Minor code reorganization

1 files changed, 2383 insertions, 0 deletions

diff --git a/src/check_type.cpp b/src/check_type.cpp
new file mode 100644
index 000000000..07f20b3af
--- /dev/null
+++ b/src/check_type.cpp
@@ -0,0 +1,2383 @@
+
+void populate_using_entity_map(Checker *c, AstNode *node, Type *t, Map<Entity *> *entity_map) {
+	t = base_type(type_deref(t));
+	gbString str = nullptr;
+	defer (gb_string_free(str));
+	if (node != nullptr) {
+		str = expr_to_string(node);
+	}
+
+	if (t->kind == Type_Struct) {
+		for_array(i, t->Struct.fields) {
+			Entity *f = t->Struct.fields[i];
+			GB_ASSERT(f->kind == Entity_Variable);
+			String name = f->token.string;
+			HashKey key = hash_string(name);
+			Entity **found = map_get(entity_map, key);
+			if (found != nullptr && name != "_") {
+				Entity *e = *found;
+				// TODO(bill): Better type error
+				if (str != nullptr) {
+					error(e->token, "`%.*s` is already declared in `%s`", LIT(name), str);
+				} else {
+					error(e->token, "`%.*s` is already declared`", LIT(name));
+				}
+			} else {
+				map_set(entity_map, key, f);
+				add_entity(c, c->context.scope, nullptr, f);
+				if (f->flags & EntityFlag_Using) {
+					populate_using_entity_map(c, node, f->type, entity_map);
+				}
+			}
+		}
+	}
+
+}
+
+
+void check_struct_field_decl(Checker *c, AstNode *decl, Array<Entity *> *fields, Map<Entity *> *entity_map, AstNode *struct_node, String context, bool allow_default_values) {
+	GB_ASSERT(fields != nullptr);
+	if (decl->kind == AstNode_WhenStmt) {
+		ast_node(ws, WhenStmt, decl);
+		Operand operand = {Addressing_Invalid};
+		check_expr(c, &operand, ws->cond);
+		if (operand.mode != Addressing_Constant || !is_type_boolean(operand.type)) {
+			error(ws->cond, "Non-constant boolean `when` condition");
+			return;
+		}
+		if (ws->body == nullptr || ws->body->kind != AstNode_BlockStmt) {
+			error(ws->cond, "Invalid body for `when` statement");
+			return;
+		}
+		if (operand.value.kind == ExactValue_Bool &&
+		    operand.value.value_bool) {
+			for_array(i, ws->body->BlockStmt.stmts) {
+				AstNode *stmt = ws->body->BlockStmt.stmts[i];
+				check_struct_field_decl(c, stmt, fields, entity_map, struct_node, context, allow_default_values);
+			}
+		} else if (ws->else_stmt) {
+			switch (ws->else_stmt->kind) {
+			case AstNode_BlockStmt:
+				for_array(i, ws->else_stmt->BlockStmt.stmts) {
+					AstNode *stmt = ws->else_stmt->BlockStmt.stmts[i];
+					check_struct_field_decl(c, stmt, fields, entity_map, struct_node, context, allow_default_values);
+				}
+				break;
+			case AstNode_WhenStmt:
+				check_struct_field_decl(c, ws->else_stmt, fields, entity_map, struct_node, context, allow_default_values);
+				break;
+			default:
+				error(ws->else_stmt, "Invalid `else` statement in `when` statement");
+				break;
+			}
+		}
+	}
+
+	if (decl->kind != AstNode_ValueDecl) {
+		return;
+	}
+
+
+	ast_node(vd, ValueDecl, decl);
+
+	if (!vd->is_mutable) return;
+
+	bool is_using = (vd->flags&VarDeclFlag_using) != 0;
+
+	if (is_using && vd->names.count > 1) {
+		error(vd->names[0], "Cannot apply `using` to more than one of the same type");
+		is_using = false;
+	}
+
+	bool arity_ok = check_arity_match(c, vd);
+
+	if (vd->values.count > 0 && !allow_default_values) {
+		error(vd->values[0], "Default values are not allowed within a %.*s", LIT(context));
+	}
+
+
+	Type *type = nullptr;
+	if (vd->type != nullptr) {
+		type = check_type(c, vd->type);
+	} else if (!allow_default_values) {
+		error(vd->names[0], "Expected a type for this field");
+		type = t_invalid;
+	}
+
+	if (type != nullptr) {
+		if (is_type_empty_union(type)) {
+			error(vd->names[0], "An empty union cannot be used as a field type in %.*s", LIT(context));
+			type = t_invalid;
+		}
+		if (!c->context.allow_polymorphic_types && is_type_polymorphic(base_type(type))) {
+			error(vd->names[0], "Invalid use of a polymorphic type in %.*s", LIT(context));
+			type = t_invalid;
+		}
+	}
+
+	Array<Operand> default_values = {};
+	defer (array_free(&default_values));
+	if (vd->values.count > 0 && allow_default_values) {
+		array_init(&default_values, heap_allocator(), 2*vd->values.count);
+
+		Type *type_hint = nullptr;
+		if (type != t_invalid && type != nullptr) {
+			type_hint = type;
+		}
+
+		for_array(i, vd->values) {
+			AstNode *v = vd->values[i];
+			Operand o = {};
+
+			check_expr_base(c, &o, v, type_hint);
+			check_not_tuple(c, &o);
+
+			if (o.mode == Addressing_NoValue) {
+				error_operand_no_value(&o);
+			} else {
+				if (o.mode == Addressing_Value && o.type->kind == Type_Tuple) {
+					// NOTE(bill): Tuples are not first class thus never named
+					for_array(index, o.type->Tuple.variables) {
+						Operand single = {Addressing_Value};
+						single.type    = o.type->Tuple.variables[index]->type;
+						single.expr    = v;
+						array_add(&default_values, single);
+					}
+				} else {
+					array_add(&default_values, o);
+				}
+			}
+		}
+	}
+
+
+	isize name_field_index = 0;
+	for_array(name_index, vd->names) {
+		AstNode *name = vd->names[name_index];
+		if (!ast_node_expect(name, AstNode_Ident)) {
+			return;
+		}
+
+		Token name_token = name->Ident.token;
+
+		Entity *e = make_entity_field(c->allocator, c->context.scope, name_token, type, is_using, cast(i32)fields->count);
+		e->identifier = name;
+
+		if (name_field_index < default_values.count) {
+			Operand a = default_values[name_field_index];
+			Operand b = default_values[name_field_index];
+			check_init_variable(c, e, &b, str_lit("struct field assignment"));
+			if (is_operand_nil(a)) {
+				e->Variable.default_is_nil = true;
+			} else if (is_operand_undef(a)) {
+				e->Variable.default_is_undef = true;
+			} else if (b.mode != Addressing_Constant) {
+				error(b.expr, "Default field value must be a constant");
+			} else if (is_type_any(e->type) || is_type_union(e->type)) {
+				gbString str = type_to_string(e->type);
+				error(b.expr, "A struct field of type `%s` cannot have a default value", str);
+				gb_string_free(str);
+			} else {
+				e->Variable.default_value = b.value;
+			}
+
+			name_field_index++;
+		}
+
+		GB_ASSERT(e->type != nullptr);
+		GB_ASSERT(is_type_typed(e->type));
+
+		if (is_blank_ident(name_token)) {
+			array_add(fields, e);
+		} else {
+			HashKey key = hash_string(name_token.string);
+			Entity **found = map_get(entity_map, key);
+			if (found != nullptr) {
+				Entity *e = *found;
+				// NOTE(bill): Scope checking already checks the declaration but in many cases, this can happen so why not?
