AOT: mb_detect_encoding() refuses runtime strings — LogicException 1-arg NestedJIT (leftover of #3075, ext/mbstring/mbstring.c)

[PurHur]

Category

bug · AOT NestedJIT · leftover of #3075 / peer #34338 mb_scrub · Pillar Correctness

Problem

mb_detect_encoding() JIT only compile-time-folds the 1-arg literal form. A runtime haystack (chr(0xE2).chr(0x82).chr(0xAC)) or any encodings-list argument throws:

mb_detect_encoding() JIT requires a compile-time string literal (1-arg) in this compiler build

VM/Zend return UTF-8 / ASCII. Same leftover shape as #34338 / #34309 (NestedJIT helper, no VmMbstring from thin AOT).

Verified on master @ b3cbdaf036 (aot-smoke 8/8):

Repro	Zend 8.2 / VM	AOT thin
$s=chr(0xE2).chr(0x82).chr(0xAC); echo mb_detect_encoding($s);	UTF-8	LogicException (compile rc=2)
echo mb_detect_encoding('café', ['UTF-8','ASCII'], true);	UTF-8	same LogicException
echo mb_detect_encoding('hello'); (literal)	ASCII	ASCII (fold)

php-src reference

• php/php-src ext/mbstring/mbstring.c — PHP_FUNCTION(mb_detect_encoding)

PHP implementation target

• ext/mbstring/JitMbDetectEncoding.php — NestedJIT for runtime $string; encodings list + $strict remain compile-time (peer JitMbScrub)
• ext/mbstring/MbDetectEncodingJitHelper.php — ASCII / UTF-8 / ISO-8859-1 / 8BIT leaf; no VmMbstring / MbstringState (NestedJIT abort)
• lib/JIT/Builtin/MbDetectEncodingRuntime.php — lazy JitVmHelperLink (not Type::initialize)

Repro

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php bin/vm.php test/repro/aot_mb_detect_encoding_runtime.php
php bin/compile.php -o /tmp/det.bin test/repro/aot_mb_detect_encoding_runtime.php && /tmp/det.bin'

Done when

• AOT matches Zend/VM for runtime 1-arg and literal encodings-list (+ strict)
• Unit + repro green; ./script/aot-smoke.sh still 8/8
• php-src-strict; no php-compiler-strict shortcut; no new runtime/*.c

Related

• Stdlib: mb_convert_encoding / mb_detect_encoding (ext/mbstring parity) #3075 (original detect/convert)
• AOT: mb_scrub() refuses runtime strings — LogicException (leftover of #6050, ext/mbstring/mbstring.c) #34338 mb_scrub NestedJIT leftover pattern
• AOT: mb_convert_encoding() refuses runtime strings — LogicException (leftover of #6251, ext/mbstring/mbstring.c) #34309 mb_convert_encoding NestedJIT leftover pattern

[PurHur]

Claiming — NestedJIT MbDetectEncodingJitHelper (peer #34338), no VmMbstring.

[PurHur]

claim: stdlib+AOT agent run 2026-08-24T06:23Z

[PurHur]

claim: worker-lane-c — lane overflow (#34358 only open AOT crash; prior claim has no PR)