ValueFlow: Evaluate if statement for function returns (#4908)

lib/cppcheck.cpp

@@ -943,6 +943,7 @@ unsigned int CppCheck::checkFile(const std::string& filename, const std::string
                     checkUnusedFunctions.parseTokens(tokenizer, filename.c_str(), &mSettings);
 
                 // handling of "simple" rules has been removed.
+                // cppcheck-suppress knownConditionTrueFalse
                 if (mSimplify && hasRule("simple"))
                     throw InternalError(nullptr, "Handling of \"simple\" rules has been removed in Cppcheck. Use --addon instead.");
 

lib/programmemory.cpp

@@ -233,6 +233,20 @@ static bool frontIs(const std::vector<MathLib::bigint>& v, bool i)
     return !i;
 }
 
+static bool isTrue(const ValueFlow::Value& v)
+{
+    if (v.isImpossible())
+        return v.intvalue == 0;
+    return v.intvalue != 0;
+}
+
+static bool isFalse(const ValueFlow::Value& v)
+{
+    if (v.isImpossible())
+        return false;
+    return v.intvalue == 0;
+}
+
 // If the scope is a non-range for loop
 static bool isBasicForLoop(const Token* tok)
 {
@@ -543,6 +557,7 @@ static bool isIntegralValue(const ValueFlow::Value& value)
 static ValueFlow::Value evaluate(const std::string& op, const ValueFlow::Value& lhs, const ValueFlow::Value& rhs)
 {
     ValueFlow::Value result;
+    combineValueProperties(lhs, rhs, result);
     if (lhs.isImpossible() && rhs.isImpossible())
         return ValueFlow::Value::unknown();
     if (lhs.isImpossible() || rhs.isImpossible()) {
@@ -593,11 +608,16 @@ static ValueFlow::Value evaluate(const std::string& op, const ValueFlow::Value&
     result.intvalue = calculate(op, lhs.intvalue, rhs.intvalue, &error);
     if (error)
         return ValueFlow::Value::unknown();
-    if (result.isImpossible()) {
-        if ((result.intvalue == 0 && op == "!=") || (result.intvalue != 0 && op == "==")) {
-            result.setPossible();
-            result.intvalue = !result.intvalue;
+    if (result.isImpossible() && op == "!=") {
+        if (isTrue(result)) {
+            result.intvalue = 1;
+        } else if (isFalse(result)) {
+            result.intvalue = 0;
+        } else {
+            return ValueFlow::Value::unknown();
         }
+        result.setPossible();
+        result.bound = ValueFlow::Value::Bound::Point;
     }
     return result;
 }
@@ -1152,7 +1172,10 @@ static ValueFlow::Value executeImpl(const Token* expr, ProgramMemory& pm, const
     } else if (expr->isNumber()) {
         if (MathLib::isFloat(expr->str()))
             return unknown;
-        return ValueFlow::Value{MathLib::toLongNumber(expr->str())};
+        MathLib::bigint i = MathLib::toLongNumber(expr->str());
+        if (i < 0 && astIsUnsigned(expr))
+            return unknown;
+        return ValueFlow::Value{i};
     } else if (expr->isBoolean()) {
         return ValueFlow::Value{ expr->str() == "true" };
     } else if (Token::Match(expr->tokAt(-2), ". %name% (") && astIsContainer(expr->tokAt(-2)->astOperand1())) {
@@ -1197,16 +1220,20 @@ static ValueFlow::Value executeImpl(const Token* expr, ProgramMemory& pm, const
         ValueFlow::Value lhs = execute(expr->astOperand1(), pm);
         if (!lhs.isIntValue())
             return unknown;
-        if (lhs.intvalue == 0)
+        if (isFalse(lhs))
             return lhs;
-        return execute(expr->astOperand2(), pm);
+        if (isTrue(lhs))
+            return execute(expr->astOperand2(), pm);
+        return unknown;
     } else if (expr->str() == "||" && expr->astOperand1() && expr->astOperand2()) {
         ValueFlow::Value lhs = execute(expr->astOperand1(), pm);
-        if (!lhs.isIntValue())
+        if (!lhs.isIntValue() || lhs.isImpossible())
