x.py dist shouldn’t require network access

[Keruspe]

Since #78790 we run cargo vendor unconditionally to vendor libtest in libstd.
We should either pass it '--offline' or add a way to conditionally do so to avoid using network when unnecessary

[Mark-Simulacrum]

I am happy to accept a patch for this; if it is not small (e.g., just adding offline) we will likely end up wanting to revert #78790 on beta.

[camelid]

Is this really P-critical? I would think this is P-high since P-critical is usually reserved for severe user-facing bugs.

[Mark-Simulacrum]

I consider inability for distros to build a particular version of Rust to be a release blocker.

[Keruspe]

Here what i've tried so far:

• cargo vendor --offline
• cargo vendor --locked
• cargo generate-lockfile --offline && cargo vendor --locked
• cargo generate-lockfile --offline && cargo vendor --locked --offline

None of those worked out, last failure:

running: "/usr/x86_64-pc-linux-gnu/bin/cargo-beta" "generate-lockfile" "--offline"
running: "/usr/x86_64-pc-linux-gnu/bin/cargo-beta" "vendor" "--offline" "--locked" "/var/tmp/paludis/build/dev-lang-rust-1.49.0-scm/work/rust-1.49.0-scm/build/tmp/dist/rust-src-beta-image/lib/rustlib/src/rust/vend
or"
                                                                                                 
command did not execute successfully: "/usr/x86_64-pc-linux-gnu/bin/cargo-beta" "vendor" "--offline" "--locked" "/var/tmp/paludis/build/dev-lang-rust-1.49.0-scm/work/rust-1.49.0-scm/build/tmp/dist/rust-src-beta-im
age/lib/rustlib/src/rust/vendor"
expected success, got: exit code: 101                                                                              
error: failed to sync            
Caused by:                   
  failed to download packages                                                               
Caused by:               
  failed to download `rustc-std-workspace-alloc v1.0.0`
Caused by:                                                                                                                                                                                                           
  can't make HTTP request in the offline mode   

[Keruspe]

With just the cargo vendor --locked --offline (without the generate-lockfile):

Caused by:
  failed to load pkg lockfile                                                                                                                                   
Caused by:                                                                                                
  can't update in the offline mode

[camelid]

I consider inability for distros to build a particular version of Rust to be a release blocker.

Ah, I didn't realize it was that bad! Sorry about that.

[Mark-Simulacrum]

cc @rust-lang/cargo -- do we expect cargo vendor to work without network when vendoring a subset of a workspace? It looks like we're running into some trouble here to get it working, though I've not personally had time yet to test.

cc @Gankra as well

[alexcrichton]

I believe Cargo is working as intended here, when you run cargo vendor in the workspace root it doesn't actually vendor the rustc-std-workspace-* crates from crates.io because they're patched locally to the in-tree versions. Then when Cargo later vendors for libtest, it doesn't see the [patch] annotations so it tries to download them from the network. If you've passed --offline and you're using a vendor directory that means Cargo can't download any more packages, so it provides this error.

I think the fix here is to either get Cargo to see the [patch] for these crates during the libtest vendoring process or somehow get those crates vendored in whatever does the original vendor.

[Keruspe]

Will give the [patch] approach a try, thanks a lot for the explanation

edit: assuming adding the patch section to e.g. libtest Cargo.toml can work