Support using of a bit_field within a struct

src/check_type.cpp

@@ -89,6 +89,8 @@ gb_internal bool does_field_type_allow_using(Type *t) {
 		return true;
 	} else if (is_type_array(t)) {
 		return t->Array.count <= 4;
+	} else if (is_type_bit_field(t)) {
+		return true;
 	}
 	return false;
 }

src/llvm_backend_expr.cpp

@@ -4679,12 +4679,20 @@ gb_internal lbAddr lb_build_addr_internal(lbProcedure *p, Ast *expr) {
 			GB_ASSERT(sel.entity != nullptr);
 			if (sel.is_bit_field) {
 				lbAddr addr = lb_build_addr(p, se->expr);
-				Type *bf_type = base_type(type_deref(lb_addr_type(addr)));
+
+
+				Selection sub_sel = sel;
+				sub_sel.index.count -= 1;
+
+				Type *bf_type = type_from_selection(type, sub_sel);
+				bf_type = base_type(type_deref(bf_type));
 				GB_ASSERT(bf_type->kind == Type_BitField);
 
 				lbValue a = lb_addr_get_ptr(p, addr);
-				Selection sub_sel = sel;
+				if (sub_sel.index.count > 0) {
-				sub_sel.index.count -= 1;
+					a = lb_emit_deep_field_gep(p, a, sub_sel);
+				}
+
 				i32 index = sel.index[sel.index.count-1];
 
 				Entity *f = bf_type->BitField.fields[index];

src/llvm_backend_utility.cpp

@@ -1332,7 +1332,7 @@ gb_internal lbValue lb_emit_deep_field_gep(lbProcedure *p, lbValue e, Selection
 				if (index == 0) {
 					type = t_rawptr;
 				} else if (index == 1) {
-					type = t_type_info_ptr;
+					type = t_typeid;
 				}
 				e = lb_emit_struct_ep(p, e, index);
 				break;

src/types.cpp

@@ -385,6 +385,9 @@ enum : int {
 
 gb_internal bool is_type_comparable(Type *t);
 gb_internal bool is_type_simple_compare(Type *t);
+gb_internal Type *type_deref(Type *t, bool allow_multi_pointer=false);
+gb_internal Type *base_type(Type *t);
+gb_internal Type *alloc_type_multi_pointer(Type *elem);
 
 gb_internal u32 type_info_flags_of_type(Type *type) {
 	if (type == nullptr) {
@@ -762,7 +765,6 @@ gb_internal bool  is_type_proc(Type *t);
 gb_internal bool  is_type_slice(Type *t);
 gb_internal bool  is_type_integer(Type *t);
 gb_internal bool  type_set_offsets(Type *t);
-gb_internal Type *base_type(Type *t);
 
 gb_internal i64 type_size_of_internal(Type *t, TypePath *path);
 gb_internal i64 type_align_of_internal(Type *t, TypePath *path);
@@ -1157,7 +1159,7 @@ gb_internal Type *alloc_type_simd_vector(i64 count, Type *elem, Type *generic_co
 ////////////////////////////////////////////////////////////////
 
 
-gb_internal Type *type_deref(Type *t, bool allow_multi_pointer=false) {
+gb_internal Type *type_deref(Type *t, bool allow_multi_pointer) {
 	if (t != nullptr) {
 		Type *bt = base_type(t);
 		if (bt == nullptr) {
@@ -4261,6 +4263,71 @@ gb_internal Type *alloc_type_proc_from_types(Type **param_types, unsigned param_
 }
 
 
+gb_internal Type *type_from_selection(Type *type, Selection const &sel) {
+	for (i32 index : sel.index) {
+		Type *bt = base_type(type_deref(type));
+		switch (bt->kind) {
+		case Type_Struct:
+			type = bt->Struct.fields[index]->type;
+			break;
+		case Type_Tuple:
+			type = bt->Tuple.variables[index]->type;
+			break;
+		case Type_BitField:
+			type = bt->BitField.fields[index]->type;
+			break;
+		case Type_Array:
+			type = bt->Array.elem;
+			break;
+		case Type_EnumeratedArray:
+			type = bt->Array.elem;
+			break;
+		case Type_Slice:
+			switch (index) {
+			case 0: type = alloc_type_multi_pointer(bt->Slice.elem); break;
+			case 1: type = t_int;                                    break;
+			}
+			break;
+		case Type_DynamicArray:
+			switch (index) {
+			case 0: type = alloc_type_multi_pointer(bt->DynamicArray.elem); break;
+			case 1: type = t_int;                                           break;
+			case 2: type = t_int;                                           break;
+			case 3: type = t_allocator;                                     break;
+			}
+			break;
+		case Type_Map:
+			switch (index) {
+			case 0: type = t_uintptr;   break;
+			case 1: type = t_int;       break;
+			case 2: type = t_allocator; break;
+			}
+			break;
+		case Type_Basic:
+			if (is_type_complex_or_quaternion(bt)) {
+				type = base_complex_elem_type(bt);
+			} else {
+				switch (type->Basic.kind) {
+				case Basic_any:
+					switch (index) {
+					case 0: type = t_rawptr; break;
+					case 1: type = t_typeid; break;
+					}
+					break;
+				case Basic_string:
+					switch (index) {
+					case 0: type = t_u8_multi_ptr; break;
+					case 1: type = t_int;          break;
+					}
+					break;
+				}
+			}
+			break;
+		}
+	}
+	return type;
+}
+
 
 gb_internal gbString write_type_to_string(gbString str, Type *type, bool shorthand=false) {
 	if (type == nullptr) {