             return unknown;
-        if (lhs.intvalue != 0)
+        if (isTrue(lhs))
             return lhs;
-        return execute(expr->astOperand2(), pm);
+        if (isFalse(lhs))
+            return execute(expr->astOperand2(), pm);
+        return unknown;
     } else if (expr->str() == "," && expr->astOperand1() && expr->astOperand2()) {
         execute(expr->astOperand1(), pm);
         return execute(expr->astOperand2(), pm);
@@ -1251,31 +1278,42 @@ static ValueFlow::Value executeImpl(const Token* expr, ProgramMemory& pm, const
     } else if (Token::Match(expr, "%cop%") && expr->astOperand1() && expr->astOperand2()) {
         ValueFlow::Value lhs = execute(expr->astOperand1(), pm);
         ValueFlow::Value rhs = execute(expr->astOperand2(), pm);
+        ValueFlow::Value r = unknown;
         if (!lhs.isUninitValue() && !rhs.isUninitValue())
-            return evaluate(expr->str(), lhs, rhs);
-        if (expr->isComparisonOp()) {
+            r = evaluate(expr->str(), lhs, rhs);
+        if (expr->isComparisonOp() && (r.isUninitValue() || r.isImpossible())) {
             if (rhs.isIntValue()) {
                 std::vector<ValueFlow::Value> result =
                     infer(ValueFlow::makeIntegralInferModel(), expr->str(), expr->astOperand1()->values(), {rhs});
-                if (result.empty() || !result.front().isKnown())
-                    return unknown;
-                return result.front();
-            } else if (lhs.isIntValue()) {
+                if (!result.empty() && result.front().isKnown())
+                    return result.front();
+            }
+            if (lhs.isIntValue()) {
                 std::vector<ValueFlow::Value> result =
                     infer(ValueFlow::makeIntegralInferModel(), expr->str(), {lhs}, expr->astOperand2()->values());
-                if (result.empty() || !result.front().isKnown())
-                    return unknown;
-                return result.front();
+                if (!result.empty() && result.front().isKnown())
+                    return result.front();
             }
+            return unknown;
         }
+        return r;
     }
     // Unary ops
     else if (Token::Match(expr, "!|+|-") && expr->astOperand1() && !expr->astOperand2()) {
         ValueFlow::Value lhs = execute(expr->astOperand1(), pm);
         if (!lhs.isIntValue())
             return unknown;
-        if (expr->str() == "!")
-            lhs.intvalue = !lhs.intvalue;
+        if (expr->str() == "!") {
+            if (isTrue(lhs)) {
+                lhs.intvalue = 0;
+            } else if (isFalse(lhs)) {
+                lhs.intvalue = 1;
+            } else {
+                return unknown;
+            }
+            lhs.setPossible();
+            lhs.bound = ValueFlow::Value::Bound::Point;
+        }
         if (expr->str() == "-")
             lhs.intvalue = -lhs.intvalue;
         return lhs;
@@ -1284,10 +1322,12 @@ static ValueFlow::Value executeImpl(const Token* expr, ProgramMemory& pm, const
         if (!cond.isIntValue())
             return unknown;
         const Token* child = expr->astOperand2();
-        if (cond.intvalue == 0)
+        if (isFalse(cond))
             return execute(child->astOperand2(), pm);
-        else
+        else if (isTrue(cond))
             return execute(child->astOperand1(), pm);
+        else
+            return unknown;
     } else if (expr->str() == "(" && expr->isCast()) {
         if (Token::simpleMatch(expr->previous(), ">") && expr->previous()->link())
             return execute(expr->astOperand2(), pm);
@@ -1349,6 +1389,26 @@ static ValueFlow::Value executeImpl(const Token* expr, ProgramMemory& pm, const
     return unknown;
 }
 
