThanZero]\n"
+                      "[test.cpp:7:11]: (style) Checking if unsigned expression 'u' is less than zero. [unsignedLessThanZero]\n"
+                      "[test.cpp:8:11]: (style) Unsigned expression 'u' can't be negative so it is unnecessary to test it. [unsignedPositive]\n"
+                      "[test.cpp:9:11]: (style) Checking if unsigned expression 'u' is less than zero. [unsignedLessThanZero]\n",
+                      errout_str());
     }
 
     void checkSignOfPointer() {

test/testvalueflow.cpp

@@ -3112,6 +3112,12 @@ class TestValueFlow : public TestFixture {
                "    return x;\n"
                "}\n";
         ASSERT_EQUALS(false, testValueOfXKnown(code, 9U, 1));
+
+        code = "int32_t f() {\n"
+               "    const int32_t x = 0xffffffff;\n"
+               "    return x;\n"
+               "}\n";
+        ASSERT_EQUALS(true, testValueOfXKnown(code, 3U, -1));
     }
 
     void valueFlowAfterSwap()