#cfg conditional compilation does not work in object expressions

[boggle]

Likely, this also holds for non toplevel functions. It is inconvenient and probably should be fixed. Example from io.rs:

obj FILE_writer(f: os::libc::FILE, res: option::t@FILE_res) {
#cfg[target="macos"]
fn fsync() { ret macos_os::fsync(f); }
}

will not compile.

[brson]

This is because attributes only work on items, and objects and methods are not items. Probably the best you can do in this situation is define a function inside the fsync method and conditionalize that. I believe that will work.

obj FILE_writer(f: os::libc::FILE, res: option::t<@FILE_res>) {
  fn fsync() {
    fsync_()

    #[cfg(target_os = "macos")]
    fn fsync_() {  macos_os::fsync(f) }

    ...
  }
}

It probably would not be difficult to allow attributes and conditional compilation on methods as well. Attributes on general expressions is harder.

[graydon]

obj doesn't exist anymore, closing.