Fix #12139 FP redundantCopyLocalConst for small type (#5617)

Author: chrchr-github

lib/checkother.cpp

@@ -2886,7 +2886,8 @@ void CheckOther::checkRedundantCopy()
             const Scope* fScope = func->functionScope;
             if (fScope && fScope->bodyEnd && Token::Match(fScope->bodyEnd->tokAt(-3), "return %var% ;")) {
                 const Token* varTok = fScope->bodyEnd->tokAt(-2);
-                if (varTok->variable() && !varTok->variable()->isGlobal())
+                if (varTok->variable() && !varTok->variable()->isGlobal() &&
+                    (!varTok->variable()->type() || estimateSize(varTok->variable()->type(), mSettings, symbolDatabase) > 2 * mSettings->platform.sizeof_pointer))
                     redundantCopyError(startTok, startTok->str());
             }
         }

test/testother.cpp

@@ -8427,7 +8427,7 @@ class TestOther : public TestFixture {
               "}");
         ASSERT_EQUALS("[test.cpp:3]: (performance, inconclusive) Use const reference for 'a' to avoid unnecessary data copying.\n", errout.str());
 
-        check("class A{public:A(){}};\n"
+        check("class A { public: A() {} char x[100]; };\n"
               "const A& getA(){static A a;return a;}\n"
               "int main()\n"
               "{\n"
@@ -8453,7 +8453,7 @@ class TestOther : public TestFixture {
               "}");
         ASSERT_EQUALS("[test.cpp:1] -> [test.cpp:4]: (style) Local variable \'getA\' shadows outer function\n", errout.str());
 
-        check("class A{public:A(){}};\n"
+        check("class A { public: A() {} char x[100]; };\n"
               "const A& getA(){static A a;return a;}\n"
               "int main()\n"
               "{\n"
@@ -8604,6 +8604,19 @@ class TestOther : public TestFixture {
               "    std::string s = getC().get();\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        check("struct S {\n" // #12139
+              "    int x, y;\n"
+              "};\n"
+              "struct T {\n"
+              "    S s;\n"
+              "    const S& get() const { return s; }\n"
+              "};\n"
+              "void f(const T& t) {\n"
+              "    const S a = t.get();\n"
+              "    if (a.x > a.y) {}\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void checkNegativeShift() {