ValueFlow: Improved analysis after condition when ! operator is used

lib/valueflow.cpp

@@ -753,14 +753,12 @@ static void valueFlowAfterAssign(TokenList *tokenlist, ErrorLogger *errorLogger,
 static void valueFlowAfterCondition(TokenList *tokenlist, ErrorLogger *errorLogger, const Settings *settings)
 {
     for (Token *tok = tokenlist->front(); tok; tok = tok->next()) {
-        // Comparison
+        const Token *vartok, *numtok;
-        if (!tok->isComparisonOp() || !Token::Match(tok,"==|!=|>=|<="))
-            continue;
 
+        // Comparison
+        if (Token::Match(tok,"==|!=|>=|<=")) {
             if (!tok->astOperand1() || !tok->astOperand2())
                 continue;
-
-        const Token *vartok, *numtok;
             if (tok->astOperand1()->isName()) {
                 vartok = tok->astOperand1();
                 numtok = tok->astOperand2();
@@ -770,18 +768,46 @@ static void valueFlowAfterCondition(TokenList *tokenlist, ErrorLogger *errorLogg
             }
             if (!vartok->isName() || !numtok->isNumber())
                 continue;
+        } else if (tok->str() == "!") {
+            vartok = tok->astOperand1();
+            numtok = nullptr;
+            if (!vartok || !vartok->isName())
+                continue;
+        } else {
+            continue;
+        }
         const unsigned int varid = vartok->varId();
         if (varid == 0U)
             continue;
         const Variable *var = vartok->variable();
         if (!var || !(var->isLocal() || var->isArgument()))
             continue;
-        std::list<ValueFlow::Value> values = numtok->values;
+        std::list<ValueFlow::Value> values;
+        values.push_back(ValueFlow::Value(tok, numtok ? MathLib::toLongNumber(numtok->str()) : 0LL));
 
         const Token *top = tok->astTop();
         if (top && Token::simpleMatch(top->previous(), "if (")) {
+            // does condition reassign variable?
+            std::stack<const Token *> tokens;
+            tokens.push(top);
+            while (!tokens.empty()) {
+                const Token *tok2 = tokens.top();
+                tokens.pop();
+                if (!tok2)
+                    continue;
+                tokens.push(tok2->astOperand1());
+                tokens.push(tok2->astOperand2());
+                if (tok2->str() == "=" && Token::Match(tok2->astOperand1(), "%varid%", varid))
+                    break;
+            }
+            if (!tokens.empty()) {
+                if (settings->debugwarnings)
+                    bailout(tokenlist, errorLogger, tok, "assignment in condition");
+                continue;
+            }
+
             Token *startToken = nullptr;
-            if (Token::Match(tok, "==|>=|<=") && Token::simpleMatch(top->link(), ") {"))
+            if (Token::Match(tok, "==|>=|<=|!") && Token::simpleMatch(top->link(), ") {"))
                 startToken = top->link()->next();
             else if (tok->str() == "!=" && Token::simpleMatch(top->link()->linkAt(1), "} else {"))
                 startToken = top->link()->linkAt(1)->tokAt(2);

test/testvalueflow.cpp

@@ -488,7 +488,8 @@ private:
                 "    if (abc) {}\n"
                 "}\n");
         ASSERT_EQUALS("[test.cpp:2]: (debug) ValueFlow bailout: assignment of abc\n"
-                      "[test.cpp:8]: (debug) ValueFlow bailout: variable abc stopping on goto label\n",
+                      "[test.cpp:8]: (debug) ValueFlow bailout: variable abc stopping on goto label\n"
+                      "[test.cpp:3]: (debug) ValueFlow bailout: variable abc. noreturn conditional scope.\n",
                       errout.str());
     }
 
@@ -750,6 +751,14 @@ private:
                "    else a = x;\n"
                "}";
         ASSERT_EQUALS(true, testValueOfX(code, 3U, 123));
+
+        // !
+        code = "void f(int x) {\n"
+               "    if (!x) { a = x; }\n"
+               "    else a = x;\n"
+               "}";
+        ASSERT_EQUALS(true, testValueOfX(code, 2U, 0));
+
     }
 
     void valueFlowBitAnd() {