From 847bb44bddb25ad054bca5303972e313b3e220cb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Mon, 16 Jun 2014 16:39:41 +0200
Subject: [PATCH] ValueFlow: Improved analysis after condition when ! operator
 is used

---
 lib/valueflow.cpp      | 56 +++++++++++++++++++++++++++++++-----------
 test/testvalueflow.cpp | 11 ++++++++-
 2 files changed, 51 insertions(+), 16 deletions(-)

diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index 5b9635fa2..7d0da70b6 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -753,35 +753,61 @@ 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
-        if (!tok->isComparisonOp() || !Token::Match(tok,"==|!=|>=|<="))
-            continue;
-
-        if (!tok->astOperand1() || !tok->astOperand2())
-            continue;
-
         const Token *vartok, *numtok;
-        if (tok->astOperand1()->isName()) {
+
+        // Comparison
+        if (Token::Match(tok,"==|!=|>=|<=")) {
+            if (!tok->astOperand1() || !tok->astOperand2())
+                continue;
+            if (tok->astOperand1()->isName()) {
+                vartok = tok->astOperand1();
+                numtok = tok->astOperand2();
+            } else {
+                vartok = tok->astOperand2();
+                numtok = tok->astOperand1();
+            }
+            if (!vartok->isName() || !numtok->isNumber())
+                continue;
+        } else if (tok->str() == "!") {
             vartok = tok->astOperand1();
-            numtok = tok->astOperand2();
+            numtok = nullptr;
+            if (!vartok || !vartok->isName())
+                continue;
         } else {
-            vartok = tok->astOperand2();
-            numtok = tok->astOperand1();
-        }
-        if (!vartok->isName() || !numtok->isNumber())
             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);
diff --git a/test/testvalueflow.cpp b/test/testvalueflow.cpp
index f773c2389..9b7008954 100644
--- a/test/testvalueflow.cpp
+++ b/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() {