Fixed #4907 (False positive "uninitStructMember" on structs with unions)

lib/checkuninitvar.cpp

@@ -1101,11 +1101,22 @@ void CheckUninitVar::checkScope(const Scope* scope)
             for (std::size_t j = 0U; j < symbolDatabase->classAndStructScopes.size(); ++j) {
                 const Scope *scope2 = symbolDatabase->classAndStructScopes[j];
                 if (scope2->className == structname && scope2->numConstructors == 0U) {
+                    bool hasUnion = false;
+                    for (std::list<Scope*>::const_iterator childscope = scope2->nestedList.begin();
+                         childscope != scope2->nestedList.end();
+                         ++childscope) {
+                        if ((*childscope)->type == Scope::eUnion)
+                            hasUnion = true;
+                    }
+                    if (hasUnion)
+                        break;
+
                     for (std::list<Variable>::const_iterator it = scope2->varlist.begin(); it != scope2->varlist.end(); ++it) {
                         const Variable &var = *it;
                         if (!var.isArray())
                             checkScopeForVariable(scope, tok, *i, NULL, NULL, var.name());
                     }
+                    break;
                 }
             }
         }

test/testuninitvar.cpp

@@ -2788,6 +2788,20 @@ private:
                         "}\n", "test.c");
         ASSERT_EQUALS("", errout.str());
 
+        checkUninitVar2("struct PIXEL {\n" // union in struct #4970
+                        "    union  {\n"
+                        "        struct { unsigned char red,green,blue,alpha; };\n"
+                        "        unsigned int color;\n"
+                        "    };\n"
+                        "};\n"
+                        "\n"
+                        "unsigned char f() {\n"
+                        "    struct PIXEL p1;\n"
+                        "    p1.color = 255;\n"
+                        "    return p1.red;\n"
+                        "}");
+        ASSERT_EQUALS("", errout.str());
+
         // return
         checkUninitVar2("struct AB { int a; int b; };\n"
                         "void f(void) {\n"