Stdlib: error_log() — write message to SAPI/error log (ext/standard/basic_functions.c parity)

[PurHur]

Category

stdlib

Problem

error_log(string $message, int $message_type = 0, ?string $destination = null, ?string $additional_headers = null): bool is not registered in ext/standard/Module.php. Application and library code uses it for diagnostics when exceptions are not appropriate. function_exists('error_log') is false under bin/vm.php (verified May 2026).

php-src reference

• php/php-src ext/standard/basic_functions.c — PHP_FUNCTION(error_log)
• php/php-src main/SAPI.c — php_error_log() dispatch to syslog/file/SAPI

Repro (failure today)

<?php
if (!function_exists('error_log')) {
    fwrite(STDERR, "MISSING: error_log\n");
    exit(1);
}
error_log('hello from error_log');
echo "ok\n";

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php repro.php'
# exit 1 — function missing

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php -r "var_dump(function_exists(\"error_log\"));"'
# bool(true) on Zend; bool(false) on this compiler

Scope

Module	Path
Registration	ext/standard/Module.php
VM implementation	ext/standard/error_log.php (new)
JIT/AOT	ext/standard/JitErrorLog.php or host delegate
Tests	test/compliance/cases/stdlib/error_log.phpt
Matrix	script/capability-matrix.php

Done when

• error_log($msg) writes to stderr or SAPI log (type 0 subset matching Zend on CLI)
• Returns true on success, false on failure (invalid destination)
• VM + JIT + AOT rows green in docs/capabilities.md
• ./script/ci-fast.sh --filter error_log green

Notes

• Phase 1: message types 0 (SAPI) and 3 (file append) are enough for compiler/stdlib self-host; syslog (1) optional follow-up.
• Parent epic: Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 (stdlib parity supports bootstrap diagnostics).

[PurHur]

claim: PHP Compiler STD Lib — starting this run

[PurHur]

Merged via #8322.

Verification (green on branch):

• function_exists('error_log') → true on VM
• vendor/bin/phpunit --filter ErrorLogBuiltinTest → OK (5 tests)
• vendor/bin/phpunit --filter "stdlib/error_log" → OK (VM + JIT compliance)
• php bin/vm.php test/repro/maintainer-error_log.php → stderr log + file append OK
• php bin/compile.php -o /tmp/el_aot test/repro/error_log_aot_type3.php → AOT type-3 append OK
• php bin/jit.php test/repro/maintainer-error_log.php → JIT OK

Implementation: VmErrorLog + error_log.php (php-src _php_error_log); JIT stderr via StringErrorLog/__compiler_error_log, type 3 via JitFilePutContents.