[felipebalbi]

Summary

Follow up on the cross-platform CI coverage requested in #8.

• Run the existing formatting, build, Clippy, and test checks on Linux, macOS, and Windows, with matrix fail-fast disabled.
• Avoid passing Unix rpath flags to the Windows linker, eliminating MSVC's LNK4044 warning.
• Normalize the sysroot as a literal path rather than a regex, fixing the Windows UI-test harness panic.
• Use platform-specific snapshots for the two tests that inspect OS-dependent standard-library process internals, preserving the existing Linux expectations.

The three portability fixes are separate commits preceding the workflow change. Dependency-policy checks and PR-comment workflows remain Linux-only.

Validation

All existing check-job commands passed locally on Windows without warnings, using RUSTFLAGS="-D warnings", CARGO_INCREMENTAL=0, and CARGO_PROFILE_DEV_DEBUG=0:

• cargo fetch --locked
• cargo fmt --all --check
• cargo build --locked
• cargo build --locked --tests
• cargo clippy --locked
• cargo test --locked — 10 UI tests and 3 Cargo tests passed; other platforms' revisions were correctly ignored.

The updated check workflow also passes actionlint.

Windows snapshots were generated natively. macOS snapshots were generated by cross-target analysis for aarch64-apple-darwin on Windows; native macOS and Linux verification remains for CI. Linux snapshot contents are unchanged.

[Copilot]

🟢 Approval recommended

No active review issues are reported for the cross-platform CI and portability changes.

No open issues 🎉

What changed in this PR

This PR extends existing CI checks to Linux, macOS, and Windows, following up on #8. It adds portability fixes for linking and the UI-test harness, plus platform-specific expectations for tests that inspect standard-library process internals.

Changes:

• Run formatting, builds, Clippy, and tests across all three operating systems with matrix fail-fast disabled.
• Skip Unix rpath flags on Windows and normalize sysroot paths literally rather than as regular expressions.
• Add OS-specific test revisions and snapshots, preserving Linux expectations and documenting snapshot updates.

File	Description
tests/​ui/​large_std_process.rs	Selects OS-specific test revisions.
tests/​ui/​large_std_process.host_windows.stderr	Adds Windows process diagnostic expectations.
tests/​ui/​large_std_process.host_macos.stderr	Adds macOS process diagnostic expectations.
tests/​ui/​large_std_process.host_linux.stderr	Preserves existing Linux diagnostic expectations.
tests/​ui-cargo/​fail-blacklist/​Cargo.toml	Selects OS-specific Cargo test revisions.
tests/​ui-cargo/​fail-blacklist/​Cargo.host_windows.stderr	Adds Windows blacklist diagnostic expectations.
tests/​ui-cargo/​fail-blacklist/​Cargo.host_macos.stderr	Adds macOS blacklist diagnostic expectations.
tests/​ui-cargo/​fail-blacklist/​Cargo.host_linux.stderr	Preserves existing Linux blacklist expectations.
tests/​compile-test.rs	Uses literal sysroot normalization and enables Cargo test directives.
README.md	Documents platform-specific snapshot maintenance.
build.rs	Skips Unix rpath configuration on Windows.
.github/​workflows/​check.yml	Adds the three-OS check matrix with fail-fast disabled.

_{Review effort: Balanced}