Merge pull request #2003 from EliahKagan/run-ci/msrv-check

Improve MSRV check and fix `aria-label` in MSRV badge

Author: EliahKagan

.github/workflows/ci.yml

@@ -433,7 +433,8 @@ jobs:
 
     defaults:
       run:
-        shell: bash  # Use bash even on Windows, if we ever reenable windows-latest for testing.
+        # Use `bash` even on Windows, if we ever reenable `windows-latest` for testing.
+        shell: bash
 
     steps:
       - uses: actions/checkout@v4

.github/workflows/msrv.yml

@@ -29,15 +29,21 @@ jobs:
     runs-on: ${{ matrix.os }}
 
     env:
-      # dictated by `firefox` to support the `helix` editor, but now probably effectively be controlled by `jiff`, which also aligns with `regex`.
-      # IMPORTANT: adjust etc/msrv-badge.svg as well
-      rust_version: 1.75.0
+      # This is dictated by `firefox` to support the `helix` editor, but now probably effectively
+      # be controlled by `jiff`, which also aligns with `regex`.
+      # IMPORTANT: When adjusting, change all occurrences in `etc/msrv-badge.svg` as well.
+      RUST_VERSION: 1.75.0
 
     steps:
       - uses: actions/checkout@v4
       - uses: extractions/setup-just@v3
-      - run: |
-          rustup toolchain install ${{ env.rust_version }} nightly --profile minimal --no-self-update
-          rustup default ${{ env.rust_version }}
+      - name: Set up ${{ env.RUST_VERSION }} (MSRV) and nightly toolchains
+        run: rustup toolchain install ${{ env.RUST_VERSION }} nightly --profile minimal --no-self-update
+      - name: Set ${{ env.RUST_VERSION }} (MSRV) as default
+        run: rustup default ${{ env.RUST_VERSION }}
+      - name: Downgrade locked dependencies to lowest allowed versions
+        run: |
+          # TODO(msrv): Use `cargo update --minimal-versions` when `--minimal-versions` is available.
           cargo +nightly update -Zminimal-versions
-      - run: just ci-check-msrv
+      - name: Run some `cargo build` commands on `gix`
+        run: just ci-check-msrv

Makefile

@@ -126,8 +126,8 @@ bench-gix-config:
 
 check-msrv-on-ci: ## Check the minimal support rust version for currently installed Rust version
 	rustc --version
-	cargo check --package gix
-	cargo check --package gix --no-default-features --features async-network-client,max-performance
+	cargo build --locked --package gix
+	cargo build --locked --package gix --no-default-features --features async-network-client,max-performance
 
 ##@ Maintenance
 

etc/msrv-badge.svg

@@ -238,11 +238,16 @@ cross-test-android: (cross-test 'armv7-linux-androideabi' '--no-default-features
 check-size:
     etc/check-package-size.sh
 
-# Check the minimal support Rust version, with the currently installed Rust version
+# This assumes the current default toolchain is the Minimal Supported Rust Version and checks
+# against it. This is run on CI in `msrv.yml`, after the MSRV toolchain is installed and set as
+# default, and after dependencies in `Cargo.lock` are downgraded to the latest MSRV-compatible
+# versions. Only if those or similar steps are done first does this work to validate the MSRV.
+#
+# Check the MSRV, *if* the toolchain is set and `Cargo.lock` is downgraded (used on CI)
 ci-check-msrv:
     rustc --version
-    cargo check -p gix
-    cargo check -p gix --no-default-features --features async-network-client,max-performance
+    cargo build --locked -p gix
+    cargo build --locked -p gix --no-default-features --features async-network-client,max-performance
 
 # Enter a nix-shell able to build on macOS
 nix-shell-macos: