Installation is broken when custom relative libdir path starts with lib/ or when libdir is changed during installation

[jauhien]

Gentoo uses installation of multiple rust versions side by side based on the possibility to install libraries to custom locations. At the moment because of this bug (its first part) we need to apply patch.

Steps to reproduce bug.

Case when custom libdir works

We are installing to /home/jauhien/w/image-working, libraries go to /home/jauhien/w/image-working/customrust.

1. Configure rust

   ./configure --prefix=/home/jauhien/w/image-working --libdir=/home/jauhien/w/image-working/customrust --disable-debug --disable-valgrind --disable-helgrind --disable-valgrind-rpass --enable-debuginfo-tests --disable-llvm-assertions --disable-debug-assertions --disable-debug-jemalloc --disable-debuginfo
   

2. Make rust

   make -j5
   

   Have some coffee or tea.

3. Install rust

   make install
   

Rust is installed and works. Libraries go to /home/jauhien/w/image-working/customrust as expected.

Case when custom libdir leads to failure (bug)

We are going to install rust into /home/jauhien/w/image, libraries will go to /home/jauhien/w/image/lib/customrust.

1. Configure rust
   ./configure --prefix=/home/jauhien/w/image --libdir=/home/jauhien/w/image/lib/customrust --disable-debug --disable-valgrind --disable-helgrind --disable-valgrind-rpass --enable-debuginfo-tests --disable-llvm-assertions --disable-debug-assertions --disable-debug-jemalloc --disable-debuginfo

Steps 2 and 3 as in the previous case.

Result: libraries are installed in /home/jauhien/w/image/lib/customrust/customrust. Note the customrust being repeated twice. Reason: lines in installer removed by mentioned patch.

Changing libdir during installation is broken

Libdir option for installer makes no sense as it is anyway broken.

Working installation using unchanged libdir

1. Download rust binary tarball for your arch and unpack it.

2. Install rust

   ./install.sh --prefix=/home/jauhien/w/image-bin-working
   

3. Try if it works

   jauhien@jauhien-VirtualBox rust-tmp % LD_LIBRARY_PATH=/home/jauhien/w/image-bin-working/lib ../image-bin-working/bin/rustc -V             
   rustc 1.3.0 (9a92aaf19 2015-09-15)                                                                                         
   jauhien@jauhien-VirtualBox rust-tmp % cat test.rs
   fn main() {
      println!("It works!");
   }
   jauhien@jauhien-VirtualBox rust-tmp % LD_LIBRARY_PATH=/home/jauhien/w/image-bin-working/lib ../image-bin-working/bin/rustc -V
   rustc 1.3.0 (9a92aaf19 2015-09-15)                                                                                   
   jauhien@jauhien-VirtualBox rust-tmp % ./test
   It works!
   

Broken installation when libdir option is used

1. As in previous case

2. Install rust

   ./install.sh --prefix=/home/jauhien/w/image-bin --libdir=/home/jauhien/w/image-bin/customrust
   

3. Try if it works

   jauhien@jauhien-VirtualBox rust-tmp % LD_LIBRARY_PATH=/home/jauhien/w/image-bin/customrust ../image-bin/bin/rustc -V        
   rustc 1.3.0 (9a92aaf19 2015-09-15)                                                                                
   jauhien@jauhien-VirtualBox rust-tmp % LD_LIBRARY_PATH=/home/jauhien/w/image-bin/customrust ../image-bin/bin/rustc test.rs -o test
   test.rs:1:1: 1:1 error: can't find crate for `std`                                                          
   test.rs:1 fn main() {
            ^
   error: aborting due to previous error
   
   

Reason: relative libdir path is captured by rust compiler during build and it is impossible to change it later.

[jauhien]

See also https://internals.rust-lang.org/t/perfecting-rust-packaging/2623/41

[anguslees]

I think this is a dup of #22831 - the latter was closed due to "inactivity", and I couldn't find the button to reopen it :/

[steveklabnik]

Anyone with commit can re-open it, if you're interested in reviving the PR, @anguslees , I'd be happy to do so

[jauhien]

@steveklabnik: #22831 doesn't fix this problem in general. I even doubt that it will work (cause it fixies installation, but I'm not sure that it will not break compilation). And anyway it does not address the problem No. 2 -- broken installation when libdir is changed in the install phase.

What I think we should do now is removing of --libdir parameter from the install script as it makes no sense and is broken anyway. This will correctly fix problem No. 1. Then, if for some reason somebody is interested in the changing of libdir during installation, he can try to fix this problem. The right way to fix it can be using of standard system mechanism for library lookup during looking for std crate in place of the one that we have now.

[brson]

My current preferred solution is to simply remove the --libdir option from rust-installer since it is so broken. That would leave the working case where --libdir is specified to the configure script, but make it uncustomizable at install-time with the normal installers.

Then we'll just wait until somebody complains hard about needing the installer to actually be able to do this customization.

[steveklabnik]

My understanding is that packaging has moved significantly forward in the 17 months since this bug has been commented on, and including gentoo: https://wiki.gentoo.org/wiki/Project:Rust

As such, I'm gonna assume this is stale, and give it a close. If not, please open a new bug. Thanks!