Minimal-versions check skipped in CI since #452, and it fails on `serde` 1.0.60

[glaziermag]

The last block of ci/test-stable.sh (cargo check --benches and the minimal-versions check) has not run in CI since #452. It is gated on RUST_VERSION:

bytes/ci/test-stable.sh

Lines 14 to 25 in 7930d93

	if [[ "${RUST_VERSION}" == "nightly"* ]]; then
	# Check benchmarks
	cargo check --benches
	# Check minimal versions
	# Remove dev-dependencies from Cargo.toml to prevent the next `cargo update`
	# from determining minimal versions based on dev-dependencies.
	cargo hack --remove-dev-deps --workspace
	# Update Cargo.lock to minimal version dependencies.
	cargo update -Z minimal-versions
	cargo check --all-features
	fi

#452 removed RUST_VERSION: nightly-2019-09-25 from the nightly job in favour of the workflow-level nightly variable, and nothing sets RUST_VERSION now (grep -rn RUST_VERSION .github ci finds only line 14). The job still passes because the block is skipped. In the 2026-09-06 scheduled run (job log), set -x shows the all-features tests followed directly by an empty comparison, and then the job ends:

+ cargo test --all-features
...
+ [[ '' == \n\i\g\h\t\l\y* ]]

With the condition fixed on a fork, cargo check --benches passes, but the minimal-versions check fails. cargo update -Z minimal-versions selects serde 1.0.60, the floor in Cargo.toml, and it does not compile with the alloc feature on the CI nightly (fork job log):

 Downgrading serde v1.0.229 -> v1.0.60 (latest compatible: v1.0.229)
...
error[E0432]: unresolved imports `alloc::BTreeMap`, `alloc::BTreeSet`, `alloc::BinaryHeap`, `alloc::LinkedList`, `alloc::VecDeque`
   --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/serde-1.0.60/src/lib.rs:192:21
...
error: could not compile `serde` (lib) due to 1 previous error

So fixing the condition alone would turn nightly red, and skip publish_docs, which needs it, unless the serde requirement changes too. #797 would change it to serde_core 1.0.220; I have not run the check with that change. Cargo stopped at this first error, so bytes itself was not checked against the minimal versions.

The condition change I used on the fork:

-if [[ "${RUST_VERSION}" == "nightly"* ]]; then
+if [[ "$(rustc --version)" == *nightly* ]]; then

Fork runs on glaziermag/bytes run the full CI workflow; the baseline adds only a workflow_dispatch trigger. Baseline nightly job: green, block skipped. With the change: red at the serde floor.

I found this while auditing the CI jobs, read the job logs through the Actions API, and ran the fork builds linked above. I used AI assistance (Claude) for the investigation and drafting.