rustbuild: error while trying to run tests incrementally

[achanda]

I cloned rust, built it by running ./x.py build --incremental. Later I pulled new changes and ran that again. Now when I try to run ./x.py test --incremental, I see

   Compiling rustbook v0.0.0 (file:///Users/Abhishek/src/rust/src/tools/rustbook)
error[E0460]: found possibly newer version of crate `collections` which `rustdoc` depends on
  --> src/tools/rustbook/main.rs:16:1
   |
16 | extern crate rustdoc;
   | ^^^^^^^^^^^^^^^^^^^^^
   |
   = note: perhaps that crate needs to be recompiled?
   = note: crate `collections` path #1: /Users/Abhishek/src/rust/build/x86_64-apple-darwin/stage1/lib/rustlib/x86_64-apple-darwin/lib/libcollections-1880f463631511fa.rlib
   = note: crate `rustdoc` path #1: /Users/Abhishek/src/rust/build/x86_64-apple-darwin/stage1/lib/rustlib/x86_64-apple-darwin/lib/librustdoc-9da233d729b34bfc.dylib

error: aborting due to previous error

error: Could not compile `rustbook`.

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


command did not execute successfully: "/Users/Abhishek/.cargo/bin/cargo" "build" "-j" "8" "--target" "x86_64-apple-darwin" "--release" "--manifest-path" "/Users/Abhishek/src/rust/src/tools/rustbook/Cargo.toml"
expected success, got: exit code: 101

[aidanhs]

cc #37929

Note that (as far as I can tell) you don't have to pull changes for this to happen (which could do all sorts of changes), you just need to a) clean incremental build, b) make a tiny change to libcollections c) incremental build.

[aidanhs]

Seems to be fixed by #38809

[alexcrichton]

Yay!