Fix 13046: false negative: knownConditionTrueFalse with this (danmar#7432)

Author: pfultz2

lib/valueflow.cpp

@@ -5858,29 +5858,41 @@ static const ValueFlow::Value* getKnownValueFromToken(const Token* tok)
     return std::addressof(*it);
 }
 
-static const ValueFlow::Value* getKnownValueFromTokens(const std::vector<const Token*>& toks)
+static std::vector<ValueFlow::Value> getCommonValuesFromTokens(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 {};
+    std::vector<ValueFlow::Value> result;
+    std::copy_if(toks.front()->values().begin(),
+                 toks.front()->values().end(),
+                 std::back_inserter(result),
+                 [&](const ValueFlow::Value& v) {
+        if (!v.isKnown() && !v.isImpossible())
+            return false;
+        return (v.isIntValue() || v.isContainerSizeValue() || v.isFloatValue());
+    });
+    std::for_each(toks.begin() + 1, toks.end(), [&](const Token* tok) {
+        auto it = std::remove_if(result.begin(), result.end(), [&](const ValueFlow::Value& v) {
+            return std::none_of(tok->values().begin(), tok->values().end(), [&](const ValueFlow::Value& v2) {
+                return v.equalValue(v2) && v.valueKind == v2.valueKind;
+            });
         });
-    }))
-        return nullptr;
+        result.erase(it, result.end());
+    });
     return result;
 }
 
-static void setFunctionReturnValue(const Function* f, Token* tok, ValueFlow::Value v, const Settings& settings)
+static void setFunctionReturnValue(const Function* f,
+                                   Token* tok,
+                                   ValueFlow::Value v,
+                                   const Settings& settings,
+                                   bool known = true)
 {
     if (f->hasVirtualSpecifier()) {
         if (v.isImpossible())
             return;
         v.setPossible();
-    } else if (!v.isImpossible()) {
+    } else if (!v.isImpossible() && known) {
         v.setKnown();
     }
     v.errorPath.emplace_back(tok, "Calling function '" + f->name() + "' returns " + v.toString());
@@ -5911,11 +5923,17 @@ static void valueFlowFunctionReturn(TokenList& tokenlist, ErrorLogger& errorLogg
         if (returns.empty())
             continue;
 
-        if (const ValueFlow::Value* v = getKnownValueFromTokens(returns)) {
-            setFunctionReturnValue(function, tok, *v, settings);
-            continue;
+        bool hasKnownValue = false;
+
+        for (const ValueFlow::Value& v : getCommonValuesFromTokens(returns)) {
+            setFunctionReturnValue(function, tok, v, settings, false);
+            if (v.isKnown())
+                hasKnownValue = true;
         }
 
+        if (hasKnownValue)
+            continue;
+
         // Arguments..
         std::vector<const Token*> arguments = getArguments(tok);
 

test/testcondition.cpp

@@ -4760,6 +4760,21 @@ class TestCondition : public TestFixture {
               "}");
         ASSERT_EQUALS("", errout_str());
 
+        check("struct S {\n"
+              "    const S* get2() const {\n"
+              "        if (mS)\n"
+              "            return mS;\n"
+              "        return this;\n"
+              "    }\n"
+              "    S* mS = nullptr;\n"
+              "};\n"
+              "void f2() {\n"
+              "    const S s;\n"
+              "    const S* sp2 = s.get2();\n"
+              "    if (sp2) {}\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:12]: (style) Condition 'sp2' is always true\n", errout_str());
+
         check("struct S {\n"
               "    void f(int i);\n"
               "    bool g() const { return !m.empty(); }\n"