+static const ValueFlow::Value* getImpossibleValue(const Token* tok)
+{
+    if (!tok)
+        return nullptr;
+    std::vector<const ValueFlow::Value*> values;
+    for (const ValueFlow::Value& v : tok->values()) {
+        if (!v.isImpossible())
+            continue;
+        if (v.isContainerSizeValue() || v.isIntValue()) {
+            values.push_back(std::addressof(v));
+        }
+    }
+    auto it = std::max_element(values.begin(), values.end(), [](const ValueFlow::Value* x, const ValueFlow::Value* y) {
+        return x->intvalue < y->intvalue;
+    });
+    if (it == values.end())
+        return nullptr;
+    return *it;
+}
+
 static ValueFlow::Value execute(const Token* expr, ProgramMemory& pm, const Settings* settings)
 {
     ValueFlow::Value v = executeImpl(expr, pm, settings);
@@ -1358,9 +1418,63 @@ static ValueFlow::Value execute(const Token* expr, ProgramMemory& pm, const Sett
         return v;
     if (pm.hasValue(expr->exprId()))
         return pm.at(expr->exprId());
+    if (const ValueFlow::Value* value = getImpossibleValue(expr))
+        return *value;
     return v;
 }
 
+std::vector<ValueFlow::Value> execute(const Scope* scope, ProgramMemory& pm, const Settings* settings)
+{
+    static const std::vector<ValueFlow::Value> unknown = {ValueFlow::Value::unknown()};
+    if (!scope)
+        return unknown;
+    if (!scope->bodyStart)
+        return unknown;
+    for (const Token* tok = scope->bodyStart->next(); precedes(tok, scope->bodyEnd); tok = tok->next()) {
+        const Token* top = tok->astTop();
+        if (!top)
+            return unknown;
+
+        if (Token::simpleMatch(top, "return") && top->astOperand1()) {
+            return {execute(top->astOperand1(), pm, settings)};
+        } else if (Token::Match(top, "%op%")) {
+            if (execute(top, pm, settings).isUninitValue())
+                return unknown;
+            const Token* next = nextAfterAstRightmostLeaf(top);
+            if (!next)
+                return unknown;
+            tok = next;
+        } else if (Token::simpleMatch(top->previous(), "if (")) {
+            const Token* condTok = top->astOperand2();
+            ValueFlow::Value v = execute(condTok, pm, settings);
+            if (!v.isIntValue())
+                return unknown;
+            const Token* thenStart = top->link()->next();
+            const Token* next = thenStart->link();
+            const Token* elseStart = nullptr;
+            if (Token::simpleMatch(thenStart->link(), "} else {")) {
+                elseStart = thenStart->link()->tokAt(2);
+                next = elseStart->link();
+            }
+            std::vector<ValueFlow::Value> result;
+            if (isTrue(v)) {
+                result = execute(thenStart->scope(), pm, settings);
+            } else if (isFalse(v)) {
+                if (elseStart)
+                    result = execute(elseStart->scope(), pm, settings);
+            } else {
+                return unknown;
+            }
+            if (!result.empty())
+                return result;
+            tok = next;
+        } else {
+            return unknown;
+        }
+    }
+    return {};
+}
+
 ValueFlow::Value evaluateLibraryFunction(const std::unordered_map<nonneg int, ValueFlow::Value>& args,
                                          const std::string& returnValue,
                                          const Settings* settings)

lib/programmemory.h

@@ -30,6 +30,7 @@
 #include <unordered_map>
 #include <utility>
 
+class Scope;
 class Token;
 class Settings;
 
@@ -142,6 +143,8 @@ struct ProgramMemoryState {
     ProgramMemory get(const Token* tok, const Token* ctx, const ProgramMemory::Map& vars) const;
 };
 
+std::vector<ValueFlow::Value> execute(const Scope* scope, ProgramMemory& pm, const Settings* settings);
+
 void execute(const Token* expr,
              ProgramMemory& programMemory,
              MathLib::bigint* result,

lib/symboldatabase.cpp

@@ -3022,6 +3022,8 @@ std::vector<const Token*> Function::findReturns(const Function* f)
     const Scope* scope = f->functionScope;
     if (!scope)
         return result;
+    if (!scope->bodyStart)
+        return result;
     for (const Token* tok = scope->bodyStart->next(); tok && tok != scope->bodyEnd; tok = tok->next()) {
         if (tok->str() == "{" && tok->scope() &&
             (tok->scope()->type == Scope::eLambda || tok->scope()->type == Scope::eClass)) {

lib/valueflow.cpp

@@ -7539,9 +7539,45 @@ static void valueFlowFunctionDefaultParameter(TokenList* tokenlist, SymbolDataba
     }
 }
 
-static bool isKnown(const Token * tok)
+static const ValueFlow::Value* getKnownValueFromToken(const Token* tok)
 {
-    return tok && tok->hasKnownIntValue();
+    if (!tok)
+        return nullptr;
+    auto it = std::find_if(tok->values().begin(), tok->values().end(), [&](const ValueFlow::Value& v) {
+        return (v.isIntValue() || v.isContainerSizeValue() || v.isFloatValue()) && v.isKnown();
+    });
+    if (it == tok->values().end())
+        return nullptr;
+    return std::addressof(*it);
+}
+
+static const ValueFlow::Value* getKnownValueFromTokens(const std::vector<const Token*>& toks)
+{
+    if (toks.empty())
+        return nullptr;
+    const ValueFlow::Value* result = getKnownValueFromToken(toks.front());
+    if (!result)
+        return nullptr;
+    if (!std::all_of(std::next(toks.begin()), toks.end(), [&](const Token* tok) {
+        return std::any_of(tok->values().begin(), tok->values().end(), [&](const ValueFlow::Value& v) {
+            return v.equalValue(*result) && v.valueKind == result->valueKind;
+        });
+    }))
+        return nullptr;
+    return result;
+}
+
+static void setFunctionReturnValue(const Function* f, Token* tok, ValueFlow::Value v, const Settings* settings)
+{
+    if (f->hasVirtualSpecifier()) {
+        if (v.isImpossible())
+            return;
+        v.setPossible();
+    } else if (!v.isImpossible()) {
+        v.setKnown();
+    }
+    v.errorPath.emplace_back(tok, "Calling function '" + f->name() + "' returns " + v.toString());
+    setTokenValue(tok, std::move(v), settings);
 }
 
 static void valueFlowFunctionReturn(TokenList *tokenlist, ErrorLogger *errorLogger, const Settings* settings)
@@ -7564,34 +7600,20 @@ static void valueFlowFunctionReturn(TokenList *tokenlist, ErrorLogger *errorLogg
         if (tok->hasKnownValue())
             continue;
 