+				// This may be a little janky but it's not really that much of a problem
+				error(name_token, "`%.*s` is already declared in this type", LIT(name_token.string));
+				error(e->token,   "\tpreviously declared");
+			} else {
+				map_set(entity_map, key, e);
+				array_add(fields, e);
+				add_entity(c, c->context.scope, name, e);
+			}
+			add_entity_use(c, name, e);
+		}
+
+	}
+
+	Entity *using_index_expr = nullptr;
+
+	if (is_using && fields->count > 0) {
+		Type *first_type = (*fields)[fields->count-1]->type;
+		Type *t = base_type(type_deref(first_type));
+		if (!is_type_struct(t) && !is_type_raw_union(t) && !is_type_bit_field(t) &&
+		    vd->names.count >= 1 &&
+		    vd->names[0]->kind == AstNode_Ident) {
+			Token name_token = vd->names[0]->Ident.token;
+			if (is_type_indexable(t)) {
+				bool ok = true;
+				for_array(emi, entity_map->entries) {
+					Entity *e = entity_map->entries[emi].value;
+					if (e->kind == Entity_Variable && e->flags & EntityFlag_Using) {
+						if (is_type_indexable(e->type)) {
+							if (e->identifier != vd->names[0]) {
+								ok = false;
+								using_index_expr = e;
+								break;
+							}
+						}
+					}
+				}
+				if (ok) {
+					using_index_expr = (*fields)[fields->count-1];
+				} else {
+					(*fields)[fields->count-1]->flags &= ~EntityFlag_Using;
+					error(name_token, "Previous `using` for an index expression `%.*s`", LIT(name_token.string));
+				}
+			} else {
+				gbString type_str = type_to_string(first_type);
+				error(name_token, "`using` cannot be applied to the field `%.*s` of type `%s`", LIT(name_token.string), type_str);
+				gb_string_free(type_str);
+				return;
+			}
+		}
+
+		populate_using_entity_map(c, struct_node, type, entity_map);
+	}
+}
+
+// Returns filled field_count
+Array<Entity *> check_struct_fields(Checker *c, AstNode *node, Array<AstNode *> params,
+                                    isize init_field_capacity, Type *named_type, String context) {
+	gbTempArenaMemory tmp = gb_temp_arena_memory_begin(&c->tmp_arena);
+	defer (gb_temp_arena_memory_end(tmp));
+
+	Array<Entity *> fields = {};
+	array_init(&fields, heap_allocator(), init_field_capacity);
+
+	Map<Entity *> entity_map = {};
+	map_init(&entity_map, c->tmp_allocator, 2*init_field_capacity);
+
+
+	GB_ASSERT(node->kind == AstNode_StructType);
+
+	isize variable_count = 0;
+	for_array(i, params) {
+		AstNode *field = params[i];
+		if (ast_node_expect(field, AstNode_Field)) {
+			ast_node(f, Field, field);
+			variable_count += gb_max(f->names.count, 1);
+		}
+	}
+
+	i32 field_src_index = 0;
+	for_array(i, params) {
+		AstNode *param = params[i];
+		if (param->kind != AstNode_Field) {
+			continue;
+		}
+		ast_node(p, Field, param);
+		AstNode *type_expr = p->type;
+		Type *type = nullptr;
+		AstNode *default_value = unparen_expr(p->default_value);
+		ExactValue value = {};
+		bool default_is_nil = false;
+		bool detemine_type_from_operand = false;
+
+
+		if (type_expr == nullptr) {
+			Operand o = {};
+			check_expr_or_type(c, &o, default_value);
+			if (is_operand_nil(o)) {
+				default_is_nil = true;
+			} else if (o.mode != Addressing_Constant) {
+				if (default_value->kind == AstNode_ProcLit) {
+					if (named_type != nullptr) {
+						value = exact_value_procedure(default_value);
+					} else {
+						error(default_value, "A procedure literal cannot be a default value in an anonymous structure");
+					}
+				} else {
+					Entity *e = nullptr;
+					if (o.mode == Addressing_Value && is_type_proc(o.type)) {
+						Operand x = {};
+						if (default_value->kind == AstNode_Ident) {
+							e = check_ident(c, &x, default_value, nullptr, nullptr, false);
+						} else if (default_value->kind == AstNode_SelectorExpr) {
+							e = check_selector(c, &x, default_value, nullptr);
+						}
+					}
+
+					if (e != nullptr && e->kind == Entity_Procedure) {
+						value = exact_value_procedure(e->identifier);
+						add_entity_use(c, e->identifier, e);
+					} else {
+						error(default_value, "Default parameter must be a constant");
+					}
+				}
+			} else {
+				value = o.value;
+			}
+
+			type = default_type(o.type);
+		} else {
+			type = check_type(c, type_expr);
+
+			if (default_value != nullptr) {
+				Operand o = {};
+				check_expr_with_type_hint(c, &o, default_value, type);
+
+				if (is_operand_nil(o)) {
+					default_is_nil = true;
+				} else if (o.mode != Addressing_Constant) {
+					if (default_value->kind == AstNode_ProcLit) {
+						if (named_type != nullptr) {
+							value = exact_value_procedure(default_value);
+						} else {
+							error(default_value, "A procedure literal cannot be a default value in an anonymous structure");
+						}
+					} else {
+						Entity *e = nullptr;
+						if (o.mode == Addressing_Value && is_type_proc(o.type)) {
+							Operand x = {};
+							if (default_value->kind == AstNode_Ident) {
+								e = check_ident(c, &x, default_value, nullptr, nullptr, false);
+							} else if (default_value->kind == AstNode_SelectorExpr) {
+								e = check_selector(c, &x, default_value, nullptr);
+							}
+						}
+
+						if (e != nullptr && e->kind == Entity_Procedure) {
+							value = exact_value_procedure(e->identifier);
+							add_entity_use(c, e->identifier, e);
+						} else {
+							error(default_value, "Default parameter must be a constant");
+						}
+					}
+				} else {
+					value = o.value;
+				}
+
+				check_is_assignable_to(c, &o, type);
+			}
+
+			if (is_type_polymorphic(type)) {
+				type = nullptr;
+			}
+		}
+		if (type == nullptr) {
+			error(params[i], "Invalid parameter type");
+			type = t_invalid;
+		}
+		if (is_type_untyped(type)) {
+			if (is_type_untyped_undef(type)) {
+				error(params[i], "Cannot determine parameter type from ---");
+			} else {
+				error(params[i], "Cannot determine parameter type from a nil");
+			}
+			type = t_invalid;
+		}
+		if (is_type_empty_union(type)) {
+			gbString str = type_to_string(type);
+			error(params[i], "Invalid use of an empty union `%s`", str);
+			gb_string_free(str);
+			type = t_invalid;
+		}
+
+		bool is_using = (p->flags&FieldFlag_using) != 0;
+
+		for_array(j, p->names) {
+			AstNode *name = p->names[j];
+			if (!ast_node_expect(name, AstNode_Ident)) {
+				continue;
+			}
+
+			Token name_token = name->Ident.token;
+
+			Entity *field = nullptr;
+			field = make_entity_field(c->allocator, c->context.scope, name_token, type, is_using, field_src_index);
+			field->Variable.default_value = value;
+			field->Variable.default_is_nil = default_is_nil;
+
+			add_entity(c, c->context.scope, name, field);
+			array_add(&fields, field);
+
+			field_src_index += 1;
+		}
+
+		Entity *using_index_expr = nullptr;
+
+		if (is_using && p->names.count > 0) {
+			Type *first_type = fields[fields.count-1]->type;
+			Type *t = base_type(type_deref(first_type));
+
+			if (!is_type_struct(t) && !is_type_raw_union(t) && !is_type_bit_field(t) &&
+			    p->names.count >= 1 &&
+			    p->names[0]->kind == AstNode_Ident) {
+				Token name_token = p->names[0]->Ident.token;
+				if (is_type_indexable(t)) {
+					bool ok = true;
+					for_array(emi, entity_map.entries) {
+						Entity *e = entity_map.entries[emi].value;
+						if (e->kind == Entity_Variable && e->flags & EntityFlag_Using) {
+							if (is_type_indexable(e->type)) {
+								if (e->identifier != p->names[0]) {
+									ok = false;
+									using_index_expr = e;
+									break;
+								}
+							}
+						}
+					}
+					if (ok) {
+						using_index_expr = fields[fields.count-1];
+					} else {
+						fields[fields.count-1]->flags &= ~EntityFlag_Using;
+						error(name_token, "Previous `using` for an index expression `%.*s`", LIT(name_token.string));
+					}
+				} else {
+					gbString type_str = type_to_string(first_type);
+					error(name_token, "`using` cannot be applied to the field `%.*s` of type `%s`", LIT(name_token.string), type_str);
+					gb_string_free(type_str);
+					continue;
+				}
+			}
+
+			populate_using_entity_map(c, node, type, &entity_map);
+		}
+	}
+
+	// for_array(decl_index, params) {
+		// check_struct_field_decl(c, params[decl_index], &fields, &entity_map, node, context, context == "struct");
+	// }
+
+
+	return fields;
+}
+
+
+// TODO(bill): Cleanup struct field reordering
+// TODO(bill): Inline sorting procedure?
+gb_global gbAllocator   __checker_allocator = {};
+
+GB_COMPARE_PROC(cmp_reorder_struct_fields) {
+	// Rule:
+	// `using` over non-`using`
+	// Biggest to smallest alignment
+	// if same alignment: biggest to smallest size
+	// if same size: order by source order
+	Entity *x = *(Entity **)a;
+	Entity *y = *(Entity **)b;
+	GB_ASSERT(x != nullptr);
+	GB_ASSERT(y != nullptr);
+	GB_ASSERT(x->kind == Entity_Variable);
+	GB_ASSERT(y->kind == Entity_Variable);
+	bool xu = (x->flags & EntityFlag_Using) != 0;
+	bool yu = (y->flags & EntityFlag_Using) != 0;
+	i64 xa = type_align_of(__checker_allocator, x->type);
+	i64 ya = type_align_of(__checker_allocator, y->type);
+	i64 xs = type_size_of(__checker_allocator, x->type);
+	i64 ys = type_size_of(__checker_allocator, y->type);
+
+	if (xu != yu) {
+		return xu ? -1 : +1;
+	}
+
+	if (xa != ya) {
+		return xa > ya ? -1 : xa < ya;
+	}
+	if (xs != ys) {
+		return xs > ys ? -1 : xs < ys;
+	}
+	i32 diff = x->Variable.field_index - y->Variable.field_index;
+	return diff < 0 ? -1 : diff > 0;
+}
+
+Entity *make_names_field_for_struct(Checker *c, Scope *scope) {
+	Entity *e = make_entity_field(c->allocator, scope,
+		make_token_ident(str_lit("names")), t_string_slice, false, 0);
+	e->Variable.is_immutable = true;
+	e->flags |= EntityFlag_TypeField;
+	return e;
+}
+
+bool check_custom_align(Checker *c, AstNode *node, i64 *align_) {
+	GB_ASSERT(align_ != nullptr);
+	Operand o = {};
+	check_expr(c, &o, node);
+	if (o.mode != Addressing_Constant) {
+		if (o.mode != Addressing_Invalid) {
+			error(node, "#align must be a constant");
+		}
+		return false;
+	}
+
+	Type *type = base_type(o.type);
+	if (is_type_untyped(type) || is_type_integer(type)) {
+		if (o.value.kind == ExactValue_Integer) {
+			i64 align = i128_to_i64(o.value.value_integer);
+			if (align < 1 || !gb_is_power_of_two(align)) {
+				error(node, "#align must be a power of 2, got %lld", align);
+				return false;
+			}
+
+			// NOTE(bill): Success!!!
