Fix #14013 FP invalidContainerReference with emplace_back() (danmar#7672)

Author: chrchr-github

lib/checkstl.cpp

@@ -1202,6 +1202,11 @@ void CheckStl::invalidContainer()
                         if (info.tok->variable()->isReference() && !isVariableDecl(info.tok) &&
                             reaches(info.tok->variable()->nameToken(), tok, nullptr)) {
 
+                            if ((assignExpr && Token::Match(assignExpr->astOperand1(), "& %varid%", info.tok->varId())) || // TODO: fix AST
+                                Token::Match(assignExpr, "& %varid% {|(", info.tok->varId())) {
+                                return false;
+                            }
+
                             ErrorPath ep;
                             bool addressOf = false;
                             const Variable* var = ValueFlow::getLifetimeVariable(info.tok, ep, *mSettings, &addressOf);

test/teststl.cpp

@@ -6533,6 +6533,28 @@ class TestStl : public TestFixture {
         ASSERT_EQUALS(
             "[test.cpp:4:7] -> [test.cpp:7:5] -> [test.cpp:8:7]: (error) Calling 'add' while iterating the container is invalid. [invalidContainerLoop]\n",
             errout_str());
+
+        check("struct S { int i; };\n" // #14013
+              "void f() {\n"
+              "    std::vector<std::unique_ptr<S>> v;\n"
+              "    for (int i = 0; i < 5; ++i) {\n"
+              "        std::unique_ptr<S>& r = v.emplace_back(std::make_unique<S>());\n"
+              "        r->i = 1;\n"
+              "    }\n"
+              "}\n",
+              dinit(CheckOptions, $.inconclusive = true));
+        ASSERT_EQUALS("", errout_str());
+
+        check("struct S { int i; };\n"
+              "void f() {\n"
+              "    std::vector<std::unique_ptr<S>> v;\n"
+              "    for (int i = 0; i < 5; ++i) {\n"
+              "        std::unique_ptr<S>& r{ v.emplace_back(std::make_unique<S>()) };\n"
+              "        r->i = 1;\n"
+              "    }\n"
+              "}\n",
+              dinit(CheckOptions, $.inconclusive = true));
+        ASSERT_EQUALS("", errout_str());
     }
 
     void findInsert() {