[codex] ci: retry MSYS2 package installs on Windows

[uchebnick]

What changed

This moves Windows MSYS2 package installation out of msys2/setup-msys2 and into an explicit retrying step.

Root cause

The failing install-smoke (windows-arm64) job was not broken by the docs diff itself. It failed while msys2/setup-msys2 was downloading toolchain packages via pacman, with a mirror timeout on mingw-w64-clang-aarch64-zlib.

Fix

• stop using the built-in install: path in msys2/setup-msys2
• add scripts/install_msys2_package.sh
• retry pacman -S --needed installs for Windows benchmark, test, and install-smoke jobs

Validation

• bash -n scripts/install_msys2_package.sh
• ruby -e 'require "yaml"; YAML.load_file(".github/workflows/ci.yml")'

[Copilot]

Pull request overview

This PR improves Windows CI stability by moving MSYS2 package installation out of msys2/setup-msys2’s built-in install: option and into a custom retrying pacman install script, mitigating transient MSYS2 mirror timeouts (notably on Windows ARM64).

Changes:

• Add scripts/install_msys2_package.sh to install a single MSYS2 package with retries and backoff.
• Update .github/workflows/ci.yml to remove install: ${{ matrix.msys_pkg }} from msys2/setup-msys2 and instead call the new script for benchmark, test, and install-smoke Windows jobs.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
scripts/install_msys2_package.sh	New retry wrapper around pacman -S --needed for a single package.
.github/workflows/ci.yml	Switch Windows MSYS2 toolchain installation to an explicit retrying step.

---

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[Copilot]

attempts and base_delay are treated as integers (used with -le and arithmetic expansion), but they come from env vars and are not validated. If a non-numeric value is provided, the script will fail with a confusing shell error (e.g., “integer expression expected”). Consider validating both vars early (or coercing to defaults) and exiting with a clear message when they’re not positive integers.

Suggested change

	case "$attempts" in
	''|*[!0-9]*)
	echo "MSYS2_PACMAN_ATTEMPTS must be a positive integer, got: ${attempts}" >&2
	exit 1
	;;
	esac
	if [ "$attempts" -le 0 ]; then
	echo "MSYS2_PACMAN_ATTEMPTS must be a positive integer, got: ${attempts}" >&2
	exit 1
	fi
	case "$base_delay" in
	''|*[!0-9]*)
	echo "MSYS2_PACMAN_RETRY_DELAY_SECONDS must be a positive integer, got: ${base_delay}" >&2
	exit 1
	;;
	esac
	if [ "$base_delay" -le 0 ]; then
	echo "MSYS2_PACMAN_RETRY_DELAY_SECONDS must be a positive integer, got: ${base_delay}" >&2
	exit 1
	fi

[Copilot]

Using --overwrite '*' allows pacman to overwrite any conflicting files, which can mask real packaging/file-conflict issues and potentially leave the MSYS2 environment in an unexpected state. If overwrites are required, consider narrowing the overwrite glob to the known conflicting paths/files (or documenting why a blanket overwrite is safe/needed here).

Suggested change

	attempt=1
	while [ "$attempt" -le "$attempts" ]; do
	if pacman --noconfirm -S --needed --overwrite '*' "$pkg"; then
	overwrite_glob="${MSYS2_PACMAN_OVERWRITE:-}"
	pacman_args=(--noconfirm -S --needed)
	if [ -n "$overwrite_glob" ]; then
	pacman_args+=(--overwrite "$overwrite_glob")
	fi
	attempt=1
	while [ "$attempt" -le "$attempts" ]; do
	if pacman "${pacman_args[@]}" "$pkg"; then