Reduce MSRV for zerofrom back to 1.71.1 (#6312)

As discussed in
#6192 (comment).

Author: djc

.github/workflows/build-test.yml

@@ -76,6 +76,30 @@ jobs:
     - name: Check
       run: cargo make ci-job-msrv-${{ matrix.behavior }}
 
+  msrv-zerofrom:
+    runs-on: ubuntu-latest
+    # Defined as a matrix so that features can start immediately, but
+    # be killed if check fails.
+    strategy:
+      fail-fast: true
+    # Set CARGO_HTTP_MULTIPLEXING=false to work around crates.io curl bug:
+    # <https://rust-lang.zulipchat.com/#narrow/stream/246057-t-cargo/topic/timeout.20investigation>
+    env:
+      CARGO_HTTP_MULTIPLEXING: false
+    steps:
+    - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
+
+    # Cargo-make boilerplate
+    - name: Install cargo-make
+      uses: taiki-e/install-action@64e4e2f995104968c78bd697b253d55bf557af66 # v2.41.11
+      with:
+        tool: [email protected]
+
+    # No toolchain boilerplate as this runs on MSRV
+
+    # Actual job
+    - name: Check
+      run: cargo make ci-job-msrv-zerofrom
 
   # ci-job-test
   test:

Makefile.toml

@@ -65,6 +65,16 @@ exec --fail-on-error rustup install 1.81 --profile minimal
 exec --fail-on-error cargo +1.81 check --all-targets --all-features
 '''
 
+[tasks.ci-job-msrv-zerofrom]
+description = "Run MSRV tests for the zerofrom MSRV job"
+category = "ICU4X Development"
+env = { ICU4X_DATA_DIR = "../stubdata" }
+script_runner = "@duckscript"
+script = '''
+exec --fail-on-error rustup install 1.71.1 --profile minimal
+exec --fail-on-error cargo +1.71.1 check -p zerofrom --all-targets --all-features
+'''
+
 [tasks.ci-job-test]
 description = "Run all tests for the CI 'test' job"
 category = "CI"

utils/zerofrom/Cargo.toml

@@ -14,7 +14,7 @@ edition.workspace = true
 include.workspace = true
 license.workspace = true
 repository.workspace = true
-rust-version.workspace = true
+rust-version = "1.71.1"
 
 [package.metadata.workspaces]
 independent = true

utils/zerofrom/derive/Cargo.toml

@@ -13,6 +13,7 @@ keywords = ["zerocopy", "serialization", "lifetime", "borrow"]
 edition.workspace = true
 license.workspace = true
 repository.workspace = true
+rust-version = "1.71.1"
 
 [package.metadata.workspaces]
 independent = true
@@ -30,4 +31,3 @@ synstructure = { workspace = true }
 [dev-dependencies]
 zerofrom = { path = "..", features = ["derive"]}
 zerovec = { path = "../../../utils/zerovec", features = ["yoke"] }
-