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

lib/checkuninitvar.cpp

@@ -1103,13 +1103,29 @@ void CheckUninitVar::checkScope(const Scope* scope)
                 if (scope2->className == structname && scope2->numConstructors == 0U) {
                     for (std::list<Variable>::const_iterator it = scope2->varlist.begin(); it != scope2->varlist.end(); ++it) {
                         const Variable &var = *it;
-                        if (!var.isArray())
+                        if (!var.isArray()) {
+                            // is the variable declared in a inner union?
+                            bool innerunion = false;
+                            for (std::list<Scope>::const_iterator it2 = symbolDatabase->scopeList.begin(); it2 != symbolDatabase->scopeList.end(); it2++) {
+                                const Scope &innerScope = *it2;
+                                if (innerScope.type == Scope::eUnion && innerScope.nestedIn == scope2) {
+                                    if (var.typeStartToken()->linenr() >= innerScope.classStart->linenr() &&
+                                        var.typeStartToken()->linenr() <= innerScope.classEnd->linenr()) {
+                                        innerunion = true;
+                                        break;
+                                    }
+
+                                }
+                            }
+
+                            if (!innerunion)
                                 checkScopeForVariable(scope, tok, *i, NULL, NULL, var.name());
                         }
                     }
                 }
             }
         }
+    }
 }
 
 static void conditionAlwaysTrueOrFalse(const Token *tok, const std::map<unsigned int, int> &variableValue, bool *alwaysTrue, bool *alwaysFalse)

test/testuninitvar.cpp

@@ -2788,6 +2788,20 @@ private:
                         "}\n", "test.c");
         ASSERT_EQUALS("", errout.str());
 
+        checkUninitVar2("struct PIXEL {\n"
+                        "    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"
+                        "}\n");
+        ASSERT_EQUALS("", errout.str());
+
         // return
         checkUninitVar2("struct AB { int a; int b; };\n"
                         "void f(void) {\n"