chore: leverage cargo's workspace inheritance

Previously, we would specify the version and path of our workspace dependencies in each of our crates. This is error prone as libp2p#3658 (comment) for example shows. Problems like these happened in the past too.

There is no need for us to ever depend on a earlier version than the most current one in our crates. It thus makes sense that we manage this version in a single place.

Cargo supports a feature called "workspace inheritance" which allows us to share a dependency declaration across a workspace and inherit it with `{ workspace = true }`.

We do this for all our workspace dependencies and for the MSRV.

Resolves libp2p#3787.

Pull-Request: libp2p#3715.

.github/workflows/cache-factory.yml

@@ -1,5 +1,7 @@
-# This workflow _produces_ caches which are used to speed up pull request builds.
-# The caches are split by Rust version (stable vs MSRV per crate) because those caches cannot share any artifacts.
+# This workflow _produces_ a cache that is used to speed up pull request builds.
+#
+# Our CI runs a job per crate, meaning all jobs share compilation artifacts but never the full cache.
+# Thus, we make a single cache here that is used by all jobs and the jobs only read from this cache.
 
 name: Cache factory
 
@@ -13,42 +15,6 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  gather_msrv_versions:
-    runs-on: ubuntu-latest
-    outputs:
-      versions: ${{ steps.find-rust-versions.outputs.versions }}
-    steps:
-      - uses: actions/checkout@v3
-
-      - id: find-rust-versions
-        run: |
-          RUST_VERSIONS=$(cargo metadata --format-version=1 --no-deps | jq -c '.packages | map(.rust_version) | unique | del(..|nulls)')
-          echo "versions=${RUST_VERSIONS}" >> $GITHUB_OUTPUT
-
-  make_msrv_cache:
-    runs-on: ubuntu-latest
-    needs: gather_msrv_versions
-    strategy:
-      fail-fast: false
-      matrix:
-        rust: ${{ fromJSON(needs.gather_msrv_versions.outputs.versions) }}
-    steps:
-      - uses: actions/checkout@v3
-
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: ${{ matrix.rust }}
-
-      - uses: Swatinem/rust-cache@6fd3edff6979b79f87531400ad694fb7f2c84b1f # v2.2.1
-        with:
-          shared-key: msrv-cache
-
-      - name: Compile all crates which have MSRV ${{ matrix.rust }}
-        run: |
-          cargo metadata --format-version=1 --no-deps | \
-          jq -r '.packages[] | select(.rust_version == "${{ matrix.rust }}") | "+\(.rust_version) build --all-features --package \(.name)"' |
-          xargs --verbose -L 1 cargo
-
   make_stable_rust_cache:
     runs-on: ubuntu-latest
     steps:

.github/workflows/ci.yml

@@ -32,32 +32,10 @@ jobs:
       - name: Install Protoc
         run: sudo apt-get install -y protobuf-compiler
 
-      - uses: dtolnay/rust-toolchain@stable
-
       - uses: actions/checkout@v3
 
-      - name: Get MSRV for ${{ matrix.crate }}
-        id: parse-msrv
-        run: |
-          RUST_VERSION=$(cargo metadata --format-version=1 --no-deps | jq -r '.packages[] | select(.name == "${{ matrix.crate }}") | .rust_version')
-          echo "version=${RUST_VERSION}" >> $GITHUB_OUTPUT
-        shell: bash
-
-      - name: Install Rust ${{ steps.parse-msrv.outputs.version }} for MSRV check
-        uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: ${{ steps.parse-msrv.outputs.version }}
-
       - uses: r7kamura/rust-problem-matchers@d58b70c4a13c4866d96436315da451d8106f8f08 #v1.3.0
 
-      - uses: Swatinem/rust-cache@6fd3edff6979b79f87531400ad694fb7f2c84b1f # v2.2.1
-        with:
-          shared-key: msrv-cache
-          save-if: false
-
-      - name: Check if ${{ matrix.crate }} compiles on MSRV (Rust ${{ steps.parse-msrv.outputs.version }})
-        run: cargo +${{ steps.parse-msrv.outputs.version }} build --package ${{ matrix.crate }} --all-features
-
       - uses: dtolnay/rust-toolchain@stable
 
       - uses: Swatinem/rust-cache@6fd3edff6979b79f87531400ad694fb7f2c84b1f # v2.2.1
@@ -90,6 +68,21 @@ jobs:
           cargo metadata --format-version=1 --no-deps | \
           jq -e -r '.packages[] | select(.name == "${{ matrix.crate }}") | .dependencies | all(.name != "libp2p")'
 
+      - uses: taiki-e/cache-cargo-install-action@7dd0cff2732612ac642812bcec4ada5a279239ed # v1
+        with:
+          tool: tomlq
+
+      - name: Enforce version in `workspace.dependencies` matches latest version
+        if: matrix.crate != 'libp2p'
+        run: |
+          PACKAGE_VERSION=$(cargo metadata --format-version=1 --no-deps | jq -e -r '.packages[] | select(.name == "${{ matrix.crate }}") | .version')
+          SPECIFIED_VERSION=$(tomlq 'workspace.dependencies.${{ matrix.crate }}.version' --file ./Cargo.toml)
+          
+          echo "Package version: $PACKAGE_VERSION";
+          echo "Specified version: $SPECIFIED_VERSION";
+
+          test "$PACKAGE_VERSION" = "$SPECIFIED_VERSION"
+
   cross:
     name: Compile on ${{ matrix.target }}
     strategy:
@@ -122,6 +115,30 @@ jobs:
 
       - run: cargo check --package libp2p --all-features --target=${{ matrix.target }}
 
+  msrv:
+    name: Compile with MSRV
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Extract MSRV from workspace manifest
+        shell: bash
+        run: |
+          MSRV=$(grep -oP 'rust-version\s*=\s*"\K[^"]+' Cargo.toml)
+          echo "MSRV=$MSRV" >> $GITHUB_ENV
+
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: ${{ env.MSRV }}
+
+      - uses: r7kamura/rust-problem-matchers@d58b70c4a13c4866d96436315da451d8106f8f08 #v1.3.0
+
+      - uses: Swatinem/rust-cache@6fd3edff6979b79f87531400ad694fb7f2c84b1f # v2.2.1
+        with:
+          save-if: ${{ github.ref == 'refs/heads/master' }}
+
+      - run: cargo +$MSRV check --workspace --all-features
+
   feature_matrix: # Test various feature combinations work correctly
     name: Compile with select features (${{ matrix.features }})
     runs-on: ubuntu-latest