-        // Arguments..
-        std::vector<MathLib::bigint> parvalues;
-        if (tok->astOperand2()) {
-            const Token *partok = tok->astOperand2();
-            while (partok && partok->str() == "," && isKnown(partok->astOperand2()))
-                partok = partok->astOperand1();
-            if (!isKnown(partok))
-                continue;
-            parvalues.push_back(partok->values().front().intvalue);
-            partok = partok->astParent();
-            while (partok && partok->str() == ",") {
-                parvalues.push_back(partok->astOperand2()->values().front().intvalue);
-                partok = partok->astParent();
-            }
-            if (partok != tok)
-                continue;
-        }
+        std::vector<const Token*> returns = Function::findReturns(function);
+        if (returns.empty())
+            continue;
 
-        // Get scope and args of function
-        const Scope * const functionScope = function->functionScope;
-        if (!functionScope || !Token::simpleMatch(functionScope->bodyStart, "{ return")) {
-            if (functionScope && settings->debugwarnings && Token::findsimplematch(functionScope->bodyStart, "return", functionScope->bodyEnd))
-                bailout(tokenlist, errorLogger, tok, "function return; nontrivial function body");
+        if (const ValueFlow::Value* v = getKnownValueFromTokens(returns)) {
+            setFunctionReturnValue(function, tok, *v, settings);
             continue;
         }
 
+        // Arguments..
+        std::vector<const Token*> arguments = getArguments(tok);
+
         ProgramMemory programMemory;
-        for (std::size_t i = 0; i < parvalues.size(); ++i) {
+        for (std::size_t i = 0; i < arguments.size(); ++i) {
             const Variable * const arg = function->getArgumentVar(i);
             if (!arg) {
                 if (settings->debugwarnings)
@@ -7599,25 +7621,18 @@ static void valueFlowFunctionReturn(TokenList *tokenlist, ErrorLogger *errorLogg
                 programMemory.clear();
                 break;
             }
-            programMemory.setIntValue(arg->nameToken(), parvalues[i]);
+            const ValueFlow::Value* v = getKnownValueFromToken(arguments[i]);
+            if (!v)
+                continue;
+            programMemory.setValue(arg->nameToken(), *v);
         }
-        if (programMemory.empty() && !parvalues.empty())
+        if (programMemory.empty() && !arguments.empty())
             continue;
-
-        // Determine return value of subfunction..
-        MathLib::bigint result = 0;
-        bool error = false;
-        execute(functionScope->bodyStart->next()->astOperand1(),
-                programMemory,
-                &result,
-                &error);
-        if (!error) {
-            ValueFlow::Value v(result);
-            if (function->hasVirtualSpecifier())
-                v.setPossible();
-            else
-                v.setKnown();
-            setTokenValue(tok, std::move(v), settings);
+        std::vector<ValueFlow::Value> values = execute(function->functionScope, programMemory, settings);
+        for (const ValueFlow::Value& v : values) {
+            if (v.isUninitValue())
+                continue;
+            setFunctionReturnValue(function, tok, v, settings);
         }
     }
 }

test/testsimplifytypedef.cpp

@@ -1207,9 +1207,7 @@ private:
                                 "}";
 
         ASSERT_EQUALS(expected, tok(code, false));
-        ASSERT_EQUALS_WITHOUT_LINENUMBERS(
-            "[test.cpp:31]: (debug) valueflow.cpp:3109:valueFlowFunctionReturn bailout: function return; nontrivial function body\n",
-            errout.str());
+        ASSERT_EQUALS_WITHOUT_LINENUMBERS("", errout.str());
     }
 
