dev-lang/rust-9999 - cargo clippy: error[E0463]: can't find crate for core

[negge]

Redirected here from https://bugs.gentoo.org/667026

After emerging rust-9999 with clippy useflag on, running "cargo clippy" fails with:

$ cargo clippy
    Checking libc v0.2.43                                                                                                                                                         
    Checking unicode-width v0.1.5                                                                                                                                                 
    Checking bitflags v1.0.4                                                                                                                                                      
    Checking cfg-if v0.1.5                                                                                                                                                        
error[E0463]: can't find crate for `core`                                                                                                                                         
                                                                                                                                                                                  
error: aborting due to previous error                                                                                                                                             
                                                                                                                                                                                  
For more information about this error, try `rustc --explain E0463`.                                                                                                               
error: Could not compile `cfg-if`.                                                                                                                                                
warning: build failed, waiting for other jobs to finish...
error[E0463]: can't find crate for `std`                                                                                                                                          
                                                                                                                                                                                  
error: aborting due to previous error                                                                                                                                             
                                                                                                                                                                                  
For more information about this error, try `rustc --explain E0463`.                                                                                                               
error[E0463]: can't find crate for `core`                                                                                                                                         
                                                                                                                                                                                  
error: aborting due to previous error                                                                                                                                             
                                                                                                                                                                                  
For more information about this error, try `rustc --explain E0463`.                                                                                                               
error: Could not compile `libc`.                                                                                                                                                  
warning: build failed, waiting for other jobs to finish...
error: Could not compile `bitflags`.                                                                                                                                              
warning: build failed, waiting for other jobs to finish...
error[E0463]: can't find crate for `core`                                                                                                                                         
                                                                                                                                                                                  
error: aborting due to previous error                                                                                                                                             
                                                                                                                                                                                  
For more information about this error, try `rustc --explain E0463`.                                                                                                               
error: Could not compile `unicode-width`.                                                                                                                                         

To learn more, run the command again with --verbose.

[o01eg]

There is a workaround: rust-lang/rust-clippy#2874

[lu-zero]

Probably RUSTFLAGS should be set by eselect and part of the env.

We should ask cargo upstream to make it aware of how the toolchain is packaged to make the whole thing transparent (and be instruction compatible e.g. cargo +nightly does not work for us).

[cardoe]

Well cargo +nightly is a syntax parsed by rustup not cargo. Gentoo could have stubs installed for rustc, cargo, etc that implement the necessary functionality.

[o01eg]

Actually it's a bug which isn't drawn attention clippy team to. Custom libdir had worked in clippy but was broken sometime.

[o01eg]

I've managed to fix it in #372 . Use EGIT_OVERRIDE_COMMIT_RUST_LANG_RUST=2bd5993ca25e09b894e4fd6539a2fba64599eee2 due clippy broken in master rust https://rust-lang-nursery.github.io/rust-toolstate/