RA doesn't seem to respect cfg on fields

[Lokathor]

pub struct ZlibByteIter<'s> {
  pub(crate) current: &'s [u8],
  pub(crate) idat_iter: IdatIter<'s>,
  #[cfg(not(feature = "png_skip_adler_checks"))]
  pub(crate) adler: u32,
}

impl<'s> ZlibByteIter<'s> {
  fn from_current_and_iter(current: &'s [u8], idat_iter: IdatIter<'s>) -> Self {
    #[cfg(not(feature = "png_skip_adler_checks"))]
    {
      Self { current, idat_iter, adler: 1 }
    }
    #[cfg(feature = "png_skip_adler_checks")]
    {
      Self { current, idat_iter }
    }
  }
}

This will report the second cfg variant as missing the adler field, which doesn't exist under that configuration.

[bjorn3]

I think this should have been fixed by #3880, but that PR was merged 11 days ago.

[Lokathor]

It seems I have, rust-analyzer version: 2020-04-13 (c388130), which is newer than 11 days ago if my math is right

[edwin0cheng]

which doesn't exist under that configuration.

What's your rust-analyzer.cargo.features settings ?

[flodiebold]

I think the problem might rather be that we don't support cfg on blocks (or do we?) 🤔

[bnjjj]

For now cfg is partially supported on struct fields, and function as far as I remember. And when I say partially it's mainly because it just check the default features in your cargo.toml. I think it should work with this kind of syntax:

pub struct ZlibByteIter<'s> {
  pub(crate) current: &'s [u8],
  pub(crate) idat_iter: IdatIter<'s>,
  #[cfg(not(feature = "png_skip_adler_checks"))]
  pub(crate) adler: u32,
}

impl<'s> ZlibByteIter<'s> {
  fn from_current_and_iter(current: &'s [u8], idat_iter: IdatIter<'s>) -> Self {
      Self {
          current,
          idat_iter,
          #[cfg(not(feature = "png_skip_adler_checks"))]
          adler: 1
     }
  }
}

Or you can also have 2 methods fn from_current_and_iter(current: &'s [u8], idat_iter: IdatIter<'s>) -> Self on with the feature flag enabled and another one without. Because for now we don't support cfg attributes on block.

I will try to implement it in the next days :)

@Lokathor let me know if these workarounds are working :)

[lnicola]

Closed by #4063.