     void simplifyTypedef36() {

test/testuninitvar.cpp

@@ -66,6 +66,7 @@ private:
         TEST_CASE(uninitvar2_func);     // function calls
         TEST_CASE(uninitvar2_value);    // value flow
         TEST_CASE(valueFlowUninit2_value);
+        TEST_CASE(valueFlowUninit_uninitvar2);
         TEST_CASE(uninitStructMember);  // struct members
         TEST_CASE(uninitvar2_while);
         TEST_CASE(uninitvar2_4494);      // #4494
@@ -3636,6 +3637,545 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void valueFlowUninit_uninitvar2()
+    {
+        // using uninit var
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    x++;\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: x\n", errout.str());
+
+        // extracttests.start: char str[10];
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    str[x] = 0;\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: x\n", errout.str());
+
+        valueFlowUninit("void f() {\n" // #7736
+                        "    int buf[12];\n"
+                        "    printf (\"%d\", buf[0] );\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: buf\n", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    int y = x & 3;\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: x\n", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    int y = 3 & x;\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: x\n", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    x = 3 + x;\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: x\n", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    x = x;\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: x\n", errout.str());
+
+        // extracttests.start: struct ABC {int a;};
+        valueFlowUninit("void f() {\n"
+                        "    struct ABC *abc;\n"
+                        "    abc->a = 0;\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: abc\n", errout.str());
+
+        valueFlowUninit("int f() {\n"
+                        "    static int x;\n"
+                        "    return ++x;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("int f() {\n"
+                        "    extern int x;\n"
+                        "    return ++x;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n" // #3926 - weird cast.
+                        "    int x;\n"
+                        "    *(((char *)&x) + 0) = 0;\n"
+                        "}",
+                        "test.c");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n" // #4737 - weird cast.
+                        "    int x;\n"
+                        "    do_something(&((char*)&x)[0], 1);\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    char *p = (char*)&x + 1;\n"
+                        "}",
+                        "test.cpp");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int i;\n"
+                        "    i=f(), i!=2;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        // using uninit var in condition
+        valueFlowUninit("void f(void) {\n"
+                        "    int x;\n"
+                        "    if (x) { }\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: x\n", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    if (1 == (3 & x)) { }\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: x\n", errout.str());
+
+        // ?:
+        valueFlowUninit("int f(int *ptr) {\n"
+                        "    int a;\n"
+                        "    int *p = ptr ? ptr : &a;\n"
+                        "}");
+        TODO_ASSERT_EQUALS("", "[test.cpp:3]: (error) Uninitialized variable: &a\n", errout.str());
+
+        valueFlowUninit("int f(int a) {\n"
+                        "    int x;\n"
+                        "    if (a==3) { x=2; }\n"
+                        "    y = (a==3) ? x : a;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        // = ({ .. })
+        valueFlowUninit("void f() {\n"
+                        "    int x = ({ 1 + 2; });\n"
+                        "    int y = 1 + (x ? y : y);\n"
+                        "}");
+        TODO_ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: y\n", "", errout.str());
+
+        // >> => initialization / usage
+        {
+            const char code[] = "void f() {\n"
+                                "    int x;\n"
+                                "    if (i >> x) { }\n"
+                                "}";
+            valueFlowUninit(code, "test.cpp");
+            ASSERT_EQUALS("", errout.str());
+
+            valueFlowUninit(code, "test.c");
+            ASSERT_EQUALS("[test.c:3]: (error) Uninitialized variable: x\n", errout.str());
+        }
+
+        valueFlowUninit("void f() {\n"
+                        "    int i, i2;\n"
+                        "    strm >> i >> i2;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        // unconditional initialization
+        valueFlowUninit("int f() {\n"
+                        "    int ret;\n"
+                        "    if (a) { ret = 1; }\n"
+                        "    else { {} ret = 2; }\n"
+                        "    return ret;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("int f() {\n"
+                        "    int ret;\n"
+                        "    if (a) { ret = 1; }\n"
+                        "    else { s=foo(1,{2,3},4); ret = 2; }\n"
+                        "    return ret;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        // conditional initialization
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    if (y == 1) { x = 1; }\n"
+                        "    else { if (y == 2) { x = 1; } }\n"
+                        "    return x;\n"
+                        "}");
+        TODO_ASSERT_EQUALS("[test.cpp:5]: (error) Uninitialized variable: x\n", "", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    if (y == 1) { x = 1; }\n"
+                        "    else { if (y == 2) { x = 1; } }\n"
+                        "    if (y == 3) { }\n" // <- ignore condition
+                        "    return x;\n"
+                        "}");
+        TODO_ASSERT_EQUALS("[test.cpp:6]: (error) Uninitialized variable: x\n", "", errout.str());
+
+        // initialization in condition
+        valueFlowUninit("void f() {\n"
+                        "    int a;\n"
+                        "    if (init(&a)) { }\n"
