Fix #12607 FP returnReference with std::map (regression) (#6278)

Author: chrchr-github

lib/valueflow.cpp

@@ -3665,10 +3665,14 @@ static std::vector<ValueFlow::LifetimeToken> getLifetimeTokens(const Token* tok,
 
         const Token *vartok = tok;
         while (vartok) {
-            if (vartok->str() == "[" || vartok->originalName() == "->" || vartok->isUnaryOp("*"))
-                vartok = vartok->astOperand1();
-            else if (vartok->str() == ".")
+            if (vartok->str() == "[" || vartok->isUnaryOp("*"))
                 vartok = vartok->astOperand1();
+            else if (vartok->str() == ".") {
+                if (vartok->originalName().empty() || !Token::simpleMatch(vartok->astOperand1(), "."))
+                    vartok = vartok->astOperand1();
+                else
+                    break;
+            }
             else if (vartok->str() == "::")
                 vartok = vartok->astOperand2();
             else

test/testautovariables.cpp

@@ -115,6 +115,7 @@ class TestAutoVariables : public TestFixture {
         TEST_CASE(returnReference24); // #10098
         TEST_CASE(returnReference25); // #10983
         TEST_CASE(returnReference26);
+        TEST_CASE(returnReference27);
         TEST_CASE(returnReferenceFunction);
         TEST_CASE(returnReferenceContainer);
         TEST_CASE(returnReferenceLiteral);
@@ -1656,6 +1657,18 @@ class TestAutoVariables : public TestFixture {
         ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:4]: (error) Reference to local variable returned.\n", errout_str());
     }
 
+    void returnReference27()
+    {
+        check("struct S {\n" // #12607
+              "    const std::string & f(const std::string& a, const std::string& b) {\n"
+              "        auto status = m.emplace(a, b);\n"
+              "        return status.first->second;\n"
+              "    }\n"
+              "    std::map<std::string, std::string> m;\n"
+              "};\n");
+        ASSERT_EQUALS("", errout_str());
+    }
+
     void returnReferenceFunction() {
         check("int& f(int& a) {\n"
               "    return a;\n"