+			i64 custom_align = gb_clamp(align, 1, build_context.max_align);
+			if (custom_align < align) {
+				warning(node, "Custom alignment has been clamped to %lld from %lld", align, custom_align);
+			}
+			*align_ = custom_align;
+			return true;
+		}
+	}
+
+	error(node, "#align must be an integer");
+	return false;
+}
+
+
+Entity *find_polymorphic_struct_entity(Checker *c, Type *original_type, isize param_count, Array<Operand> ordered_operands) {
+	auto *found_gen_types = map_get(&c->info.gen_types, hash_pointer(original_type));
+
+	if (found_gen_types != nullptr) {
+		for_array(i, *found_gen_types) {
+			Entity *e = (*found_gen_types)[i];
+			Type *t = base_type(e->type);
+			TypeTuple *tuple = &t->Struct.polymorphic_params->Tuple;
+			bool ok = true;
+			GB_ASSERT(param_count == tuple->variables.count);
+			for (isize j = 0; j < param_count; j++) {
+				Entity *p = tuple->variables[j];
+				Operand o = ordered_operands[j];
+				if (p->kind == Entity_TypeName) {
+					if (is_type_polymorphic(o.type)) {
+						// NOTE(bill): Do not add polymorphic version to the gen_types
+						ok = false;
+					}
+					if (!are_types_identical(o.type, p->type)) {
+						ok = false;
+					}
+				} else if (p->kind == Entity_Constant) {
+					if (!are_types_identical(o.type, p->type)) {
+						ok = false;
+					}
+					if (!compare_exact_values(Token_CmpEq, o.value, p->Constant.value)) {
+						ok = false;
+					}
+				} else {
+					GB_PANIC("Unknown entity kind");
+				}
+			}
+			if (ok) {
+				return e;
+			}
+		}
+	}
+	return nullptr;
+}
+
+
+void add_polymorphic_struct_entity(Checker *c, AstNode *node, Type *named_type, Type *original_type) {
+	GB_ASSERT(is_type_named(named_type));
+	gbAllocator a = heap_allocator();
+	Scope *s = c->context.scope->parent;
+
+	Entity *e = nullptr;
+	{
+		Token token = ast_node_token(node);
+		token.kind = Token_String;
+		token.string = named_type->Named.name;
+
+		AstNode *node = gb_alloc_item(a, AstNode);
+		node->kind = AstNode_Ident;
+		node->Ident.token = token;
+
+		e = make_entity_type_name(a, s, token, named_type);
+		add_entity_use(c, node, e);
+	}
+
+	named_type->Named.type_name = e;
+
+	auto *found_gen_types = map_get(&c->info.gen_types, hash_pointer(original_type));
+	if (found_gen_types) {
+		array_add(found_gen_types, e);
+	} else {
+		Array<Entity *> array = {};
+		array_init(&array, heap_allocator());
+		array_add(&array, e);
+		map_set(&c->info.gen_types, hash_pointer(original_type), array);
+	}
+}
+
+void check_struct_type(Checker *c, Type *struct_type, AstNode *node, Array<Operand> *poly_operands, Type *named_type, Type *original_type_for_poly) {
+	GB_ASSERT(is_type_struct(struct_type));
+	ast_node(st, StructType, node);
+
+	String context = str_lit("struct");
+
+	isize min_field_count = 0;
+	for_array(field_index, st->fields) {
+	AstNode *field = st->fields[field_index];
+		switch (field->kind) {
+		case_ast_node(f, ValueDecl, field);
+			min_field_count += f->names.count;
+		case_end;
+		}
+	}
+	struct_type->Struct.names = make_names_field_for_struct(c, c->context.scope);
+
+	if (st->is_raw_union) {
+		struct_type->Struct.is_raw_union = true;
+		context = str_lit("struct #raw_union");
+	}
+
+	Type *polymorphic_params     = nullptr;
+	bool is_polymorphic          = false;
+	bool can_check_fields        = true;
+	bool is_poly_specialized     = false;
+
+	if (st->polymorphic_params != nullptr) {
+		ast_node(field_list, FieldList, st->polymorphic_params);
+		Array<AstNode *> params = field_list->list;
+		if (params.count != 0) {
+			isize variable_count = 0;
+			for_array(i, params) {
+				AstNode *field = params[i];
+				if (ast_node_expect(field, AstNode_Field)) {
+					ast_node(f, Field, field);
+					variable_count += gb_max(f->names.count, 1);
+				}
+			}
+
+			Array<Entity *> entities = {};
+			array_init(&entities, c->allocator, variable_count);
+
+			for_array(i, params) {
+				AstNode *param = params[i];
+				if (param->kind != AstNode_Field) {
+					continue;
+				}
+				ast_node(p, Field, param);
+				AstNode *type_expr = p->type;
+				Type *type = nullptr;
+				bool is_type_param = false;
+				bool is_type_polymorphic_type = false;
+				if (type_expr == nullptr) {
+					error(param, "Expected a type for this parameter");
+					continue;
+				}
+				if (type_expr->kind == AstNode_Ellipsis) {
+					type_expr = type_expr->Ellipsis.expr;
+					error(param, "A polymorphic parameter cannot be variadic");
+				}
+				if (type_expr->kind == AstNode_TypeType) {
+					is_type_param = true;
+					Type *specialization = nullptr;
+					if (type_expr->TypeType.specialization != nullptr) {
+						AstNode *s = type_expr->TypeType.specialization;
+						specialization = check_type(c, s);
+						if (false && !is_type_polymorphic_struct(specialization)) {
+							gbString str = type_to_string(specialization);
+							defer (gb_string_free(str));
+							error(s, "Expected a polymorphic struct, got %s", str);
+							specialization = nullptr;
+						}
+					}
+					type = make_type_generic(c->allocator, 0, str_lit(""), specialization);
+				} else {
+					type = check_type(c, type_expr);
+					if (is_type_polymorphic(type)) {
+						is_type_polymorphic_type = true;
+					}
+				}
+
+				if (type == nullptr) {
+					error(params[i], "Invalid parameter type");
+					type = t_invalid;
+				}
+				if (is_type_untyped(type)) {
+					if (is_type_untyped_undef(type)) {
+						error(params[i], "Cannot determine parameter type from ---");
+					} else {
+						error(params[i], "Cannot determine parameter type from a nil");
+					}
+					type = t_invalid;
+				}
+
+				if (is_type_polymorphic_type) {
+					gbString str = type_to_string(type);
+					error(params[i], "Parameter types cannot be polymorphic, got %s", str);
+					gb_string_free(str);
+					type = t_invalid;
+				}
+
+				if (!is_type_param && !is_type_constant_type(type)) {
+					gbString str = type_to_string(type);
+					error(params[i], "A parameter must be a valid constant type, got %s", str);
+					gb_string_free(str);
+				}
+
+				Scope *scope = c->context.scope;
+				for_array(j, p->names) {
+					AstNode *name = p->names[j];
+					if (!ast_node_expect(name, AstNode_Ident)) {
+						continue;
+					}
+					Entity *e = nullptr;
+
+					Token token = name->Ident.token;
+
+					if (poly_operands != nullptr) {
+						Operand operand = (*poly_operands)[entities.count];
+						if (is_type_param) {
+							GB_ASSERT(operand.mode == Addressing_Type ||
+							          operand.mode == Addressing_Invalid);
+							if (is_type_polymorphic(base_type(operand.type))) {
+								is_polymorphic = true;
+								can_check_fields = false;
+							}
+							e = make_entity_type_name(c->allocator, scope, token, operand.type);
+							e->TypeName.is_type_alias = true;
+						} else {
+							GB_ASSERT(operand.mode == Addressing_Constant);
+							e = make_entity_constant(c->allocator, scope, token, operand.type, operand.value);
+						}
+					} else {
+						if (is_type_param) {
+							e = make_entity_type_name(c->allocator, scope, token, type);
+							e->TypeName.is_type_alias = true;
+						} else {
+							e = make_entity_constant(c->allocator, scope, token, type, empty_exact_value);
+						}
+					}
+
+					add_entity(c, scope, name, e);
+					array_add(&entities, e);
+				}
+			}
+
+			if (entities.count > 0) {
+				Type *tuple = make_type_tuple(c->allocator);
+				tuple->Tuple.variables = entities;
+				polymorphic_params = tuple;
+			}
+		}
+
+		if (original_type_for_poly != nullptr) {
+			GB_ASSERT(named_type != nullptr);
+			add_polymorphic_struct_entity(c, node, named_type, original_type_for_poly);
+		}
+	}
+
+	if (!is_polymorphic) {
+		is_polymorphic = polymorphic_params != nullptr && poly_operands == nullptr;
+	}
+	if (poly_operands != nullptr) {
+		is_poly_specialized = true;
+		for (isize i = 0; i < poly_operands->count; i++) {
+			Operand o = (*poly_operands)[i];
+			if (is_type_polymorphic(o.type)) {
+				is_poly_specialized = false;
+				break;
+			}
+		}
+	}
+
+	struct_type->Struct.scope                   = c->context.scope;
+	struct_type->Struct.is_packed               = st->is_packed;
+	struct_type->Struct.is_ordered              = st->is_ordered;
+	struct_type->Struct.polymorphic_params      = polymorphic_params;
+	struct_type->Struct.is_polymorphic          = is_polymorphic;
+	struct_type->Struct.is_poly_specialized     = is_poly_specialized;
+
+	Array<Entity *> fields = {};
+
+	if (!is_polymorphic) {
+		fields = check_struct_fields(c, node, st->fields, min_field_count, named_type, context);
+	}
+
+	struct_type->Struct.fields              = fields;
+	struct_type->Struct.fields_in_src_order = fields;
+
+	for_array(i, fields) {
+		Entity *f = fields[i];
+		if (f->kind == Entity_Variable) {
+			if (f->Variable.default_value.kind == ExactValue_Procedure) {
+				struct_type->Struct.has_proc_default_values = true;
+				break;
+			}
+		}
+	}
+
+
+	if (!struct_type->Struct.is_raw_union) {
+		type_set_offsets(c->allocator, struct_type);
+
+		if (!struct_type->failure && !st->is_packed && !st->is_ordered) {
+			struct_type->failure = false;
+			struct_type->Struct.are_offsets_set = false;
+			gb_zero_item(&struct_type->Struct.offsets);
+			// NOTE(bill): Reorder fields for reduced size/performance