+                        "    a++;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        // return, break, continue, goto
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    if (y == 1) { return; }\n"
+                        "    else { x = 1; }\n"
+                        "    return x;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    if (y == 1) { return; }\n"
+                        "    return x;\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:4]: (error) Uninitialized variable: x\n", errout.str());
+
+        valueFlowUninit("int f(int x) {\n"
+                        "    int ret;\n"
+                        "    if (!x) {\n"
+                        "        ret = -123;\n"
+                        "        goto out1;\n"
+                        "    }\n"
+                        "    return 0;\n"
+                        "out1:\n"
+                        "out2:\n"
+                        "    return ret;\n"
+                        "}",
+                        "test.c");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int i;\n"
+                        "    if (x) {\n"
+                        "        i = 1;\n"
+                        "    } else {\n"
+                        "        goto out;\n"
+                        "    }\n"
+                        "    i++;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("int f() {\n"
+                        "    int i,x;\n"
+                        "    for (i=0;i<9;++i)\n"
+                        "        if (foo) break;\n"
+                        "    return x;\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:4] -> [test.cpp:5]: (error) Uninitialized variable: x\n", errout.str());
+
+        valueFlowUninit("int f() {\n"
+                        "    int x;\n"
+                        "    while (foo)\n"
+                        "        if (bar) break;\n"
+                        "    return x;\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:4] -> [test.cpp:5]: (error) Uninitialized variable: x\n", errout.str());
+
+        // try/catch : don't warn about exception variable
+        valueFlowUninit("void f() {\n"
+                        "    try {\n"
+                        "    } catch (CException* e) {\n"
+                        "        trace();\n"
+                        "        e->Delete();\n"
+                        "    }\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n" // #5347
+                        "    try {\n"
+                        "    } catch (const char* e) {\n"
+                        "        A a = e;\n"
+                        "    }\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        // exit
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    if (y == 1) { exit(0); }\n"
+                        "    else { x = 1; }\n"
+                        "    return x;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        // strange code.. don't crash (#3415)
+        valueFlowUninit("void foo() {\n"
+                        "    int i;\n"
+                        "    ({ if (0); });\n"
+                        "    for_each(i) { }\n"
+                        "}",
+                        "test.c");
+
+        // if, if
+        valueFlowUninit("void f(int a) {\n"
+                        "    int i;\n"
+                        "    if (a) i = 0;\n"
+                        "    if (a) i++;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int a,b=0;\n"
+                        "    if (x) {\n"
+                        "        if (y) {\n"
+                        "            a = 0;\n"
+                        "            b = 1;\n"
+                        "        }\n"
+                        "    }\n"
+                        "    if (b) a++;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int a=0, b;\n"
+                        "    if (x) { }\n"
+                        "    else { if (y==2) { a=1; b=2; } }\n"
+                        "    if (a) { ++b; }\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("static void f(int x, int y) {\n"
+                        "    int a;\n"
+                        "    if (x == 0) { a = y; }\n"
+                        "    if (x == 0 && (a == 1)) { }\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("static void f() {\n"
+                        "    int a=0, b;\n"
+                        "    if (something) { a = dostuff(&b); }\n"
+                        "    if (!a || b) { }\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("static void f(int x, int y) {\n"
+                        "    int a;\n"
+                        "    if (x == 0 && (a == 1)) { }\n"
+                        "}",
+                        "test.cpp");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: a\n", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int a;\n"
+                        "    if (x) { a = 0; }\n"
+                        "    if (x) { if (y) { a++; } }\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int a;\n"
+                        "    if (x) { a = 0; }\n"
+                        "    if (x) { if (y) { } else { a++; } }\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("struct AB { int a; int b; };\n"
+                        "void f(void) {\n"
+                        "    struct AB ab;\n"
+                        "    if (x) ab = getAB();\n"
+                        "    else ab.a = 0;\n"
+                        "    if (ab.a == 1) b = ab.b;\n"
+                        "}",
+                        "test.c");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("int f(void) {\n"
+                        "    int a;\n"
+                        "    int i;\n"
+                        "    if (x) { noreturn(); }\n"
+                        "    else { i = 0; }\n"
+                        "    if (i==1) { a = 0; }\n"
+                        "    else { a = 1; }\n"
+                        "    return a;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("int f(int a) {\n" // #4560
+                        "    int x = 0, y;\n"
+                        "    if (a) x = 1;\n"
+                        "    else return 0;\n"
+                        "    if (x) y = 123;\n" // <- y is always initialized
+                        "    else {}\n"
+                        "    return y;\n"
