Fix #12773 FP accessMoved using try_emplace() together with std::move() (#8421)

Author: chrchr-github

lib/valueflow.cpp

@@ -3223,6 +3223,14 @@ static Token* findEndOfFunctionCallForParameter(Token* parameterToken)
     return nextAfterAstRightmostLeaf(parent);
 }
 
+static bool isTryEmplace(const Token* tok)
+{
+    if (tok->str() != "(" || !Token::simpleMatch(tok->astOperand1(), ".") || !tok->astOperand1()->astOperand1() || !Token::simpleMatch(tok->astOperand1()->astOperand2(), "try_emplace"))
+        return false;
+    const ValueType* vt = tok->astOperand1()->astOperand1()->valueType();
+    return vt && vt->container && vt->container->stdAssociativeLike;
+}
+
 static void valueFlowAfterMove(const TokenList& tokenlist, const SymbolDatabase& symboldatabase, ErrorLogger& errorLogger, const Settings& settings)
 {
     if (!tokenlist.isCPP() || settings.standards.cpp < Standards::CPP11)
@@ -3265,9 +3273,17 @@ static void valueFlowAfterMove(const TokenList& tokenlist, const SymbolDatabase&
             const nonneg int varId = varTok->varId();
             // x is not MOVED after assignment if code is:  x = ... std::move(x) .. ;
             const Token *parent = tok->astParent();
+            bool bail = false;
             while (parent && parent->str() != "=" && parent->str() != "return" &&
-                   !(parent->str() == "(" && isOpenParenthesisMemberFunctionCallOfVarId(parent, varId)))
+                   !(parent->str() == "(" && isOpenParenthesisMemberFunctionCallOfVarId(parent, varId))) {
+                if (isTryEmplace(parent)) {
+                    bail = true;
+                    break;
+                }
                 parent = parent->astParent();
+            }
+            if (bail)
+                continue;
             if (parent &&
                 (parent->str() == "return" || // MOVED in return statement
                  parent->str() == "(")) // MOVED in self assignment, isOpenParenthesisMemberFunctionCallOfVarId == true

test/testother.cpp

@@ -305,6 +305,7 @@ class TestOther : public TestFixture {
         TEST_CASE(moveTernary);
         TEST_CASE(movePointerAlias);
         TEST_CASE(moveOutparam);
+        TEST_CASE(moveTryEmplace);
 
         TEST_CASE(funcArgNamesDifferent);
         TEST_CASE(funcArgOrderDifferent);
@@ -12752,6 +12753,17 @@ class TestOther : public TestFixture {
         ASSERT_EQUALS("", errout_str());
     }
 
+    void moveTryEmplace()
+    {
+        check("void f(std::map<std::string, std::string>& m, std::string& s) {\n" // #12773
+              "    bool b = m.try_emplace(\"a\", std::move(s)).second;\n"
+              "    if (!b) {\n"
+              "        std::cout << s;\n"
+              "    }\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
+    }
+
     void funcArgNamesDifferent() {
         check("void func1(int a, int b, int c);\n"
               "void func1(int a, int b, int c) { }\n"