+
+			Array<Entity *> reordered_fields = {};
+			array_init_count(&reordered_fields, c->allocator, fields.count);
+			for_array(i, reordered_fields) {
+				reordered_fields[i] = struct_type->Struct.fields_in_src_order[i];
+			}
+
+			// NOTE(bill): Hacky thing
+			// TODO(bill): Probably make an inline sorting procedure rather than use global variables
+			__checker_allocator = c->allocator;
+			// NOTE(bill): compound literal order must match source not layout
+			gb_sort_array(reordered_fields.data, fields.count, cmp_reorder_struct_fields);
+
+			for_array(i, fields) {
+				reordered_fields[i]->Variable.field_index = cast(i32)i;
+			}
+
+			struct_type->Struct.fields = reordered_fields;
+		}
+
+		type_set_offsets(c->allocator, struct_type);
+	}
+
+
+	if (st->align != nullptr) {
+		if (st->is_packed) {
+			syntax_error(st->align, "`#align` cannot be applied with `#packed`");
+			return;
+		}
+		i64 custom_align = 1;
+		if (check_custom_align(c, st->align, &custom_align)) {
+			struct_type->Struct.custom_align = custom_align;
+		}
+	}
+}
+void check_union_type(Checker *c, Type *union_type, AstNode *node) {
+	GB_ASSERT(is_type_union(union_type));
+	ast_node(ut, UnionType, node);
+
+	isize variant_count = ut->variants.count;
+
+	gbTempArenaMemory tmp = gb_temp_arena_memory_begin(&c->tmp_arena);
+	defer (gb_temp_arena_memory_end(tmp));
+
+	Entity *using_index_expr = nullptr;
+
+	Array<Type *> variants = {};
+	array_init(&variants, c->allocator, variant_count);
+
+	union_type->Union.scope = c->context.scope;
+
+	for_array(i, ut->variants) {
+		AstNode *node = ut->variants[i];
+		Type *t = check_type(c, node);
+		if (t != nullptr && t != t_invalid) {
+			bool ok = true;
+			t = default_type(t);
+			if (is_type_untyped(t) || is_type_empty_union(t)) {
+				ok = false;
+				gbString str = type_to_string(t);
+				error(node, "Invalid variant type in union `%s`", str);
+				gb_string_free(str);
+			} else {
+				for_array(j, variants) {
+					if (are_types_identical(t, variants[j])) {
+						ok = false;
+						gbString str = type_to_string(t);
+						error(node, "Duplicate variant type `%s`", str);
+						gb_string_free(str);
+						break;
+					}
+				}
+			}
+			if (ok) {
+				array_add(&variants, t);
+			}
+		}
+	}
+
+	union_type->Union.variants = variants;
+
+	if (ut->align != nullptr) {
+		i64 custom_align = 1;
+		if (check_custom_align(c, ut->align, &custom_align)) {
+			if (variants.count == 0) {
+				error(ut->align, "An empty union cannot have a custom alignment");
+			} else {
+				union_type->Union.custom_align = custom_align;
+			}
+		}
+	}
+}
+
+void check_enum_type(Checker *c, Type *enum_type, Type *named_type, AstNode *node) {
+	ast_node(et, EnumType, node);
+	GB_ASSERT(is_type_enum(enum_type));
+
+	gbTempArenaMemory tmp = gb_temp_arena_memory_begin(&c->tmp_arena);
+	defer (gb_temp_arena_memory_end(tmp));
+
+	Type *base_type = t_int;
+	if (et->base_type != nullptr) {
+		base_type = check_type(c, et->base_type);
+	}
+
+	if (base_type == nullptr || !(is_type_integer(base_type) || is_type_float(base_type))) {
+		error(node, "Base type for enumeration must be numeric");
+		return;
+	}
+	if (is_type_enum(base_type)) {
+		error(node, "Base type for enumeration cannot be another enumeration");
+		return;
+	}
+
+	// NOTE(bill): Must be up here for the `check_init_constant` system
+	enum_type->Enum.base_type = base_type;
+
+	Map<Entity *> entity_map = {}; // Key: String
+	map_init(&entity_map, c->tmp_allocator, 2*(et->fields.count));
+
+	Array<Entity *> fields = {};
+	array_init(&fields, c->allocator, et->fields.count);
+
+	Type *constant_type = enum_type;
+	if (named_type != nullptr) {
+		constant_type = named_type;
+	}
+
+	ExactValue iota = exact_value_i64(-1);
+	ExactValue min_value = exact_value_i64(0);
+	ExactValue max_value = exact_value_i64(0);
+
+	for_array(i, et->fields) {
+		AstNode *field = et->fields[i];
+		AstNode *ident = nullptr;
+		AstNode *init = nullptr;
+		if (field->kind == AstNode_FieldValue) {
+			ast_node(fv, FieldValue, field);
+			if (fv->field == nullptr || fv->field->kind != AstNode_Ident) {
+				error(field, "An enum field's name must be an identifier");
+				continue;
+			}
+			ident = fv->field;
+			init = fv->value;
+		} else if (field->kind == AstNode_Ident) {
+			ident = field;
+		} else {
+			error(field, "An enum field's name must be an identifier");
+			continue;
+		}
+		String name = ident->Ident.token.string;
+
+		if (init != nullptr) {
+			Operand o = {};
+			check_expr(c, &o, init);
+			if (o.mode != Addressing_Constant) {
+				error(init, "Enumeration value must be a constant");
+				o.mode = Addressing_Invalid;
+			}
+			if (o.mode != Addressing_Invalid) {
+				check_assignment(c, &o, constant_type, str_lit("enumeration"));
+			}
+			if (o.mode != Addressing_Invalid) {
+				iota = o.value;
+			} else {
+				iota = exact_binary_operator_value(Token_Add, iota, exact_value_i64(1));
+			}
+		} else {
+			iota = exact_binary_operator_value(Token_Add, iota, exact_value_i64(1));
+		}
+
+
+		// NOTE(bill): Skip blank identifiers
+		if (is_blank_ident(name)) {
+			continue;
+		} else if (name == "count") {
+			error(field, "`count` is a reserved identifier for enumerations");
+			continue;
+		} else if (name == "min_value") {
+			error(field, "`min_value` is a reserved identifier for enumerations");
+			continue;
+		} else if (name == "max_value") {
+			error(field, "`max_value` is a reserved identifier for enumerations");
+			continue;
+		} else if (name == "names") {
+			error(field, "`names` is a reserved identifier for enumerations");
+			continue;
+		}/*  else if (name == "base_type") {
+			error(field, "`base_type` is a reserved identifier for enumerations");
+			continue;
+		} */
+
+		if (compare_exact_values(Token_Gt, min_value, iota)) {
+			min_value = iota;
+		}
+		if (compare_exact_values(Token_Lt, max_value, iota)) {
+			max_value = iota;
+		}
+
+		Entity *e = make_entity_constant(c->allocator, c->context.scope, ident->Ident.token, constant_type, iota);
+		e->identifier = ident;
+		e->flags |= EntityFlag_Visited;
+
+		HashKey key = hash_string(name);
+		if (map_get(&entity_map, key) != nullptr) {
+			error(ident, "`%.*s` is already declared in this enumeration", LIT(name));
+		} else {
+			map_set(&entity_map, key, e);
+			add_entity(c, c->context.scope, nullptr, e);
+			array_add(&fields, e);
+			add_entity_use(c, field, e);
+		}
+	}
+	GB_ASSERT(fields.count <= et->fields.count);
+
+
+	enum_type->Enum.fields      = fields.data;
+	enum_type->Enum.field_count = cast(i32)fields.count;
+
+	enum_type->Enum.count = make_entity_constant(c->allocator, c->context.scope,
+		make_token_ident(str_lit("count")), t_int, exact_value_i64(fields.count));
+	enum_type->Enum.min_value = make_entity_constant(c->allocator, c->context.scope,
+		make_token_ident(str_lit("min_value")), constant_type, min_value);
+	enum_type->Enum.max_value = make_entity_constant(c->allocator, c->context.scope,
+		make_token_ident(str_lit("max_value")), constant_type, max_value);
+
+	enum_type->Enum.names = make_names_field_for_struct(c, c->context.scope);
+}
+
+
+void check_bit_field_type(Checker *c, Type *bit_field_type, AstNode *node) {
+	ast_node(bft, BitFieldType, node);
+	GB_ASSERT(is_type_bit_field(bit_field_type));
+
+	gbTempArenaMemory tmp = gb_temp_arena_memory_begin(&c->tmp_arena);
+	defer (gb_temp_arena_memory_end(tmp));
+
+	Map<Entity *> entity_map = {}; // Key: String
+	map_init(&entity_map, c->tmp_allocator, 2*(bft->fields.count));
+
+	isize field_count = 0;
+	Entity **fields  = gb_alloc_array(c->allocator, Entity *, bft->fields.count);
+	u32 *    sizes   = gb_alloc_array(c->allocator, u32,      bft->fields.count);
+	u32 *    offsets = gb_alloc_array(c->allocator, u32,      bft->fields.count);
+
+	u32 curr_offset = 0;
+	for_array(i, bft->fields) {
+		AstNode *field = bft->fields[i];
+		GB_ASSERT(field->kind == AstNode_FieldValue);
+		AstNode *ident = field->FieldValue.field;
+		AstNode *value = field->FieldValue.value;
+
+		if (ident->kind != AstNode_Ident) {
+			error(field, "A bit field value's name must be an identifier");
+			continue;
+		}
+		String name = ident->Ident.token.string;
+
+		Operand o = {};
+		check_expr(c, &o, value);
+		if (o.mode != Addressing_Constant) {
+			error(value, "Bit field bit size must be a constant");
+			continue;
+		}
+		ExactValue v = exact_value_to_integer(o.value);
+		if (v.kind != ExactValue_Integer) {
+			error(value, "Bit field bit size must be a constant integer");
+			continue;
+		}
+		i64 bits = i128_to_i64(v.value_integer);
+		if (bits < 0 || bits > 128) {
+			error(value, "Bit field's bit size must be within the range 1..<128, got %lld", cast(long long)bits);
+			continue;
+		}
+
+		Type *value_type = make_type_bit_field_value(c->allocator, cast(i32)bits);
+		Entity *e = make_entity_variable(c->allocator, bit_field_type->BitField.scope, ident->Ident.token, value_type, false);
+		e->identifier = ident;
+		e->flags |= EntityFlag_BitFieldValue;
+
+		HashKey key = hash_string(name);
+		if (!is_blank_ident(name) &&
+		    map_get(&entity_map, key) != nullptr) {
+			error(ident, "`%.*s` is already declared in this bit field", LIT(name));
+		} else {
+			map_set(&entity_map, key, e);