+                        "}");
+        TODO_ASSERT_EQUALS("", "[test.cpp:5] -> [test.cpp:7]: (warning) Uninitialized variable: y\n", errout.str());
+
+        valueFlowUninit("int f(int a) {\n" // #6583
+                        "    int x;\n"
+                        "    if (a < 2) exit(1);\n"
+                        "    else if (a == 2) x = 0;\n"
+                        "    else exit(2);\n"
+                        "    return x;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("int f(int a) {\n" // #4560
+                        "    int x = 1, y;\n"
+                        "    if (a) x = 0;\n"
+                        "    else return 0;\n"
+                        "    if (x) {}\n"
+                        "    else y = 123;\n" // <- y is always initialized
+                        "    return y;\n"
+                        "}");
+        TODO_ASSERT_EQUALS("", "[test.cpp:5] -> [test.cpp:7]: (warning) Uninitialized variable: y\n", errout.str());
+
+        valueFlowUninit("void f(int x) {\n" // #3948
+                        "  int value;\n"
+                        "  if (x !=-1)\n"
+                        "    value = getvalue();\n"
+                        "  if (x == -1 || value > 300) {}\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("enum t_err { ERR_NONE, ERR_BAD_ARGS };\n" // #9649
+                        "struct box_t { int value; };\n"
+                        "int init_box(box_t *p, int v);\n"
+                        "\n"
+                        "void foo(int ret) {\n"
+                        "    box_t box2;\n"
+                        "    if (ret == ERR_NONE)\n"
+                        "        ret = init_box(&box2, 20);\n"
+                        "    if (ret == ERR_NONE)\n"
+                        "        z = x + box2.value;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f(int x) {\n"
+                        "  int value;\n"
+                        "  if (x == 32)\n"
+                        "    value = getvalue();\n"
+                        "  if (x == 1)\n"
+                        "    v = value;\n"
+                        "}");
+        TODO_ASSERT_EQUALS("[test.cpp:6]: (error) Uninitialized variable: value\n", "", errout.str());
+
+        valueFlowUninit("void f(int x) {\n"
+                        "  int value;\n"
+                        "  if (x == 32)\n"
+                        "    value = getvalue();\n"
+                        "  if (x == 32) {}\n"
+                        "  else v = value;\n"
+                        "}");
+        ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:6]: (warning) Uninitialized variable: value\n", errout.str());
+
+        valueFlowUninit("static int x;" // #4773
+                        "int f() {\n"
+                        "    int y;\n"
+                        "    if (x) g();\n"
+                        "    if (x) y = 123;\n"
+                        "    else y = 456;\n"
+                        "    return y;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("static int x;" // #4773
+                        "int f() {\n"
+                        "    int y;\n"
+                        "    if (!x) g();\n"
+                        "    if (x) y = 123;\n"
+                        "    else y = 456;\n"
+                        "    return y;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f(int a) {\n"
+                        "  int x;\n"
+                        "  if (a) x=123;\n"
+                        "  if (!a) {\n"
+                        "    if (!a) {}\n"
+                        "    else if (x) {}\n"
+                        "  }\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        // asm
+        valueFlowUninit("void f() {\n"
+                        "    int x;\n"
+                        "    asm();\n"
+                        "    x++;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        // sizeof / typeof / offsetof / etc
+        valueFlowUninit("void f() {\n"
+                        "    int i;\n"
+                        "    sizeof(i+1);\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int i;\n"
+                        "    if (100 == sizeof(i+1));\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    struct ABC *abc;\n"
+                        "    int i = ARRAY_SIZE(abc.a);"
+                        "}");
+        // FP ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    int *abc;\n"
+                        "    typeof(*abc);\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    struct ABC *abc;\n"
+                        "    return do_something(typeof(*abc));\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n"
+                        "    A *a;\n"
+                        "    a = malloc(sizeof(*a));\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        // &
+        valueFlowUninit("void f() {\n" // #4426 - address of uninitialized variable
+                        "    int a,b;\n"
+                        "    if (&a == &b);\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit("void f() {\n" // #4439 - cast address of uninitialized variable
+                        "    int a;\n"
+                        "    x((LPARAM)(RECT*)&a);\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
+        valueFlowUninit(
+            "int main() {\n"
+            "    int done;\n"
+            "    dostuff(1, (AuPointer) &done);\n" // <- It is not conclusive if the "&" is a binary or unary operator. Bailout.
+            "}");
+        TODO_ASSERT_EQUALS("", "[test.cpp:3]: (error) Uninitialized variable: done\n", errout.str());
+
+        valueFlowUninit("void f() {\n" // #4778 - cast address of uninitialized variable
+                        "    long a;\n"
+                        "    &a;\n"
+                        "}");
+        TODO_ASSERT_EQUALS("", "[test.cpp:3]: (error) Uninitialized variable: &a\n", errout.str());
+
+        valueFlowUninit("void f() {\n" // #4717 - ({})
+                        "    int a = ({ long b = (long)(123); 2 + b; });\n"
+                        "}",
+                        "test.c");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void uninitStructMember() { // struct members
         checkUninitVar("struct AB { int a; int b; };\n"
                        "void f(void) {\n"

