Self-host M3: inventory driver phantom emit guard — require non-empty -o always

[PurHur]

Category

bootstrap

Problem

The bootstrap inventory argv driver (bin/compile.php / native AOT driver invoked from script/bootstrap-inventory.php) can exit 0 after printing a compile-OK line while never writing the -o output file (or writing zero bytes). bootstrap_inventory_argv_emit_output_ok in the bootstrap scripts guards this (#3046), but the compiler should fail loudly itself so gen-0 / M3 gates cannot pass on phantom emits.

This blocks trustworthy M3 native compile verification and hides linker/driver bugs.

php-src reference

• N/A (compiler bootstrap). Analogous to php-src build tools failing when -o is missing after successful compile.

Repro

# After implementing the guard, this synthetic failure mode must non-zero:
# (exact trigger depends on current driver — reproduce via bootstrap inventory emit step)

BOOTSTRAP_INVENTORY_EMIT=1 php script/bootstrap-inventory.php --emit-only 2>&1 | tee /tmp/inv-emit.log
test -s /tmp/bootstrap-inventory-driver.out || echo "MISSING OUTPUT"

# Stricter: force driver with -o pointing at unwritable path / dev-null discard and assert non-zero
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && make bootstrap-selfhost-inventory-emit-probe'

Today: driver may return success without a non-empty -o artifact; outer script catches some cases but not all native paths.

Scope (this repo)

• bin/compile.php — post-compile stat on -o path (size > 0, regular file)
• lib/AOT/ native driver emit path (shared helper with bin/compile.php)
• script/bootstrap-inventory.php — tighten bootstrap_inventory_argv_emit_output_ok messages; keep as belt-and-suspenders
• Tests: test/unit/BootstrapInventoryEmitTest.php — temp -o missing/empty → non-zero exit

Done when

• Native + Zend fallback drivers return non-zero and stderr diagnostic when -o missing, empty, or not created after successful compile line
• BOOTSTRAP_INVENTORY_EMIT=1 probe in make north-star5-verify-fast cannot pass with phantom emit
• ./script/ci-fast.sh --filter BootstrapInventoryEmit green
• No new C runtime logic — PHP driver checks only

Verify

make bootstrap-selfhost-vm-driver-execute-probe
make north-star5-verify-fast
./script/ci-fast.sh --filter BootstrapInventoryEmit

Links

• Self-host M5: bootstrap-compile-invoke treats exit-0 driver run without output as failure (stale sync-back artifact) #3046 (original phantom emit guard), Self-host M3: native Compiler::compile on inventory argv driver path #8708 (native compile path), Self-host M4: gen-3 full-revision without prelinked gen-0 sidecar copy #8710 (inventory driver size floor)
• North star: Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 · ROADMAP 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78

[PurHur]

claim: cursor-agent-lane-a — starting this run

[PurHur]

Merged via #8840

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php vendor/bin/phpunit --filter BootstrapInventoryEmitTest'
# OK (6 tests, 10 assertions)

Changes

• PHPCompiler\AOT\Linker::{assertNonEmptyOutputFile,assertNonEmptyRequestedOutput} — shared post-emit guard (Self-host M5: bootstrap-compile-invoke treats exit-0 driver run without output as failure (stale sync-back artifact) #3046, Self-host M3: inventory driver phantom emit guard — require non-empty -o always #8709)
• lib/JIT/Context::compileToFile() — enforce non-empty object/executable after emit+link
• bin/compile.php — non-zero exit when -o missing/empty after standalone()
• bootstrap_inventory_argv_emit_output_ok — explicit stderr diagnostics for missing/non-executable/empty -o