Phase 11. Cross-compile tier-1 matrix
| Field | Value |
|---|---|
| MEP | MEP-45 §Phases · Phase 11 |
| Status | LANDED |
| Started | 2026-05-25 23:00 (GMT+7) |
| Landed | 2026-05-26 00:01 (GMT+7) |
| Tracking issue | — |
| Tracking PR | — |
Gate
Every Phase 1-10 fixture compiles via mochi build --target=<triple> from every supported host and runs byte-equal vs vm3 on the target (native on macOS+Linux, qemu-user-static for cross-arch Linux, wasmtime for wasi).
Goal-alignment audit
Tier-1 cross is the user-facing payoff of MEP-45: one source, every native target, without installing a separate toolchain. The zig cc path means users only need mochi build --triple=<target> and the runtime downloads zig automatically. Aligns directly with user-facing goal.
Sub-phases (one per target)
| # | Target | Status | Commit | PR |
|---|---|---|---|---|
| 11.0 | x86_64-linux-gnu (native) | LANDED 2026-05-25 23:00 (GMT+7) | — | — |
| 11.1 | x86_64-linux-musl (zig cc) | LANDED 2026-05-25 23:00 (GMT+7) | — | — |
| 11.2 | aarch64-linux-gnu (zig + qemu) | LANDED 2026-05-25 23:00 (GMT+7) | — | — |
| 11.3 | aarch64-linux-musl (zig + qemu) | LANDED 2026-05-25 23:00 (GMT+7) | — | — |
| 11.4 | aarch64-darwin (native macOS) | LANDED 2026-05-25 23:00 (GMT+7) | — | — |
| 11.5 | x86_64-darwin (zig cc cross) | LANDED 2026-05-25 23:59 (GMT+7) | — | — |
| 11.6 | x86_64-windows-msvc (clang-cl) | LANDED 2026-05-26 00:01 (GMT+7) | — | — |
| 11.7 | x86_64-windows-gnu (zig+mingw) | LANDED 2026-05-26 00:01 (GMT+7) | — | — |
Deliverables
.github/workflows/transpiler3-c-cross-tier1.yml extends cross-aot.yml's pattern: Linux CI runner covers 11.0-11.3 (native + zig cc + qemu); macOS CI runner covers 11.4 (native aarch64-darwin).
Decisions made
resolveCCForTarget in driver. Phase 11 adds resolveCCForTarget(target string) to Driver. When target != "" and no explicit CC is set, it calls zig.Install() to get the bundled zig binary and uses zig cc as the compiler. This matches the MEP-42 pattern in compiler3/build/c/driver.go:resolveCC. The -target=<triple> flag is then prepended to ccArgs before the standard compile flags.
NoZigFallback skip for cross. If Driver.NoZigFallback is true and target != "", the cross-compile path still falls back to resolveCC (host discovery) rather than downloading zig. This preserves the existing test contract that NoZigFallback prevents network access.
MOCHI_TEST_ZIG_DOWNLOAD=1 opt-in. Cross tests that require zig (11.1-11.3) skip unless MOCHI_TEST_ZIG_DOWNLOAD=1 is set, preventing accidental network access in the default go test run. The CI workflow sets this env var unconditionally.
Native gates (11.0, 11.4) are unconditional. TestPhase11NativeLinux and TestPhase11NativeDarwin use the host cc and never download zig, so they do not need the opt-in guard.
qemu-based run gates. Tests for aarch64 targets check for qemu-aarch64-static or qemu-aarch64 on PATH. If neither is found, the test is compile-only (verifies the binary is produced without running it). The CI workflow installs qemu-user-static via apt before these tests run.
Phase 11.5 decisions
zig cc cross with -target=x86_64-macos-none. On macOS arm64, zig cc produces an x86_64 Mach-O binary. Rosetta 2 is always present on Apple Silicon CI runners (GitHub Actions macos-latest), so the binary runs transparently via exec.Command(bin) without any arch wrapper.
Two CI jobs for 11.5. cross-macos (arm64, macos-latest) adds a Phase 11.5 step with MOCHI_TEST_ZIG_DOWNLOAD=1 that runs TestPhase11X86DarwinCross. A new cross-macos-x86 job on macos-13 (x86_64) reuses TestPhase11NativeDarwin (triple="") for the native x86_64 run gate without zig.
TestPhase11X86DarwinCross skips on non-arm64 macOS. On x86_64 macOS the native path already covers the run gate, so the cross test gates on runtime.GOARCH == "arm64" to avoid double-running.
Phase 11.6/11.7 decisions
TestPhase11NativeWindows (Phase 11.6). Builds with an empty triple (host cc discovery) on windows-latest. GitHub Actions Windows runners ship clang-cl and Visual C++ Build Tools, so host cc resolves to cl.exe or clang-cl.exe. Output is named .exe so it runs directly.
TestPhase11WindowsGnu (Phase 11.7). Uses x86_64-windows-gnu triple via zig cc. The resulting PE binary is a MinGW-ABI executable; on the Windows runner it runs natively. On non-Windows hosts the test is compile-only (no run gate).
Windows CI job uses backtick line continuation. PowerShell requires ` instead of \ for multi-line commands; the cross-windows job uses that convention.
MOCHI_TEST_ZIG_DOWNLOAD=1 set at the Windows job level. Both Phase 11.6 and 11.7 steps share the opt-in since both may trigger zig download on Windows (Phase 11.7 definitely does; Phase 11.6 uses host cc but zig fallback is still allowed).
Deferred work
- Tier-2 (BSDs, riscv64, armv7, aarch64-windows): behind a
--tier=2flag.
Closeout notes
All 8 Phase 11 sub-phases (11.0-11.7) are LANDED.