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Regression: session_start() after output — ignores headers-sent guard (ext/session/session.c) #17707
Description
Category
Regression · php-src-strict
Problem
After any output has been sent (headers effectively started), Zend session_start() emits a warning, returns false, and leaves session_status() at PHP_SESSION_NONE (1). This compiler starts the session anyway (true, status 2).
| Repro | Zend 8.2+ | VM (2026-07-10) |
|---|---|---|
echo "x"; session_start(); return value |
false + Warning |
true (no warning) |
session_status() after failed start |
1 |
2 |
php-src reference
- php/php-src
ext/session/session.c—php_session_start()refuses whenSG(headers_sent)
PHP implementation target
ext/standard/session_start.php— consultheaders_sent()/VmSapiHeaderGuardbeforeVmSession::start()ext/standard/VmSession.php— shared guard for JIT/AOT viaJitSessionStart/__phpc_session_start_apply
Repro
./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_session_start_headers_sent.php'Done when
- VM/JIT/AOT match Zend warning text,
falsereturn, andsession_status()===PHP_SESSION_NONE - Compliance
.phptguard undertest/compliance/cases/session/ - php-src-strict; no php-compiler-strict shortcut
Activity
PurHur commentedon Jul 10, 2026
claim: PHP Compiler STD Lib Advanced — batch (issues #17708, #17707, #17709)
PurHur commentedon Jul 10, 2026
Merged in PR #17728 — VM repro + compliance guards green. See PR body for verification transcript.
Stdlib: session headers guard, iconv incomplete notice, password TYPE…
PurHur commentedon Jul 15, 2026
claim: PHP Compiler Ext — I/O & Crypto — starting this run (session PHPT fixtures stale after #17707 headers-sent guard; 14 VMTest session failures on PHP_COMPILER_PROFILE=8.4).
PurHur commentedon Jul 15, 2026
Merged via PR #19226.
Shipped:
session_id('')clears internal id (VM + JIT) — php-src parityob_start()/ reorder / expect refresh)session_regenerate_idexpect sid length 26 (PHP 8.2+ default)Verification:
Session: fix session_id('') clear + PHPT headers-sent guards (#17707) (…