Fix #12128 FP uninitDerivedMemberVar with brace init (#5606)

Author: chrchr-github

lib/checkclass.cpp

@@ -764,7 +764,14 @@ void CheckClass::initializeVarList(const Function &func, std::list<const Functio
         if (initList) {
             if (level == 0 && Token::Match(ftok, "%name% {|(") && Token::Match(ftok->linkAt(1), "}|) ,|{")) {
                 if (ftok->str() != func.name()) {
-                    initVar(usage, ftok->varId());
+                    if (ftok->varId())
+                        initVar(usage, ftok->varId());
+                    else { // base class constructor
+                        for (Usage& u : usage) {
+                            if (u.var->scope() != scope) // assume that all variables are initialized in base class
+                                u.init = true;
+                        }
+                    }
                 } else { // c++11 delegate constructor
                     const Function *member = ftok->function();
                     // member function not found => assume it initializes all members

test/testconstructors.cpp

@@ -1467,6 +1467,22 @@ class TestConstructors : public TestFixture {
               "}\n");
         ASSERT_EQUALS("", errout.str());
 
+        check("template <class T>\n" // #12128
+              "struct B {\n"
+              "    T x;\n"
+              "};\n"
+              "struct D : B<double> {\n"
+              "    D(double x) : B{ x } {}\n"
+              "};\n");
+        ASSERT_EQUALS("", errout.str());
+
+        check("struct B {\n"
+              "    int x;\n"
+              "};\n"
+              "struct D : B {\n"
+              "    D(int i) : B{ i } {}\n"
+              "};\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void initvar_derived_pod_struct_with_union() {