Fix #13812 value potentially truncated in ValueFlowAnalyzer::evaluteInt() (cppcheck-opensource#8482)

Author: chrchr-github

lib/vf_analyzers.cpp

@@ -676,7 +676,7 @@ struct ValueFlowAnalyzer : Analyzer {
     std::vector<MathLib::bigint> evaluateInt(const Token* tok, F getProgramMemory) const
     {
         if (const ValueFlow::Value* v = tok->getKnownValue(ValueFlow::Value::ValueType::INT))
-            return {static_cast<int>(v->intvalue)};
+            return {v->intvalue};
         std::vector<MathLib::bigint> result;
         ProgramMemory pm = getProgramMemory();
         if (Token::Match(tok, "&&|%oror%")) {
@@ -717,7 +717,7 @@ struct ValueFlowAnalyzer : Analyzer {
             ProgramMemory pm = pms.get(tok, ctx, getProgramState());
             MathLib::bigint out = 0;
             if (pm.getContainerEmptyValue(tok->exprId(), out))
-                return {static_cast<int>(out)};
+                return {out};
             return {};
         }
         return {};

test/testvalueflow.cpp

@@ -320,7 +320,7 @@ class TestValueFlow : public TestFixture {
     }
 
 #define testValueOfX(...) testValueOfX_(__FILE__, __LINE__, __VA_ARGS__)
-    bool testValueOfX_(const char* file, int line, const char code[], unsigned int linenr, int value, const Settings *s = nullptr) {
+    bool testValueOfX_(const char* file, int line, const char code[], unsigned int linenr, MathLib::bigint value, const Settings *s = nullptr) {
         const Settings *settings1 = s ? s : &settings;
 
         // Tokenize..
@@ -3973,6 +3973,14 @@ class TestValueFlow : public TestFixture {
                "    return x;\n"
                "}";
         ASSERT_EQUALS(true, testValueOfX(code, 4U, 246));
+
+        code = "int64_t f() {\n"
+               "    const int64_t val = 1LL << 33;\n"
+               "    int64_t x = val;\n"
+               "    x += val;\n"
+               "    return x;\n"
+               "}";
+        ASSERT_EQUALS(true, testValueOfX(code, 5U, 1LL << 34));
     }
 
     void valueFlowForwardCorrelatedVariables() {