stack overflow in impl Writer for &mut Writer

[stepancheg]

Code:

use std::io;

struct Bar<'a> {
    writer: Option<&'a mut Writer + 'a>,
}

fn foo<'a>(mut bar: Bar<'a>) {
    match bar.writer {
        Some(ref mut w) => { w.write([]); },
        _ => {},
    }
}

fn main() {
    foo(Bar {
        writer: Some(&mut io::stdout() as &mut Writer),
    })
}

Compile, run, result is

task '<main>' has overflowed its stack

Sorry, cannot find smaller example to reproduce the problem.

$ rustc --version
rustc 0.12.0-nightly (136ab3c6b 2014-10-04 00:17:04 +0000)
$ uname -a
Linux precise64 3.2.0-23-generic #36-Ubuntu SMP Tue Apr 10 20:39:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

Similar code, internal compiler error:

use std::io;

struct Bar<'a> {
    writer: Option<&'a mut Writer + 'a>,
}

fn baz(_: &mut Writer) {
}

fn foo<'a>(mut bar: Bar<'a>) {
    baz(bar.writer.as_mut().unwrap());
}

fn main() {
    foo(Bar {
        writer: Some(&mut io::stdout() as &mut Writer),
    })
}

error: internal compiler error: trying to take the sizing type of std::io::Writer+'a, an unsized type

[mahkoh]

Smaller:

use std::io;

fn main() {
    let ref mut w = &mut io::stdout() as &mut Writer;
    w.write([]);
}

[bkoropoff]

Looks like a libstd bug:

impl<'a> Writer for &'a mut Writer+'a {
    #[inline]
    fn write(&mut self, buf: &[u8]) -> IoResult<()> { self.write(buf) }

    #[inline]
    fn flush(&mut self) -> IoResult<()> { self.flush() }
}

@stepancheg, could you file a separate issue for the internal compiler error?

[stepancheg]

@bkoropoff #17771