Fix 10575: Improve check; lifetime, struct member points to local data (#3541)

Author: pfultz2

lib/checkautovariables.cpp

@@ -496,13 +496,22 @@ static bool isDanglingSubFunction(const Token* tokvalue, const Token* tok)
     return exprDependsOnThis(parent);
 }
 
+static const Variable* getParentVar(const Token* tok)
+{
+    if (!tok)
+        return nullptr;
+    if (Token::simpleMatch(tok, "."))
+        return getParentVar(tok->astOperand1());
+    return tok->variable();
+}
+
 static bool isAssignedToNonLocal(const Token* tok)
 {
     if (!Token::simpleMatch(tok->astParent(), "="))
         return false;
-    if (!Token::Match(tok->astParent()->astOperand1(), "%var%"))
+    if (!astIsRHS(tok))
         return false;
-    const Variable* var = tok->astParent()->astOperand1()->variable();
+    const Variable* var = getParentVar(tok->astParent()->astOperand1());
     if (!var)
         return false;
     return !var->isLocal() || var->isStatic();
@@ -597,8 +606,8 @@ void CheckAutoVariables::checkVarLifetimeScope(const Token * start, const Token
                     const Variable * var = nullptr;
                     const Token * tok2 = tok;
                     if (Token::simpleMatch(tok->astParent(), "=")) {
-                        if (tok->astParent()->astOperand2() == tok) {
-                            var = getLHSVariable(tok->astParent());
+                        if (astIsRHS(tok)) {
+                            var = getParentVar(tok->astParent()->astOperand1());
                             tok2 = tok->astParent()->astOperand1();
                         }
                     } else if (tok->variable() && tok->variable()->declarationId() == tok->varId()) {

test/testautovariables.cpp

@@ -2833,6 +2833,25 @@ class TestAutoVariables : public TestFixture {
               "    auto getMore() -> int & { return get(); }\n"
               "};\n");
         ASSERT_EQUALS("", errout.str());
+
+        // #10575
+        check("struct Data {\n"
+              "    int x=0;\n"
+              "    int y=0;\n"
+              "};\n"
+              "struct MoreData {\n"
+              "    Data *data1;\n"
+              "};\n"
+              "struct Fred {\n"
+              "    Fred() {\n"
+              "        Data data;\n"
+              "        mMoreData.data1 = &data;\n"
+              "    }\n"
+              "    MoreData mMoreData;\n"
+              "};\n");
+        ASSERT_EQUALS(
+            "[test.cpp:11] -> [test.cpp:10] -> [test.cpp:11]: (error) Non-local variable 'mMoreData.data1' will use pointer to local variable 'data'.\n",
+            errout.str());
     }
 
     void danglingLifetimeFunction() {