Fix 13478: FP knownConditionTrueFalse after member is modified (#7431)

Author: pfultz2

lib/vf_analyzers.cpp

@@ -85,7 +85,7 @@ struct ValueFlowAnalyzer : Analyzer {
     virtual bool dependsOnThis() const {
         return false;
     }
-    virtual bool isVariable() const {
+    virtual bool isClassVariable() const {
         return false;
     }
 
@@ -643,7 +643,7 @@ struct ValueFlowAnalyzer : Analyzer {
             if (a != Action::None)
                 return a;
         }
-        if (dependsOnThis() && exprDependsOnThis(tok, !isVariable()))
+        if (dependsOnThis() && exprDependsOnThis(tok, !isClassVariable()))
             return isThisModified(tok);
 
         // bailout: global non-const variables
@@ -1315,7 +1315,12 @@ struct ExpressionAnalyzer : SingleValueFlowAnalyzer {
         return !local;
     }
 
-    bool isVariable() const override {
+    bool isClassVariable() const override
+    {
+        if (expr->variable()) {
+            const Variable* var = expr->variable();
+            return !var->isLocal() && !var->isArgument() && !var->isStatic() && !var->isGlobal();
+        }
         return expr->varId() > 0;
     }
 

test/testcondition.cpp

@@ -4759,6 +4759,21 @@ class TestCondition : public TestFixture {
               "    return b ? 1 : 0;\n"
               "}");
         ASSERT_EQUALS("", errout_str());
+
+        check("struct S {\n"
+              "    void f(int i);\n"
+              "    bool g() const { return !m.empty(); }\n"
+              "    std::set<int> m;\n"
+              "};\n"
+              "void S::f(int i) {\n"
+              "    bool b = g();\n"
+              "    auto it = m.find(i);\n"
+              "    if (it != m.end()) {\n"
+              "        m.erase(it);\n"
+              "        if (g() != b) {}\n"
+              "    }\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
     }
 
     void alwaysTrueSymbolic()