- Bitstruct as substruct fails to properly work with designated initializers. #2827

releasenotes.md

@@ -127,6 +127,7 @@
 - Empty enums would return the values as zero sized arrays #2838
 - Store of zero in lowering did not properly handle optionals in some cases #2837
 - Bitstruct accidentally allowed other arrays than char arrays #2836
+- Bitstruct as substruct fails to properly work with designated initializers. #2827
 
 ### Stdlib changes
 - Add `ThreadPool` join function to wait for all threads to finish in the pool without destroying the threads.

src/compiler/sema_initializers.c

@@ -519,13 +519,11 @@ static bool sema_expr_analyse_designated_initializer(SemaContext *context, Type
 		}
 	}
 	Type *original = flattened->canonical;
-	bool is_bitstruct = original->type_kind == TYPE_BITSTRUCT;
+	bool is_structlike = type_is_union_or_strukt(original) || original->type_kind == TYPE_BITSTRUCT;
-	bool is_structlike = type_is_union_or_strukt(original) || is_bitstruct;
 	ArrayIndex max_index = -1;
 	bool optional = false;
 	Type *inner_type = NULL;
 	bool is_inferred = type_is_inferred(flattened);
-	int bitmember_count_without_value = 0;
 	FOREACH(Expr *, expr, init_expressions)
 	{
 		Decl *member;
@@ -535,10 +533,8 @@ static bool sema_expr_analyse_designated_initializer(SemaContext *context, Type
 		Expr *value = expr->designator_expr.value;
 		if (!value && is_bitmember && member->var.start_bit == member->var.end_bit && type_flatten(result) == type_bool)
 		{
-			ASSERT(is_bitstruct);
 			value = expr_new_const_bool(INVALID_SPAN, type_bool, true);
 			expr->designator_expr.value = value;
-			bitmember_count_without_value += 1;
 		}
 		if (!value) RETURN_SEMA_ERROR(expr, "This initializer needs a value.");
 		if (!sema_analyse_expr_rhs(context, result, value, true, no_match_ref, false)) return false;
@@ -553,10 +549,6 @@ static bool sema_expr_analyse_designated_initializer(SemaContext *context, Type
 			inner_type = type_no_optional(value->type);
 		}
 	}
-	if (bitmember_count_without_value != 0 && bitmember_count_without_value != vec_size(init_expressions))
-	{
-		RETURN_SEMA_ERROR(initializer, "Mixing the omission of initializers is not permitted.");
-	}
 	Type *type;
 	if (!is_structlike && is_inferred)
 	{

test/test_suite/bitstruct/bitstruct_designated_deep.c3t

@@ -0,0 +1,18 @@
+// #target: macos-x64
+module test;
+struct Foo4
+{
+    bitstruct : short
+    {
+        short expand : 1..7;
+        bool b : 8;
+    }
+}
+fn void main()
+{
+	Foo4 f4 = { .expand = 2, .b };
+}
+
+/* #expect: test.ll
+
+@.__const = private unnamed_addr constant %Foo4 { i16 260 }, align 2

test/test_suite/bitstruct/bitstruct_init.c3

@@ -91,12 +91,10 @@ fn void test4()
     Flags1 flags1 = {.a, .b, .c};
     flags1 = {.a};
     flags1 = {.a = true, .b = true, .c = false};
-    flags1 = {.a, .b = true, .c = true}; // #error: Mixing the omission
     Foo foo = { .x = 0, .z }; // #error: needs a value
 
     Flags2 flags2 = {.b, .d};
     flags2 = {.b, .c, .d}; // #error: needs a value
-    flags2 = {.a, .c = 1, .d}; // #error: Mixing the omission
 
     Flags2_Struct flags2s;
     flags2s = {.b, .c, .d}; // #error: needs a value