PartialRange

        const PartialRange = struct {
            line_offset: i32,
            file_id: ?u32,
            code_offset: u32,
            code_length: ?u32,

            /// Resolves a partial range to a range with a definite length, or returns null if this
            /// is not possible.
            fn resolve(self: PartialRange, next_code_offset: ?u32) ?Range {
                return .{
                    .line_offset = self.line_offset,
                    .file_id = self.file_id,
                    .code_offset = self.code_offset,
                    .code_length = b: {
                        if (self.code_length) |l| break :b l;
                        const end = next_code_offset orelse return null;
                        break :b end - self.code_offset;
                    },
                };
            }
        }