Auto merge of #3036 - RalfJung:josh-autostart, r=RalfJung

automatically start and stop josh in rustc-pull/push

Let's make use of the fact that this is not a shell script any more. :)

Author: bors

.github/workflows/ci.yml

@@ -189,8 +189,6 @@ jobs:
           fetch-depth: 256 # get a bit more of the history
       - name: install josh-proxy
         run: cargo +stable install josh-proxy --git https://github.com/josh-project/josh --tag r22.12.06
-      - name: start josh-proxy
-        run: josh-proxy --local=$HOME/.cache/josh --remote=https://github.com --no-background &
       - name: setup bot git name and email
         run: |
           git config --global user.name 'The Miri Conjob Bot'

CONTRIBUTING.md

@@ -231,25 +231,16 @@ You can also directly run Miri on a Rust source file:
 ## Advanced topic: Syncing with the rustc repo
 
 We use the [`josh` proxy](https://github.com/josh-project/josh) to transmit changes between the
-rustc and Miri repositories.
+rustc and Miri repositories. You can install it as follows:
 
 ```sh
 cargo +stable install josh-proxy --git https://github.com/josh-project/josh --tag r22.12.06
-josh-proxy --local=$HOME/.cache/josh --remote=https://github.com --no-background
 ```
 
-This uses a directory `$HOME/.cache/josh` as a cache, to speed up repeated pulling/pushing.
-
-To make josh push via ssh instead of https, you can add the following to your `.gitconfig`:
-
-```toml
-[url "git@github.com:"]
-    pushInsteadOf = https://github.com/
-```
+Josh will automatically be started and stopped by `./miri`.
 
 ### Importing changes from the rustc repo
 
-Josh needs to be running, as described above.
 We assume we start on an up-to-date master branch in the Miri repo.
 
 ```sh
@@ -268,16 +259,14 @@ needed.
 
 ### Exporting changes to the rustc repo
 
-Keep in mind that pushing is the most complicated job that josh has to do --
-pulling just filters the rustc history, but pushing needs to construct a new
-rustc history that would filter to the given Miri history! To avoid problems, it
-is a good idea to always pull immediately before you push. In particular, you
-should never do two josh pushes without an intermediate pull; that can lead to
-duplicated commits.
+Keep in mind that pushing is the most complicated job that josh has to do -- pulling just filters
+the rustc history, but pushing needs to construct a new rustc history that would filter to the given
+Miri history! To avoid problems, it is a good idea to always pull immediately before you push. If
+you are getting strange errors, chances are you are running into [this josh
+bug](https://github.com/josh-project/josh/issues/998). In that case, please get in touch on Zulip.
 
-Josh needs to be running, as described above. We will use the josh proxy to push
-to your fork of rustc. Run the following in the Miri repo, assuming we are on an
-up-to-date master branch:
+We will use the josh proxy to push to your fork of rustc. Run the following in the Miri repo,
+assuming we are on an up-to-date master branch:
 
 ```sh
 # Push the Miri changes to your rustc fork (substitute your github handle for YOUR_NAME).
@@ -287,3 +276,11 @@ up-to-date master branch:
 This will create a new branch called 'miri' in your fork, and the output should
 include a link to create a rustc PR that will integrate those changes into the
 main repository.
+
+If this fails due to authentication problems, it can help to make josh push via ssh instead of
+https. Add the following to your `.gitconfig`:
+
+```toml
+[url "git@github.com:"]
+    pushInsteadOf = https://github.com/
+```

miri-script/Cargo.lock

@@ -20,3 +20,4 @@ anyhow = "1.0"
 xshell = "0.2"
 rustc_version = "0.4"
 dunce = "1.0.4"
+directories = "4"