failUnexpected

    fn failUnexpected(
        self: @This(),
        T: type,
        item_kind: []const u8,
        node: Zoir.Node.Index,
        field: ?usize,
        name: []const u8,
    ) error{ OutOfMemory, ParseZon } {
        @branchHint(.cold);
        if (self.diag == null) return error.ParseZon;
        const gpa = self.gpa;
        const token = if (field) |f| b: {
            var buf: [2]Ast.Node.Index = undefined;
            const struct_init = self.ast.fullStructInit(&buf, node.getAstNode(self.zoir)).?;
            const field_node = struct_init.ast.fields[f];
            break :b self.ast.firstToken(field_node) - 2;
        } else self.ast.nodeMainToken(node.getAstNode(self.zoir));
        switch (@typeInfo(T)) {
            inline .@"struct", .@"union", .@"enum" => |info| {
                const note: Error.TypeCheckFailure.Note = if (info.field_names.len == 0) b: {
                    break :b .{
                        .token = token,
                        .offset = 0,
                        .msg = "none expected",
                        .owned = false,
                    };
                } else b: {
                    const msg = "supported: ";
                    var buf: std.ArrayList(u8) = try .initCapacity(gpa, 64);
                    defer buf.deinit(gpa);
                    try buf.appendSlice(gpa, msg);
                    inline for (info.field_names, 0..) |field_name, i| {
                        if (i != 0) try buf.appendSlice(gpa, ", ");
                        try buf.print(gpa, "'{f}'", .{std.zig.fmtIdFlags(field_name, .{
                            .allow_primitive = true,
                            .allow_underscore = true,
                        })});
                    }
                    break :b .{
                        .token = token,
                        .offset = 0,
                        .msg = try buf.toOwnedSlice(gpa),
                        .owned = true,
                    };
                };
                return self.failTokenFmtNote(
                    token,
                    0,
                    "unexpected {s} '{s}'",
                    .{ item_kind, name },
                    note,
                );
            },
            else => comptime unreachable,
        }
    }