test/testvalueflow.cpp

@@ -4633,6 +4633,85 @@ private:
                "    return x;\n"
                "}\n";
         ASSERT_EQUALS(true, testValueOfX(code, 6U, 0));
+
+        code = "int* g(int& i, bool b) {\n"
+               "    if(b)\n"
+               "        return nullptr;\n"
+               "    return &i;\n"
+               "}   \n"
+               "int f(int i) {\n"
+               "    int* x = g(i, true);\n"
+               "    return x;\n"
+               "}\n";
+        ASSERT_EQUALS(true, testValueOfX(code, 8U, 0));
+
+        code = "int* g(int& i, bool b) {\n"
+               "    if(b)\n"
+               "        return nullptr;\n"
+               "    return &i;\n"
+               "}   \n"
+               "int f(int i) {\n"
+               "    int* x = g(i, false);\n"
+               "    return x;\n"
+               "}\n";
+        ASSERT_EQUALS(true, testValueOfXImpossible(code, 8U, 0));
+
+        code = "int* g(int& i, bool b) {\n"
+               "    if(b)\n"
+               "        return nullptr;\n"
+               "    return &i;\n"
+               "}   \n"
+               "int f(int i) {\n"
+               "    int* x = g(i, i == 3);\n"
+               "    return x;\n"
+               "}\n";
+        ASSERT_EQUALS(false, testValueOfX(code, 8U, 0));
+
+        code = "struct A {\n"
+               "    unsigned i;\n"
+               "    bool f(unsigned x) const {\n"
+               "        return ((i & x) != 0);\n"
+               "    }\n"
+               "};\n"
+               "int g(A& a) {\n"
+               "    int x = a.f(2);\n"
+               "    return x;\n"
+               "}\n";
+        ASSERT_EQUALS(false, testValueOfX(code, 9U, 0));
+        ASSERT_EQUALS(false, testValueOfX(code, 9U, 1));
+        ASSERT_EQUALS(false, testValueOfXImpossible(code, 9U, 0));
+        ASSERT_EQUALS(false, testValueOfXImpossible(code, 9U, 1));
+
+        code = "struct A {\n"
+               "    enum {\n"
+               "        b = 0,\n"
+               "        c = 1,\n"
+               "        d = 2\n"
+               "    };\n"
+               "    bool isb() const {\n"
+               "        return e == b;\n"
+               "    }\n"
+               "    unsigned int e;\n"
+               "};\n"
+               "int f(A g) {\n"
+               "  int x = !g.isb();\n"
+               "  return x;\n"
+               "}\n";
+        ASSERT_EQUALS(false, testValueOfX(code, 14U, 0));
+        ASSERT_EQUALS(false, testValueOfX(code, 14U, 1));
+
+        code = "bool h(char q);\n"
+               "bool g(char q) {\n"
+               "    if (!h(q))\n"
+               "        return false;\n"
+               "    return true;\n"
+               "}\n"
+               "int f() {\n"
+               "    int x = g(0);\n"
+               "    return x;\n"
+               "}\n";
+        ASSERT_EQUALS(false, testValueOfX(code, 9U, 0));
+        ASSERT_EQUALS(false, testValueOfX(code, 9U, 1));
     }
 
     void valueFlowFunctionDefaultParameter() {

tools/run_more_tests.sh

@@ -20,86 +20,85 @@ cd test1
 
 $CPPCHECK -q --template=cppcheck1 . 2> 1.txt
 
-
-# (!x) => (x==0)
+echo "(!x) => (x==0)"
 $SED_CMD -ri 's/([(&][ ]*)\!([a-z]+)([ ]*[&)])/\1\2==0\3/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (x==0) => (0==x)
+echo "(x==0) => (0==x)"
 $SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*==[ ]*0([ ]*[&)])/\10==\2\3/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (0==x) => (!x)
+echo "(0==x) => (!x)"
 $SED_CMD -ri 's/([(&][ ]*)0[ ]*==[ ]*([a-z]+)([ ]*[&)])/\1!\2\3/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 
 
 
-# if (x) => (x!=0)
+echo "if (x) => (x!=0)"
 $SED_CMD -ri 's/(if[ ]*\([ ]*[a-z]+)([ ]*[&)])/\1!=0\2/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# while (x) => (x!=0)
+echo "while (x) => (x!=0)"
 $SED_CMD -ri 's/(while[ ]*\([ ]*[a-z]+)([ ]*[&)])/\1!=0\2/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (x!=0) => (0!=x)
+echo "(x!=0) => (0!=x)"
 $SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*!=[ ]*0([ ]*[&)])/\10!=\2\3/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (0!=x) => (x)
+echo "(0!=x) => (x)"
 $SED_CMD -ri 's/([(&][ ]*)0[ ]*!=[ ]*([a-z]+[ ]*[&)])/\1\2/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 
-# (x < 0) => (0 > x)
+echo "(x < 0) => (0 > x)"
 $SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*<[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (x <= 0) => (0 >= x)
+echo "(x <= 0) => (0 >= x)"
 $SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*<=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (x > 0) => (0 < x)
+echo "(x > 0) => (0 < x)"
 $SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*<=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (x >= 0) => (0 <= x)
+echo "(x >= 0) => (0 <= x)"
 $SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*<=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (x == 123) => (123 == x)
+echo "(x == 123) => (123 == x)"
 $SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*==[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3==\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (x != 123) => (123 != x)
+echo "(x != 123) => (123 != x)"
 $SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*\!=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3!=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 
 
-# (0 < x) => (x > 0)
+echo "(0 < x) => (x > 0)"
 $SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<[ ]*([a-z]+)([ ]*[&)])/\1\3>\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (0 <= x) => (x >= 0)
+echo "(0 <= x) => (x >= 0)"
 $SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<=[ ]*([a-z]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (0 > x) => (x < 0)
+echo "(0 > x) => (x < 0)"
 $SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<=[ ]*([a-z]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (0 >= x) => (x <= 0)
+echo "(0 >= x) => (x <= 0)"
 $SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<=[ ]*([a-z]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (123 == x) => (x == 123)
+echo "(123 == x) => (x == 123)"
 $SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*==[ ]*([a-z]+)([ ]*[&)])/\1\3==\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
-# (123 != x) => (x <= 123)
+echo "(123 != x) => (x <= 123)"
 $SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*\!=[ ]*([a-z]+)([ ]*[&)])/\1\3!=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt