Allow using on bit fields

2 files changed, 18 insertions, 7 deletions

diff --git a/src/check_expr.c b/src/check_expr.c
index d5a26a193..866a5f1a4 100644
--- a/src/check_expr.c
+++ b/src/check_expr.c
@@ -452,7 +452,7 @@ isize check_fields(Checker *c, AstNode *node, AstNodeArray decls,
 
 		if (is_using) {
 			Type *t = base_type(type_deref(type));
-			if (!is_type_struct(t) && !is_type_raw_union(t) &&
+			if (!is_type_struct(t) && !is_type_raw_union(t) && !is_type_bit_field(t) &&
 			    f->names.count >= 1 &&
 			    f->names.e[0]->kind == AstNode_Ident) {
 				Token name_token = f->names.e[0]->Ident;
@@ -477,7 +477,9 @@ isize check_fields(Checker *c, AstNode *node, AstNodeArray decls,
 						error(name_token, "Previous `using` for an index expression `%.*s`", LIT(name_token.string));
 					}
 				} else {
-					error(name_token, "`using` on a field `%.*s` must be a `struct` or `raw_union`", LIT(name_token.string));
+					gbString type_str = type_to_string(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;
 				}
 			}
@@ -2258,7 +2260,8 @@ void check_unary_expr(Checker *c, Operand *o, Token op, AstNode *node) {
 
 		if (o->mode != Addressing_Variable ||
 		    check_is_expr_vector_index(c, o->expr) ||
-		    check_is_vector_elem(c, o->expr)) {
+		    check_is_vector_elem(c, o->expr) ||
+		    is_type_bit_field_value(o->type)) {
 			if (ast_node_expect(node, AstNode_UnaryExpr)) {
 				ast_node(ue, UnaryExpr, node);
 				gbString str = expr_to_string(ue->expr);
diff --git a/src/ir.c b/src/ir.c
index 2002c7a4c..f2b75b88d 100644
--- a/src/ir.c
+++ b/src/ir.c
@@ -4836,10 +4836,18 @@ irAddr ir_build_addr(irProcedure *proc, AstNode *expr) {
 			if (sel.entity->type->kind == Type_BitFieldValue) {
 				irAddr addr = ir_build_addr(proc, se->expr);
 				Type *bft = type_deref(ir_addr_type(addr));
-				GB_ASSERT(is_type_bit_field(bft));
-				GB_ASSERT(sel.index.count == 1);
-				i32 index = sel.index.e[0];
-				return ir_addr_bit_field(addr.addr, index);
+				if (sel.index.count == 1) {
+					GB_ASSERT(is_type_bit_field(bft));
+					i32 index = sel.index.e[0];
+					return ir_addr_bit_field(addr.addr, index);
+				} else {
+					Selection s = sel;
+					s.index.count--;
+					i32 index = s.index.e[s.index.count-1];
+					irValue *a = addr.addr;
+					a = ir_emit_deep_field_gep(proc, a, s);
+					return ir_addr_bit_field(a, index);
+				}
 			} else {
 				irValue *a = ir_build_addr(proc, se->expr).addr;
 				a = ir_emit_deep_field_gep(proc, a, sel);