+			add_entity(c, c->context.scope, nullptr, e);
+			add_entity_use(c, field, e);
+
+			fields [field_count] = e;
+			offsets[field_count] = curr_offset;
+			sizes  [field_count] = cast(i32)bits;
+			field_count++;
+
+			curr_offset += cast(i32)bits;
+		}
+	}
+	GB_ASSERT(field_count <= bft->fields.count);
+
+	bit_field_type->BitField.fields      = fields;
+	bit_field_type->BitField.field_count = cast(i32)field_count;
+	bit_field_type->BitField.sizes       = sizes;
+	bit_field_type->BitField.offsets     = offsets;
+
+
+	if (bft->align != nullptr) {
+		i64 custom_align = 1;
+		if (check_custom_align(c, bft->align, &custom_align)) {
+			bit_field_type->BitField.custom_align = custom_align;
+		}
+	}
+}
+
+
+bool check_type_specialization_to(Checker *c, Type *specialization, Type *type, bool compound, bool modify_type) {
+	if (type == nullptr ||
+	    type == t_invalid) {
+		return true;
+	}
+
+	Type *t = base_type(type);
+	Type *s = base_type(specialization);
+	if (t->kind != s->kind) {
+		return false;
+	}
+	// gb_printf_err("#1 %s %s\n", type_to_string(type), type_to_string(specialization));
+	if (t->kind == Type_Struct) {
+		if (t->Struct.polymorphic_parent == specialization) {
+			return true;
+		}
+
+		if (t->Struct.polymorphic_parent == s->Struct.polymorphic_parent &&
+		    s->Struct.polymorphic_params != nullptr &&
+		    t->Struct.polymorphic_params != nullptr) {
+
+			TypeTuple *s_tuple = &s->Struct.polymorphic_params->Tuple;
+			TypeTuple *t_tuple = &t->Struct.polymorphic_params->Tuple;
+			GB_ASSERT(t_tuple->variables.count == s_tuple->variables.count);
+			for_array(i, s_tuple->variables) {
+				Entity *s_e = s_tuple->variables[i];
+				Entity *t_e = t_tuple->variables[i];
+				Type *st = s_e->type;
+				Type *tt = t_e->type;
+				bool ok = is_polymorphic_type_assignable(c, st, tt, true, modify_type);
+			}
+
+			if (modify_type) {
+				// NOTE(bill): This is needed in order to change the actual type but still have the types defined within it
+				gb_memmove(specialization, type, gb_size_of(Type));
+			}
+
+			return true;
+		}
+	}
+
+	if (specialization->kind == Type_Named &&
+	    type->kind != Type_Named) {
+		return false;
+	}
+	if (is_polymorphic_type_assignable(c, base_type(specialization), base_type(type), compound, modify_type)) {
+		return true;
+	}
+
+	return false;
+}
+
+
+Type *determine_type_from_polymorphic(Checker *c, Type *poly_type, Operand operand) {
+	bool modify_type = !c->context.no_polymorphic_errors;
+	if (!is_operand_value(operand)) {
+		if (modify_type) {
+			error(operand.expr, "Cannot determine polymorphic type from parameter");
+		}
+		return t_invalid;
+	}
+	if (is_polymorphic_type_assignable(c, poly_type, operand.type, false, modify_type)) {
+		return poly_type;
+	}
+	if (modify_type) {
+		gbString pts = type_to_string(poly_type);
+		gbString ots = type_to_string(operand.type);
+		defer (gb_string_free(pts));
+		defer (gb_string_free(ots));
+		error(operand.expr, "Cannot determine polymorphic type from parameter: `%s` to `%s`", ots, pts);
+	}
+	return t_invalid;
+}
+
+
+Type *check_get_params(Checker *c, Scope *scope, AstNode *_params, bool *is_variadic_, bool *success_, isize *specialization_count_, Array<Operand> *operands) {
+	if (_params == nullptr) {
+		return nullptr;
+	}
+
+	bool allow_polymorphic_types = c->context.allow_polymorphic_types;
+
+	bool success = true;
+	ast_node(field_list, FieldList, _params);
+	Array<AstNode *> params = field_list->list;
+
+	if (params.count == 0) {
+		if (success_) *success_ = success;
+		return nullptr;
+	}
+
+
+
+	isize variable_count = 0;
+	for_array(i, params) {
+		AstNode *field = params[i];
+		if (ast_node_expect(field, AstNode_Field)) {
+			ast_node(f, Field, field);
+			variable_count += gb_max(f->names.count, 1);
+		}
+	}
+	isize min_variable_count = variable_count;
+	for (isize i = params.count-1; i >= 0; i--) {
+		AstNode *field = params[i];
+		if (field->kind == AstNode_Field) {
+			ast_node(f, Field, field);
+			if (f->default_value == nullptr)  {
+				break;
+			}
+			min_variable_count--;
+		}
+	}
+
+
+	bool is_variadic = false;
+	bool is_c_vararg = false;
+	Array<Entity *> variables = {};
+	array_init(&variables, c->allocator, variable_count);
+	for_array(i, params) {
+		AstNode *param = params[i];
+		if (param->kind != AstNode_Field) {
+			continue;
+		}
+		ast_node(p, Field, param);
+		AstNode *type_expr = p->type;
+		Type *type = nullptr;
+		AstNode *default_value = unparen_expr(p->default_value);
+		ExactValue value = {};
+		bool default_is_nil = false;
+		bool default_is_location = false;
+		bool is_type_param = false;
+		bool is_type_polymorphic_type = false;
+		bool detemine_type_from_operand = false;
+		Type *specialization = nullptr;
+
+
+		if (type_expr == nullptr) {
+			if (default_value->kind == AstNode_BasicDirective &&
+			    default_value->BasicDirective.name == "caller_location") {
+				init_preload(c);
+				default_is_location = true;
+				type = t_source_code_location;
+			} else {
+				Operand o = {};
+				check_expr_or_type(c, &o, default_value);
+				if (is_operand_nil(o)) {
+					default_is_nil = true;
+				} else if (o.mode != Addressing_Constant) {
+					if (default_value->kind == AstNode_ProcLit) {
+						value = exact_value_procedure(default_value);
+					} else {
+						Entity *e = nullptr;
+						if (o.mode == Addressing_Value && is_type_proc(o.type)) {
+							Operand x = {};
+							if (default_value->kind == AstNode_Ident) {
+								e = check_ident(c, &x, default_value, nullptr, nullptr, false);
+							} else if (default_value->kind == AstNode_SelectorExpr) {
+								e = check_selector(c, &x, default_value, nullptr);
+							}
+						}
+
+						if (e != nullptr && e->kind == Entity_Procedure) {
+							value = exact_value_procedure(e->identifier);
+							add_entity_use(c, e->identifier, e);
+						} else {
+							error(default_value, "Default parameter must be a constant");
+						}
+					}
+				} else {
+					value = o.value;
+				}
+
+				type = default_type(o.type);
+			}
+		} else {
+			if (type_expr->kind == AstNode_Ellipsis) {
+				type_expr = type_expr->Ellipsis.expr;
+				if (i+1 == params.count) {
+					is_variadic = true;
+				} else {
+					error(param, "Invalid AST: Invalid variadic parameter");
+					success = false;
+				}
+			}
+			if (type_expr->kind == AstNode_TypeType) {
+				ast_node(tt, TypeType, type_expr);
+				is_type_param = true;
+				specialization = check_type(c, tt->specialization);
+				if (specialization == t_invalid){
+					specialization = nullptr;
+				}
+				// if (specialization) {
+				// 	if (!is_type_polymorphic(specialization)) {
+				// 		gbString str = type_to_string(specialization);
+				// 		error(tt->specialization, "Type specialization requires a polymorphic type, got %s", str);
+				// 		gb_string_free(str);
+				// 	}
+				// }
+
+				if (operands != nullptr) {
+					detemine_type_from_operand = true;
+					type = t_invalid;
+				} else {
+					type = make_type_generic(c->allocator, 0, str_lit(""), specialization);
+				}
+			} else {
+				bool prev = c->context.allow_polymorphic_types;
+				if (operands != nullptr) {
+					c->context.allow_polymorphic_types = true;
+				}
+				type = check_type(c, type_expr);
+
+				c->context.allow_polymorphic_types = prev;
+
+				if (is_type_polymorphic(type)) {
+					is_type_polymorphic_type = true;
+				}
+			}
+
+			if (default_value != nullptr) {
+				if (type_expr->kind == AstNode_TypeType) {
+					error(default_value, "A type parameter may not have a default value");
+				} else {
+					Operand o = {};
+					if (default_value->kind == AstNode_BasicDirective &&
+					    default_value->BasicDirective.name == "caller_location") {
+						init_preload(c);
+						default_is_location = true;
+						o.type = t_source_code_location;
+						o.mode = Addressing_Value;
+					} else {
+						check_expr_with_type_hint(c, &o, default_value, type);
+
+						if (is_operand_nil(o)) {
+							default_is_nil = true;
+						} else if (o.mode != Addressing_Constant) {
+							if (default_value->kind == AstNode_ProcLit) {
+								value = exact_value_procedure(default_value);
+							} else {
+								Entity *e = nullptr;
+								if (o.mode == Addressing_Value && is_type_proc(o.type)) {
+									Operand x = {};
+									if (default_value->kind == AstNode_Ident) {
+										e = check_ident(c, &x, default_value, nullptr, nullptr, false);
+									} else if (default_value->kind == AstNode_SelectorExpr) {
+										e = check_selector(c, &x, default_value, nullptr);
+									}
+								}
+
+								if (e != nullptr && e->kind == Entity_Procedure) {
+									value = exact_value_procedure(e->identifier);
+									add_entity_use(c, e->identifier, e);
+								} else {
+									error(default_value, "Default parameter must be a constant");
+								}
+							}
+						} else {
+							value = o.value;
+						}
+					}
+
+					check_is_assignable_to(c, &o, type);
+				}
+			}
+
+		}
+		if (type == nullptr) {
+			error(params[i], "Invalid parameter type");
+			type = t_invalid;
+		}
+		if (is_type_untyped(type)) {
+			if (is_type_untyped_undef(type)) {
+				error(params[i], "Cannot determine parameter type from ---");
+			} else {
+				error(params[i], "Cannot determine parameter type from a nil");
