ci: read MSRV from manifest (#559)

Author: robjtede

.github/workflows/ci.yml

@@ -13,7 +13,14 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  read_msrv:
+    name: Read MSRV
+    uses: actions-rust-lang/msrv/.github/workflows/msrv.yml@main
+
   build_and_test:
+    needs:
+      - read_msrv
+
     strategy:
       fail-fast: false
       matrix:
@@ -24,7 +31,7 @@ jobs:
           - { name: Windows, os: windows-latest, triple: x86_64-pc-windows-msvc }
           - { name: Windows (MinGW), os: windows-latest, triple: x86_64-pc-windows-gnu }
         version:
-          - { name: msrv, version: 1.70.0 }
+          - { name: msrv, version: "${{ needs.read_msrv.outputs.msrv }}" }
           - { name: stable, version: stable }
 
     name: ${{ matrix.target.name }} / ${{ matrix.version.name }}

justfile

@@ -27,6 +27,13 @@ all_crate_features := if os() == "linux" {
     "--features='" + non_linux_all_features_list + "'"
 }
 
+m:
+    cargo metadata --format-version=1 \
+    | jq -r 'first(.packages[] | select(.source == null)) | .rust_version' \
+    | sed -E 's/^1\.([0-9]{2})$/1\.\1\.0/' \
+    | xargs -0 printf "msrv=%s" \
+    | tee /dev/stderr
+
 # Test workspace code.
 test toolchain="":
     cargo {{ toolchain }} test --lib --tests --package=actix-macros