Re: Rust 1.19 fails to build on i686 on ‘staging’

[Ludovic Courtès]

Hi Danny,

Danny Milosavljevic <address@hidden> skribis:

> On Mon, 28 Jan 2019 15:39:33 +0100
> Ludovic Courtès <address@hidden> wrote:
>> > /gnu/store/fw4yy7cgb5ahs9s2ir00bawnsl5zj7db-mrustc-0.8.0/bin/mrustc[...]
>> munmap_chunk(): invalid pointer
>
> Maybe the above causes
>
>> src/tools/cargo/src/crates-io/lib.rs:65: BUG:src/expand/proc_macro.cpp:941: 
>> Unexpected EOF while reading from child process
>
> this.
>
> Might be a memory double-free.  Exactly the kind of thing that Rust is 
> supposed
> to prevent is in the Rust compiler in C++ - well, at least the motivation for
> having Rust is clear now ;-)

Heh, sounds like it.

> Can you try just
>
> $ /gnu/store/fw4yy7cgb5ahs9s2ir00bawnsl5zj7db-mrustc-0.8.0/bin/mrustc 
> src/tools/cargo/src/crates-io/lib.rs --crate-name crates_io --crate-type rlib 
> --crate-tag 0_9_0 -g --cfg debug_assertions -O -o 
> output/cargo-build/libcrates_io-0_9_0.hir -L output/cargo-build --extern 
> curl=output/cargo-build/libcurl-0_4_6.hir --extern 
> error_chain=output/cargo-build/liberror_chain-0_10_0.hir --extern 
> serde=output/cargo-build/libserde-1_0_6.hir --extern 
> serde_derive=output/cargo-build/libserde_derive-1_0_6.hir --extern 
> serde_json=output/cargo-build/libserde_json-1_0_2.hir --extern 
> url=output/cargo-build/liburl-1_4_0.hir -L output -L 
> /gnu/store/fw4yy7cgb5ahs9s2ir00bawnsl5zj7db-mrustc-0.8.0/lib/mrust
>
> in the build-failed kept source? (possibly with "ulimit -c unlimited" so it 
> dumps core. mrustc is a normal C++ program, so normal debugging ways apply)
>
> Or do I have access to the machine so I can do it?

I don’t know but you could try:

  guix build address@hidden -s i686-linux -K

on your x86_64 machine from ‘staging’, and hopefully you’ll get that
error too.

> Possible use-after free fix in mrustc commits:
>
> https://github.com/thepowersgang/mrustc/commit/a51eea542ae086687ea2c4cb09321785f5cc6269

Could be!  We know what to try next.

Thanks for investigating!

Ludo’.