test/coff — PE/COFF format roundtrip harness

Round-trip testing for emit_coff / read_coff against the x86_64-windows and aarch64-windows targets. Peer of test/elf/ and test/macho/.

Scope

Hand-built ObjBuilder → emit_coff → bytes → read_coff → second emit_coff against the readback. The harness asserts:

1. Structural equivalence between the original ObjBuilder and the readback (sections, symbols, relocations, groups all preserved modulo synthesized SECTION symbols and section-definition aux records — the asymmetry that src/obj/coff/read.c documents).
2. Byte stability across emit_coff(read_coff(emit_coff(ob))) — the second emit must produce the exact bytes of the first.

Running

make test-coff

This builds build/test/kit-roundtrip-coff and runs the embedded unit cases. It also runs windows-ucrt-hosted-smoke.sh, which self-skips unless an llvm-mingw UCRT sysroot is available via KIT_SYSROOT, under build/llvm-mingw/*/ucrt, or under /tmp/llvm-mingw*. Windows VM execution is optional; see doc/WINDOWS.md.

Layers

CORPUS.md enumerates the cases worth covering, marked:

• U (unit) — hand-built ObjBuilder fixtures. Layer A. The current harness only carries U cases.
• C (cases) — mingw-cross-built .obj fixtures. Layer B. The hosted UCRT smoke now covers one aarch64 llvm-mingw sysroot path; broader fixture coverage remains pending.
• E (exec) — link + exec via configured Windows VMs, with Wine as a fallback when available.

Layer A is sufficient to gate the wire encoder / decoder against each other. Layers B/C/D will catch cross-tool agreement and end-to-end runtime correctness once the surrounding infrastructure lands.

Pointer

See doc/WINDOWS.md for the UCRT sysroot provisioning and VM execution commands.