+			}
+			type = t_invalid;
+		}
+		if (is_type_empty_union(type)) {
+			gbString str = type_to_string(type);
+			error(params[i], "Invalid use of an empty union `%s`", str);
+			gb_string_free(str);
+			type = t_invalid;
+		}
+
+
+		if (p->flags&FieldFlag_c_vararg) {
+			if (p->type == nullptr ||
+			    p->type->kind != AstNode_Ellipsis) {
+				error(params[i], "`#c_vararg` can only be applied to variadic type fields");
+				p->flags &= ~FieldFlag_c_vararg; // Remove the flag
+			} else {
+				is_c_vararg = true;
+			}
+		}
+
+
+		for_array(j, p->names) {
+			AstNode *name = p->names[j];
+			if (!ast_node_expect(name, AstNode_Ident)) {
+				continue;
+			}
+
+			Entity *param = nullptr;
+			if (is_type_param) {
+				if (operands != nullptr) {
+					Operand o = (*operands)[variables.count];
+					if (o.mode == Addressing_Type) {
+						type = o.type;
+					} else {
+						if (!c->context.no_polymorphic_errors) {
+							error(o.expr, "Expected a type to assign to the type parameter");
+						}
+						success = false;
+						type = t_invalid;
+					}
+					if (is_type_polymorphic(type)) {
+						gbString str = type_to_string(type);
+						error(o.expr, "Cannot pass polymorphic type as a parameter, got `%s`", str);
+						gb_string_free(str);
+						success = false;
+						type = t_invalid;
+					}
+					bool modify_type = !c->context.no_polymorphic_errors;
+
+					if (specialization != nullptr && !check_type_specialization_to(c, specialization, type, false, modify_type)) {
+						if (!c->context.no_polymorphic_errors) {
+							gbString t = type_to_string(type);
+							gbString s = type_to_string(specialization);
+							error(o.expr, "Cannot convert type `%s` to the specialization `%s`", t, s);
+							gb_string_free(s);
+							gb_string_free(t);
+						}
+						success = false;
+						type = t_invalid;
+					}
+				}
+				param = make_entity_type_name(c->allocator, scope, name->Ident.token, type);
+				param->TypeName.is_type_alias = true;
+			} else {
+				if (operands != nullptr && is_type_polymorphic_type) {
+					Operand op = (*operands)[variables.count];
+					type = determine_type_from_polymorphic(c, type, op);
+					if (type == t_invalid) {
+						success = false;
+					} else if (!c->context.no_polymorphic_errors) {
+						// NOTE(bill): The type should be determined now and thus, no need to determine the type any more
+						is_type_polymorphic_type = false;
+						// is_type_polymorphic_type = is_type_polymorphic(base_type(type));
+					}
+				}
+
+				if (p->flags&FieldFlag_no_alias) {
+					if (!is_type_pointer(type)) {
+						error(params[i], "`#no_alias` can only be applied to fields of pointer type");
+						p->flags &= ~FieldFlag_no_alias; // Remove the flag
+					}
+				}
+
+				param = make_entity_param(c->allocator, scope, name->Ident.token, type,
+				                          (p->flags&FieldFlag_using) != 0, false);
+				param->Variable.default_value = value;
+				param->Variable.default_is_nil = default_is_nil;
+				param->Variable.default_is_location = default_is_location;
+
+			}
+			if (p->flags&FieldFlag_no_alias) {
+				param->flags |= EntityFlag_NoAlias;
+			}
+
+			add_entity(c, scope, name, param);
+			array_add(&variables, param);
+		}
+	}
+
+
+	if (is_variadic) {
+		GB_ASSERT(params.count > 0);
+		// NOTE(bill): Change last variadic parameter to be a slice
+		// Custom Calling convention for variadic parameters
+		Entity *end = variables[variable_count-1];
+		end->type = make_type_slice(c->allocator, end->type);
+		end->flags |= EntityFlag_Ellipsis;
+		if (is_c_vararg) {
+			end->flags |= EntityFlag_CVarArg;
+		}
+	}
+
+	isize specialization_count = 0;
+	if (scope != nullptr) {
+		for_array(i, scope->elements.entries) {
+			Entity *e = scope->elements.entries[i].value;
+			if (e->kind == Entity_TypeName) {
+				Type *t = e->type;
+				if (t->kind == Type_Generic &&
+				    t->Generic.specialized != nullptr) {
+					specialization_count += 1;
+				}
+			}
+		}
+	}
+
+	Type *tuple = make_type_tuple(c->allocator);
+	tuple->Tuple.variables = variables;
+
+	if (success_) *success_ = success;
+	if (specialization_count_) *specialization_count_ = specialization_count;
+	if (is_variadic_) *is_variadic_ = is_variadic;
+
+	return tuple;
+}
+
+Type *check_get_results(Checker *c, Scope *scope, AstNode *_results) {
+	if (_results == nullptr) {
+		return nullptr;
+	}
+	ast_node(field_list, FieldList, _results);
+	Array<AstNode *> results = field_list->list;
+
+	if (results.count == 0) {
+		return nullptr;
+	}
+	Type *tuple = make_type_tuple(c->allocator);
+
+	isize variable_count = 0;
+	for_array(i, results) {
+		AstNode *field = results[i];
+		if (ast_node_expect(field, AstNode_Field)) {
+			ast_node(f, Field, field);
+			variable_count += gb_max(f->names.count, 1);
+		}
+	}
+
+	Array<Entity *> variables = {};
+	array_init(&variables, c->allocator, variable_count);
+	for_array(i, results) {
+		ast_node(field, Field, results[i]);
+		AstNode *default_value = unparen_expr(field->default_value);
+		ExactValue value = {};
+		bool default_is_nil = false;
+
+		Type *type = nullptr;
+		if (field->type == nullptr) {
+			Operand o = {};
+			check_expr(c, &o, default_value);
+			if (is_operand_nil(o)) {
+				default_is_nil = true;
+			} else if (o.mode != Addressing_Constant) {
+				error(default_value, "Default parameter must be a constant");
+			} else {
+				value = o.value;
+			}
+
+			type = default_type(o.type);
+		} else {
+			type = check_type(c, field->type);
+
+			if (default_value != nullptr) {
+				Operand o = {};
+				check_expr_with_type_hint(c, &o, default_value, type);
+
+				if (is_operand_nil(o)) {
+					default_is_nil = true;
+				} else if (o.mode != Addressing_Constant) {
+					error(default_value, "Default parameter must be a constant");
+				} else {
+					value = o.value;
+				}
+				check_is_assignable_to(c, &o, type);
+			}
+		}
+
+		if (type == nullptr) {
+			error(results[i], "Invalid parameter type");
+			type = t_invalid;
+		}
+		if (is_type_untyped(type)) {
+			error(results[i], "Cannot determine parameter type from a nil");
+			type = t_invalid;
+		}
+
+
+		if (field->names.count == 0) {
+			Token token = ast_node_token(field->type);
+			token.string = str_lit("");
+			Entity *param = make_entity_param(c->allocator, scope, token, type, false, false);
+			param->Variable.default_value = value;
+			param->Variable.default_is_nil = default_is_nil;
+			array_add(&variables, param);
+		} else {
+			for_array(j, field->names) {
+				Token token = ast_node_token(results[i]);
+				if (field->type != nullptr) {
+					token = ast_node_token(field->type);
+				}
+				token.string = str_lit("");
+
+				AstNode *name = field->names[j];
+				if (name->kind != AstNode_Ident) {
+					error(name, "Expected an identifer for as the field name");
+				} else {
+					token = name->Ident.token;
+				}
+
+				Entity *param = make_entity_param(c->allocator, scope, token, type, false, false);
+				param->Variable.default_value = value;
+				param->Variable.default_is_nil = default_is_nil;
+				array_add(&variables, param);
+			}
+		}
+	}
+
+	for_array(i, variables) {
+		String x = variables[i]->token.string;
+		if (x.len == 0 || is_blank_ident(x)) {
+			continue;
+		}
+		for (isize j = i+1; j < variables.count; j++) {
+			String y = variables[j]->token.string;
+			if (y.len == 0 || is_blank_ident(y)) {
+				continue;
+			}
+			if (x == y) {
+				error(variables[j]->token, "Duplicate return value name `%.*s`", LIT(y));
+			}
+		}
+	}
+
+	tuple->Tuple.variables = variables;
+
+	return tuple;
+}
+
+Type *type_to_abi_compat_param_type(gbAllocator a, Type *original_type) {
+	Type *new_type = original_type;
+
+	if (build_context.ODIN_ARCH == "x86") {
+		return new_type;
+	}
+
+	if (build_context.ODIN_OS == "windows") {
+		// NOTE(bill): Changing the passing parameter value type is to match C's ABI
+		// IMPORTANT TODO(bill): This only matches the ABI on MSVC at the moment
+		// SEE: https://msdn.microsoft.com/en-us/library/zthk2dkh.aspx
+		Type *bt = core_type(original_type);
+		switch (bt->kind) {
+		// Okay to pass by value (usually)
+		// Especially the only Odin types
+		case Type_Basic: {
+			i64 sz = bt->Basic.size;
+			if (sz > 8 && build_context.word_size < 8) {
+				new_type = make_type_pointer(a, original_type);
+			}
+			break;
+		}
+		case Type_Pointer: break;
+		case Type_Proc:    break; // NOTE(bill): Just a pointer
+
+		// Odin only types
+		case Type_Slice:
+		case Type_DynamicArray:
+		case Type_Map:
+			break;
+
+		// Odin specific
+		case Type_Array:
+		case Type_Vector:
+		// Could be in C too
+		case Type_Struct: {
+			i64 align = type_align_of(a, original_type);
+			i64 size  = type_size_of(a, original_type);
+			switch (8*size) {
+			case 8:  new_type = t_u8;  break;
+			case 16: new_type = t_u16; break;
+			case 32: new_type = t_u32; break;
+			case 64: new_type = t_u64; break;
+			default:
+				new_type = make_type_pointer(a, original_type);
+				break;
+			}
+
+			break;
+		}
+		}
+	} else if (build_context.ODIN_OS == "linux" ||
+	           build_context.ODIN_OS == "osx") {
+		Type *bt = core_type(original_type);
+		switch (bt->kind) {
+		// Okay to pass by value (usually)
