Add `intrinsics.type_struct_has_implicit_padding` #3844

1 files changed, 25 insertions, 0 deletions

diff --git a/src/check_builtin.cpp b/src/check_builtin.cpp
index c1422e80e..7a1a8b9ee 100644
--- a/src/check_builtin.cpp
+++ b/src/check_builtin.cpp
@@ -5839,6 +5839,31 @@ gb_internal bool check_builtin_procedure(CheckerContext *c, Operand *operand, As
 		operand->mode = Addressing_Constant;
 		operand->type = t_untyped_integer;
 		break;
+	case BuiltinProc_type_struct_has_implicit_padding:
+		operand->value = exact_value_bool(false);
+		if (operand->mode != Addressing_Type) {
+			error(operand->expr, "Expected a struct type for '%.*s'", LIT(builtin_name));
+		} else if (!is_type_struct(operand->type) && !is_type_soa_struct(operand->type)) {
+			error(operand->expr, "Expected a struct type for '%.*s'", LIT(builtin_name));
+		} else {
+			Type *bt = base_type(operand->type);
+			if (bt->Struct.is_packed) {
+				operand->value = exact_value_bool(false);
+			} else if (bt->Struct.fields.count != 0) {
+				i64 size = type_size_of(bt);
+				Type *field_type = nullptr;
+				i64 last_offset = type_offset_of(bt, bt->Struct.fields.count-1, &field_type);
+				if (last_offset+type_size_of(field_type) < size) {
+					operand->value = exact_value_bool(true);
+				} else {
+					i64 packed_size = type_size_of_struct_pretend_is_packed(bt);
+					operand->value = exact_value_bool(packed_size < size);
+				}
+			}
+		}
+		operand->mode = Addressing_Constant;
+		operand->type = t_untyped_bool;
+		break;
 
 	case BuiltinProc_type_proc_parameter_count:
 		operand->value = exact_value_i64(0);