fix: map relative path to protocol circuits (AztecProtocol#3694)

This PR fixes an issue with how we mirror code in the monorepo to
aztecprotocol/aztec-nr.

A while back the root aztec library added a dependency on
noir-protocol-circuits. In the monorepo this is achieved by use of a
relative path in Nargo.toml. This works fine for contracts that pull in
Aztec.nr through the monorepo (see also AztecProtocol#3604) but it breaks projects
that use
[AztecProtocol/aztec-nr](https://github.com/AztecProtocol/aztec-nr)
because the relative path won't exist in the mirrored repo.

What this PR does is map any relative dependencies to protocol circuits
to a git dependency before pushing that commit to the mirrored repo. It
then undoes this change before pushing to the monorepo (we want to keep
using relative paths in the monorepo).

I would've preferred using `yq` since it claims it suports TOML (and is
included in the default Github actions package list) but its support is
limited to only basic types (so no objects like `{path="..."}`) and it
can only read toml but not write it.

mikefarah/yq#1364 (comment)

.github/workflows/mirror_repos.yml

@@ -9,7 +9,7 @@ name: Mirror Repositories
 on:
   schedule:
     # Run the workflow every night at 2:00 AM UTC.
-    - cron: '0 2 * * *'
+    - cron: "0 2 * * *"
 
 jobs:
   mirror-to-build-system-repo:
@@ -72,9 +72,33 @@ jobs:
           git config --global user.name AztecBot
           git config --global user.email tech@aztecprotocol.com
 
+          monorepo_url="$GITHUB_SERVER_URL/$GITHUB_REPOSITORY"
+          # list all aztec-packages tags, take the "highest" version
+          monorepo_tag="$(git tag --list aztec-packages-v* | sort --version-sort | tail -1)"
+          monorepo_protocol_circuits_path="yarn-project/noir-protocol-circuits"
+          nargo_file="$SUBREPO_PATH/aztec/Nargo.toml"
+
+          # match lines like this:
+          # protocol_types = { path = "../../noir-protocol-circuits/src/crates/types" }
+          # and replace with
+          # protocol_types = { git="https://github.com/aztecprotocol/aztec-packages", tag="aztec-packages-v0.16.9", directory="yarn-project/noir-protocol-circuits/src/crates/types" }
+          sed --regexp-extended --in-place \
+            "s;path\s*=\s*\".*noir-protocol-circuits(.*)\";git=\"$monorepo_url\", tag=\"$monorepo_tag\", directory=\"$monorepo_protocol_circuits_path\1\";" \
+            $nargo_file
+
+          git commit --all --message "chore: replace relative paths to noir-protocol-circuits"
+
           if ./scripts/git_subrepo.sh push $SUBREPO_PATH --branch=master; then
             git fetch # in case a commit came after this
             git rebase origin/master
-            git commit --amend -m "$(git log -1 --pretty=%B) [skip ci]"
+
+            # restore old Nargo.toml
+            # We have to go back two generations. History looks like this:
+            # HEAD   <--- the commit generated by git_subrepo
+            # HEAD~1 <--- the chore commit created above
+            # HEAD~2 <--- the original commit we were supposed to mirror or the tip of master after rebase
+            git restore --source=HEAD~2 -- $nargo_file
+            git commit --all --amend -m "$(git log -1 --pretty=%B) [skip ci]"
+
             git push
           fi