+		// Especially the only Odin types
+		case Type_Basic: {
+			i64 sz = bt->Basic.size;
+			if (sz > 8 && build_context.word_size < 8) {
+				new_type = make_type_pointer(a, original_type);
+			}
+
+			break;
+		}
+		case Type_Pointer: break;
+		case Type_Proc:    break; // NOTE(bill): Just a pointer
+
+		// Odin only types
+		case Type_Slice:
+		case Type_DynamicArray:
+		case Type_Map:
+			break;
+
+		// Odin specific
+		case Type_Array:
+		case Type_Vector:
+		// Could be in C too
+		case Type_Struct: {
+			i64 align = type_align_of(a, original_type);
+			i64 size  = type_size_of(a, original_type);
+			if (8*size > 16) {
+				new_type = make_type_pointer(a, original_type);
+			}
+
+			break;
+		}
+		}
+	} else {
+		// IMPORTANT TODO(bill): figure out the ABI settings for Linux, OSX etc. for
+		// their architectures
+	}
+
+	return new_type;
+}
+
+Type *reduce_tuple_to_single_type(Type *original_type) {
+	if (original_type != nullptr) {
+		Type *t = core_type(original_type);
+		if (t->kind == Type_Tuple && t->Tuple.variables.count == 1) {
+			return t->Tuple.variables[0]->type;
+		}
+	}
+	return original_type;
+}
+
+Type *type_to_abi_compat_result_type(gbAllocator a, Type *original_type) {
+	Type *new_type = original_type;
+	if (new_type == nullptr) {
+		return nullptr;
+	}
+	GB_ASSERT(is_type_tuple(original_type));
+
+
+
+	if (build_context.ODIN_OS == "windows") {
+		Type *bt = core_type(reduce_tuple_to_single_type(original_type));
+		// NOTE(bill): This is just reversed engineered from LLVM IR output
+		switch (bt->kind) {
+		// Okay to pass by value
+		// Especially the only Odin types
+		case Type_Pointer: break;
+		case Type_Proc:    break; // NOTE(bill): Just a pointer
+		case Type_Basic:   break;
+
+
+		default: {
+			i64 align = type_align_of(a, original_type);
+			i64 size  = type_size_of(a, original_type);
+			switch (8*size) {
+#if 1
+			case 8:  new_type = t_u8;  break;
+			case 16: new_type = t_u16; break;
+			case 32: new_type = t_u32; break;
+			case 64: new_type = t_u64; break;
+#endif
+			}
+
+			break;
+		}
+		}
+	} else if (build_context.ODIN_OS == "linux") {
+
+	} else {
+		// IMPORTANT TODO(bill): figure out the ABI settings for Linux, OSX etc. for
+		// their architectures
+	}
+
+	if (new_type != original_type) {
+		Type *tuple = make_type_tuple(a);
+		Array<Entity *> variables = {};
+		array_init(&variables, a, 1);
+		array_add(&variables, make_entity_param(a, original_type->Tuple.variables[0]->scope, empty_token, new_type, false, false));
+		tuple->Tuple.variables = variables;
+		new_type = tuple;
+	}
+
+
+	// return reduce_tuple_to_single_type(new_type);
+	return new_type;
+}
+
+bool abi_compat_return_by_value(gbAllocator a, ProcCallingConvention cc, Type *abi_return_type) {
+	if (abi_return_type == nullptr) {
+		return false;
+	}
+	switch (cc) {
+	case ProcCC_Odin:
+	case ProcCC_Contextless:
+		return false;
+	}
+
+
+	if (build_context.ODIN_OS == "windows") {
+		i64 size = 8*type_size_of(a, abi_return_type);
+		switch (size) {
+		case 0:
+		case 8:
+		case 16:
+		case 32:
+		case 64:
+			return false;
+		default:
+			return true;
+		}
+	}
+	return false;
+}
+
+// NOTE(bill): `operands` is for generating non generic procedure type
+bool check_procedure_type(Checker *c, Type *type, AstNode *proc_type_node, Array<Operand> *operands) {
+	ast_node(pt, ProcType, proc_type_node);
+
+	if (c->context.polymorphic_scope == nullptr && c->context.allow_polymorphic_types) {
+		c->context.polymorphic_scope = c->context.scope;
+	}
+
+	bool variadic = false;
+	bool success = true;
+	isize specialization_count = 0;
+	Type *params  = check_get_params(c, c->context.scope, pt->params, &variadic, &success, &specialization_count, operands);
+	Type *results = check_get_results(c, c->context.scope, pt->results);
+
+
+	isize param_count = 0;
+	isize result_count = 0;
+	if (params)  param_count  = params ->Tuple.variables.count;
+	if (results) result_count = results->Tuple.variables.count;
+
+	if (param_count > 0) {
+		for_array(i, params->Tuple.variables) {
+			Entity *param = params->Tuple.variables[i];
+			if (param->kind == Entity_Variable && param->Variable.default_value.kind == ExactValue_Procedure) {
+				type->Proc.has_proc_default_values = true;
+				break;
+			}
+		}
+	}
+
+	type->Proc.node                 = proc_type_node;
+	type->Proc.scope                = c->context.scope;
+	type->Proc.params               = params;
+	type->Proc.param_count          = cast(i32)param_count;
+	type->Proc.results              = results;
+	type->Proc.result_count         = cast(i32)result_count;
+	type->Proc.variadic             = variadic;
+	type->Proc.calling_convention   = pt->calling_convention;
+	type->Proc.is_polymorphic       = pt->generic;
+	type->Proc.specialization_count = specialization_count;
+
+	if (param_count > 0) {
+		Entity *end = params->Tuple.variables[param_count-1];
+		if (end->flags&EntityFlag_CVarArg) {
+			if (pt->calling_convention == ProcCC_Odin) {
+				error(end->token, "Odin calling convention does not support #c_vararg");
+			} else if (pt->calling_convention == ProcCC_Contextless) {
+				error(end->token, "Odin's contextless calling convention does not support #c_vararg");
+			} else if (pt->calling_convention == ProcCC_Fast) {
+				error(end->token, "Fast calling convention does not support #c_vararg");
+			} else {
+				type->Proc.c_vararg = true;
+			}
+		}
+	}
+
+
+	bool is_polymorphic = false;
+	for (isize i = 0; i < param_count; i++) {
+		Entity *e = params->Tuple.variables[i];
+		if (e->kind != Entity_Variable) {
+			is_polymorphic = true;
+			break;
+		} else if (is_type_polymorphic(e->type)) {
+			is_polymorphic = true;
+			break;
+		}
+	}
+	type->Proc.is_polymorphic = is_polymorphic;
+
+
+	type->Proc.abi_compat_params = gb_alloc_array(c->allocator, Type *, param_count);
+	for (isize i = 0; i < param_count; i++) {
+		Entity *e = type->Proc.params->Tuple.variables[i];
+		if (e->kind == Entity_Variable) {
+			Type *original_type = e->type;
+			Type *new_type = type_to_abi_compat_param_type(c->allocator, original_type);
+			type->Proc.abi_compat_params[i] = new_type;
+		}
+	}
+
+	// NOTE(bill): The types are the same
+	type->Proc.abi_compat_result_type = type_to_abi_compat_result_type(c->allocator, type->Proc.results);
+	type->Proc.return_by_pointer = abi_compat_return_by_value(c->allocator, pt->calling_convention, type->Proc.abi_compat_result_type);
+
+	return success;
+}
+
+
+i64 check_array_count(Checker *c, AstNode *e) {
+	if (e == nullptr) {
+		return 0;
+	}
+	Operand o = {};
+	if (e->kind == AstNode_UnaryExpr &&
+	    e->UnaryExpr.op.kind == Token_Ellipsis) {
+		return -1;
+	}
+
+	check_expr(c, &o, e);
+	if (o.mode != Addressing_Constant) {
+		if (o.mode != Addressing_Invalid) {
+			error(e, "Array count must be a constant");
+		}
+		return 0;
+	}
+	Type *type = base_type(o.type);
+	if (is_type_untyped(type) || is_type_integer(type)) {
+		if (o.value.kind == ExactValue_Integer) {
+			i64 count = i128_to_i64(o.value.value_integer);
+			if (count >= 0) {
+				return count;
+			}
+			error(e, "Invalid negative array count %lld", cast(long long)count);
+			return 0;
+		}
+	}
+
+	error(e, "Array count must be an integer");
+	return 0;
+}
+
+Type *make_optional_ok_type(gbAllocator a, Type *value) {
+	bool typed = true;
+	Type *t = make_type_tuple(a);
+	array_init(&t->Tuple.variables, a, 2);
+	array_add (&t->Tuple.variables, make_entity_field(a, nullptr, blank_token, value,  false, 0));
+	array_add (&t->Tuple.variables, make_entity_field(a, nullptr, blank_token, typed ? t_bool : t_untyped_bool, false, 1));
+	return t;
+}
+
+void generate_map_entry_type(gbAllocator a, Type *type) {
+	GB_ASSERT(type->kind == Type_Map);
+	if (type->Map.entry_type != nullptr) return;
+
+	// NOTE(bill): The preload types may have not been set yet
+	GB_ASSERT(t_map_key != nullptr);
+
+	Type *entry_type = make_type_struct(a);
+
+	/*
+	struct {
+		hash:  __MapKey;
+		next:  int;
+		key:   Key;
+		value: Value;
+	}
+	*/
+	AstNode *dummy_node = gb_alloc_item(a, AstNode);
+	dummy_node->kind = AstNode_Invalid;
+	Scope *s = create_scope(universal_scope, a);
+
+	isize field_count = 3;
+	Array<Entity *> fields = {};
+	array_init(&fields, a, 3);
+	array_add(&fields, make_entity_field(a, s, make_token_ident(str_lit("key")),   t_map_key,       false, 0));
+	array_add(&fields, make_entity_field(a, s, make_token_ident(str_lit("next")),  t_int,           false, 1));
+	array_add(&fields, make_entity_field(a, s, make_token_ident(str_lit("value")), type->Map.value, false, 2));
+
+
+	entry_type->Struct.is_ordered          = true;
+	entry_type->Struct.fields              = fields;
+	entry_type->Struct.fields_in_src_order = fields;
+
+	// type_set_offsets(a, entry_type);
+	type->Map.entry_type = entry_type;
+}
+
+void generate_map_internal_types(gbAllocator a, Type *type) {
+	GB_ASSERT(type->kind == Type_Map);
+	generate_map_entry_type(a, type);
+	if (type->Map.generated_struct_type != nullptr) return;
+	Type *key   = type->Map.key;
+	Type *value = type->Map.value;
+	GB_ASSERT(key != nullptr);
+	GB_ASSERT(value != nullptr);
+
+	Type *generated_struct_type = make_type_struct(a);
+
+	/*
+	struct {
+		hashes:  [dynamic]int;
+		entries: [dynamic]EntryType;
+	}
+	*/
+	AstNode *dummy_node = gb_alloc_item(a, AstNode);
