+/**
+ * Check if a given type is incomplete
+ */
+bool is_type_incomplete(const type_t *type)
+{
+ assert(!is_typeref(type));
+
+ switch(type->kind) {
+ case TYPE_COMPOUND_STRUCT:
+ case TYPE_COMPOUND_UNION: {
+ const compound_type_t *compound_type = &type->compound;
+ declaration_t *declaration = compound_type->declaration;
+ return !declaration->init.is_defined;
+ }
+ case TYPE_ENUM: {
+ const enum_type_t *enum_type = &type->enumt;
+ declaration_t *declaration = enum_type->declaration;
+ return !declaration->init.is_defined;
+ }
+ case TYPE_BITFIELD:
+ case TYPE_FUNCTION:
+ return true;
+
+ case TYPE_ARRAY:
+ return type->array.size == NULL;
+
+ case TYPE_ATOMIC:
+ return type->atomic.akind == ATOMIC_TYPE_VOID;
+
+ case TYPE_POINTER:
+ case TYPE_BUILTIN:
+ case TYPE_ERROR:
+ return false;
+
+ case TYPE_TYPEDEF:
+ case TYPE_TYPEOF:
+ panic("is_type_incomplete called without typerefs skipped");
+ case TYPE_INVALID:
+ break;
+ }
+
+ panic("invalid type found");
+}
+
+static bool function_types_compatible(const function_type_t *func1,
+ const function_type_t *func2)
+{
+ const type_t* const ret1 = skip_typeref(func1->return_type);
+ const type_t* const ret2 = skip_typeref(func2->return_type);
+ if (!types_compatible(ret1, ret2))
+ return false;
+
+ /* can parameters be compared? */
+ if(func1->unspecified_parameters || func2->unspecified_parameters)
+ return true;
+
+ if(func1->variadic != func2->variadic)
+ return false;
+
+ /* TODO: handling of unspecified parameters not correct yet */
+
+ /* all argument types must be compatible */
+ function_parameter_t *parameter1 = func1->parameters;
+ function_parameter_t *parameter2 = func2->parameters;
+ for( ; parameter1 != NULL && parameter2 != NULL;
+ parameter1 = parameter1->next, parameter2 = parameter2->next) {
+ type_t *parameter1_type = skip_typeref(parameter1->type);
+ type_t *parameter2_type = skip_typeref(parameter2->type);
+
+ parameter1_type = get_unqualified_type(parameter1_type);
+ parameter2_type = get_unqualified_type(parameter2_type);
+
+ if(!types_compatible(parameter1_type, parameter2_type))
+ return false;
+ }
+ /* same number of arguments? */
+ if(parameter1 != NULL || parameter2 != NULL)
+ return false;
+
+ return true;
+}
+
+static bool array_types_compatible(const array_type_t *array1,
+ const array_type_t *array2)
+{
+ type_t *element_type1 = skip_typeref(array1->element_type);
+ type_t *element_type2 = skip_typeref(array2->element_type);
+ if(!types_compatible(element_type1, element_type2))
+ return false;
+
+ if(array1->size != NULL && array2->size != NULL) {
+ /* TODO: check if size expression evaluate to the same value
+ * if they are constant */
+ }
+
+ return true;
+}
+
+bool types_compatible(const type_t *type1, const type_t *type2)
+{
+ assert(!is_typeref(type1));
+ assert(!is_typeref(type2));
+
+ /* shortcut: the same type is always compatible */
+ if(type1 == type2)
+ return true;
+
+ if(type1->base.qualifiers != type2->base.qualifiers)
+ return false;
+ if(type1->kind != type2->kind)
+ return false;
+
+ switch(type1->kind) {
+ case TYPE_FUNCTION:
+ return function_types_compatible(&type1->function, &type2->function);
+ case TYPE_ATOMIC:
+ return type1->atomic.akind == type2->atomic.akind;
+ case TYPE_ARRAY:
+ return array_types_compatible(&type1->array, &type2->array);
+
+ case TYPE_POINTER: {
+ const type_t *const to1 = skip_typeref(type1->pointer.points_to);
+ const type_t *const to2 = skip_typeref(type2->pointer.points_to);
+ return types_compatible(to1, to2);
+ }
+
+ case TYPE_COMPOUND_STRUCT:
+ case TYPE_COMPOUND_UNION:
+ case TYPE_ENUM:
+ case TYPE_BUILTIN:
+ /* TODO: not implemented */
+ break;
+
+ case TYPE_BITFIELD:
+ /* not sure if this makes sense or is even needed, implement it if you
+ * really need it! */
+ panic("type compatibility check for bitfield type");
+
+ case TYPE_ERROR:
+ /* Hmm, the error type should be compatible to all other types */
+ return true;
+ case TYPE_INVALID:
+ panic("invalid type found in compatible types");
+ case TYPE_TYPEDEF:
+ case TYPE_TYPEOF:
+ panic("typerefs not skipped in compatible types?!?");
+ }
+
+ /* TODO: incomplete */
+ return false;
+}
+