+	dummy_node->kind = AstNode_Invalid;
+	Scope *s = create_scope(universal_scope, a);
+
+	Type *hashes_type  = make_type_dynamic_array(a, t_int);
+	Type *entries_type = make_type_dynamic_array(a, type->Map.entry_type);
+
+
+	Array<Entity *> fields = {};
+	array_init(&fields, a, 2);
+	array_add(&fields, make_entity_field(a, s, make_token_ident(str_lit("hashes")),  hashes_type,  false, 0));
+	array_add(&fields, make_entity_field(a, s, make_token_ident(str_lit("entries")), entries_type, false, 1));
+
+	generated_struct_type->Struct.is_ordered          = true;
+	generated_struct_type->Struct.fields              = fields;
+	generated_struct_type->Struct.fields_in_src_order = fields;
+
+	type_set_offsets(a, generated_struct_type);
+	type->Map.generated_struct_type = generated_struct_type;
+	type->Map.lookup_result_type = make_optional_ok_type(a, value);
+}
+
+void check_map_type(Checker *c, Type *type, AstNode *node) {
+	GB_ASSERT(type->kind == Type_Map);
+	ast_node(mt, MapType, node);
+
+	Type *key   = check_type(c, mt->key);
+	Type *value = check_type(c, mt->value);
+
+	if (!is_type_valid_for_keys(key)) {
+		if (is_type_boolean(key)) {
+			error(node, "A boolean cannot be used as a key for a map, use an array instead for this case");
+		} else {
+			gbString str = type_to_string(key);
+			error(node, "Invalid type of a key for a map, got `%s`", str);
+			gb_string_free(str);
+		}
+	}
+
+	type->Map.key   = key;
+	type->Map.value = value;
+
+
+	init_preload(c);
+	generate_map_internal_types(c->allocator, type);
+
+	// error(node, "`map` types are not yet implemented");
+}
+
+bool check_type_internal(Checker *c, AstNode *e, Type **type, Type *named_type) {
+	GB_ASSERT_NOT_NULL(type);
+	if (e == nullptr) {
+		*type = t_invalid;
+		return true;
+	}
+
+	switch (e->kind) {
+	case_ast_node(i, Ident, e);
+
+		Operand o = {};
+		check_ident(c, &o, e, named_type, nullptr, false);
+
+		gbString err_str;
+		switch (o.mode) {
+		case Addressing_Invalid:
+			break;
+		case Addressing_Type:
+			*type = o.type;
+			return true;
+
+		case Addressing_NoValue:
+			err_str = expr_to_string(e);
+			error(e, "`%s` used as a type", err_str);
+			gb_string_free(err_str);
+			break;
+
+		default:
+			err_str = expr_to_string(e);
+			error(e, "`%s` used as a type when not a type", err_str);
+			gb_string_free(err_str);
+			break;
+		}
+	case_end;
+
+	case_ast_node(ht, HelperType, e);
+		return check_type_internal(c, ht->type, type, named_type);
+	case_end;
+
+	case_ast_node(pt, PolyType, e);
+		AstNode *ident = pt->type;
+		if (ident->kind != AstNode_Ident) {
+			error(ident, "Expected an identifier after the $");
+			*type = t_invalid;
+			return false;
+		}
+
+		Token token = ident->Ident.token;
+		Type *specific = nullptr;
+		if (pt->specialization != nullptr) {
+			AstNode *s = pt->specialization;
+			specific = check_type(c, s);
+			if (false && !is_type_polymorphic_struct(specific)) {
+				gbString str = type_to_string(specific);
+				error(s, "Expected a polymorphic struct, got %s", str);
+				gb_string_free(str);
+				specific = nullptr;
+			}
+		}
+		Type *t = make_type_generic(c->allocator, 0, token.string, specific);
+		if (c->context.allow_polymorphic_types) {
+			Scope *ps = c->context.polymorphic_scope;
+			Scope *s = c->context.scope;
+			Scope *entity_scope = s;
+			if (ps != nullptr && ps != s) {
+				GB_ASSERT(is_scope_an_ancestor(ps, s) >= 0);
+				entity_scope = ps;
+			}
+			Entity *e = make_entity_type_name(c->allocator, entity_scope, token, t);
+			e->TypeName.is_type_alias = true;
+			add_entity(c, ps, ident, e);
+			add_entity(c, s, ident, e);
+		} else {
+			error(ident, "Invalid use of a polymorphic type `$%.*s`", LIT(token.string));
+			*type = t_invalid;
+			return false;
+		}
+		*type = t;
+		return true;
+	case_end;
+
+	case_ast_node(se, SelectorExpr, e);
+		Operand o = {};
+		check_selector(c, &o, e, nullptr);
+
+		gbString err_str;
+		switch (o.mode) {
+		case Addressing_Invalid:
+			break;
+		case Addressing_Type:
+			GB_ASSERT(o.type != nullptr);
+			*type = o.type;
+			return true;
+		case Addressing_NoValue:
+			err_str = expr_to_string(e);
+			error(e, "`%s` used as a type", err_str);
+			gb_string_free(err_str);
+			break;
+		default:
+			err_str = expr_to_string(e);
+			error(e, "`%s` is not a type", err_str);
+			gb_string_free(err_str);
+			break;
+		}
+	case_end;
+
+	case_ast_node(pe, ParenExpr, e);
+		*type = check_type(c, pe->expr, named_type);
+		return true;
+	case_end;
+
+	case_ast_node(ue, UnaryExpr, e);
+		if (ue->op.kind == Token_Pointer) {
+			*type = make_type_pointer(c->allocator, check_type(c, ue->expr));
+			return true;
+		} /* else if (ue->op.kind == Token_Maybe) {
+			*type = make_type_maybe(c->allocator, check_type(c, ue->expr));
+			return true;
+		} */
+	case_end;
+
+	case_ast_node(pt, PointerType, e);
+		Type *elem = check_type(c, pt->type);
+		i64 esz = type_size_of(c->allocator, elem);
+		*type = make_type_pointer(c->allocator, elem);
+		return true;
+	case_end;
+
+	case_ast_node(at, ArrayType, e);
+		if (at->count != nullptr) {
+			Type *elem = check_type(c, at->elem, nullptr);
+			i64 count = check_array_count(c, at->count);
+			if (count < 0) {
+				error(at->count, "... can only be used in conjuction with compound literals");
+				count = 0;
+			}
+			*type = make_type_array(c->allocator, elem, count);
+		} else {
+			Type *elem = check_type(c, at->elem);
+			*type = make_type_slice(c->allocator, elem);
+		}
+		return true;
+	case_end;
+
+	case_ast_node(dat, DynamicArrayType, e);
+		Type *elem = check_type(c, dat->elem);
+		*type = make_type_dynamic_array(c->allocator, elem);
+		return true;
+	case_end;
+
+
+
+	case_ast_node(vt, VectorType, e);
+		Type *elem = check_type(c, vt->elem);
+		Type *be = base_type(elem);
+		i64 count = check_array_count(c, vt->count);
+		if (is_type_vector(be) || (!is_type_boolean(be) && !is_type_numeric(be) && be->kind != Type_Generic)) {
+			gbString err_str = type_to_string(elem);
+			error(vt->elem, "Vector element type must be numerical or a boolean, got `%s`", err_str);
+			gb_string_free(err_str);
+		}
+		*type = make_type_vector(c->allocator, elem, count);
+		return true;
+	case_end;
+
+	case_ast_node(st, StructType, e);
+		*type = make_type_struct(c->allocator);
+		set_base_type(named_type, *type);
+		check_open_scope(c, e);
+		check_struct_type(c, *type, e, nullptr, named_type);
+		check_close_scope(c);
+		(*type)->Struct.node = e;
+		return true;
+	case_end;
+
+	case_ast_node(ut, UnionType, e);
+		*type = make_type_union(c->allocator);
+		set_base_type(named_type, *type);
+		check_open_scope(c, e);
+		check_union_type(c, *type, e);
+		check_close_scope(c);
+		(*type)->Union.node = e;
+		return true;
+	case_end;
+
+	case_ast_node(et, EnumType, e);
+		*type = make_type_enum(c->allocator);
+		set_base_type(named_type, *type);
+		check_open_scope(c, e);
+		check_enum_type(c, *type, named_type, e);
+		check_close_scope(c);
+		(*type)->Enum.node = e;
+		return true;
+	case_end;
+
+	case_ast_node(et, BitFieldType, e);
+		*type = make_type_bit_field(c->allocator);
+		set_base_type(named_type, *type);
+		check_open_scope(c, e);
+		check_bit_field_type(c, *type, e);
+		check_close_scope(c);
+		return true;
+	case_end;
+
+	case_ast_node(pt, ProcType, e);
+		*type = alloc_type(c->allocator, Type_Proc);
+		set_base_type(named_type, *type);
+		check_open_scope(c, e);
+		check_procedure_type(c, *type, e);
+		check_close_scope(c);
+		return true;
+	case_end;
+
+	case_ast_node(mt, MapType, e);
+		*type = alloc_type(c->allocator, Type_Map);
+		set_base_type(named_type, *type);
+		check_map_type(c, *type, e);
+		return true;
+	case_end;
+
+	case_ast_node(ce, CallExpr, e);
+		Operand o = {};
+		check_expr_or_type(c, &o, e);
+		if (o.mode == Addressing_Type) {
+			*type = o.type;
+			return true;
+		}
+	case_end;
+
+	case_ast_node(te, TernaryExpr, e);
+		Operand o = {};
+		check_expr_or_type(c, &o, e);
+		if (o.mode == Addressing_Type) {
+			*type = o.type;
+			return true;
+		}
+	case_end;
+	}
+
+	*type = t_invalid;
+	return false;
+}
+
+
+
+Type *check_type(Checker *c, AstNode *e, Type *named_type) {
+	Type *type = nullptr;
+	bool ok = check_type_internal(c, e, &type, named_type);
+
+	if (!ok) {
+		gbString err_str = expr_to_string(e);
+		error(e, "`%s` is not a type", err_str);
+		gb_string_free(err_str);
+		type = t_invalid;
+	}
+
+	if (type == nullptr) {
+		type = t_invalid;
+	}
+
+	if (type->kind == Type_Named &&
+	    type->Named.base == nullptr) {
+		// IMPORTANT TODO(bill): Is this a serious error?!
+		#if 0
+		error(e, "Invalid type definition of `%.*s`", LIT(type->Named.name));
+		#endif
+		type->Named.base = t_invalid;
+	}
+
+	#if 0
+	if (!c->context.allow_polymorphic_types && is_type_polymorphic(type)) {
+		gbString str = type_to_string(type);
+		error(e, "Invalid use of a polymorphic type `%s`", str);
+		gb_string_free(str);
+		type = t_invalid;
+	}
+	#endif
+
+	if (is_type_typed(type)) {
+		add_type_and_value(&c->info, e, Addressing_Type, type, empty_exact_value);
+	} else {
+		gbString name = type_to_string(type);
+		error(e, "Invalid type definition of %s", name);
+		gb_string_free(name);
+		type = t_invalid;
+	}
+	set_base_type(named_type, type);
+
+	return type;
+}