Bug 285807 – RegExp with lookbehind returns fewer matches in Safari than Chrome (?<=(?:do\(\)|^)(?:[^d]|d(?!on't\(\)))*)mul\((\d{1,3}),(\d{1,3})\)/

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Jarred Sumner]

Reproduction:
```
const str = `
mul(1,2)select()don't()select()select()}<-when()?}mul(601,494)mul(184,68)mul(703,694)&;;!}![mul(255,743)who()* ^select()%mul(772,315)what()-mul(799,280):who()why();!what()]+what()how(847,982)mul(276,198);select()<*;>:,@mul(293,345)/)what()%!what()<~mul(959,852)/+$why()^<!-mul(756,324)how()>why()where(),@mul(281,314)#when()%]! -mul(347{why()select()why():)^~mul(10,106)%+?%when()mul(941,657)select()when()&,@@'@mul(250,253)#,what()mul(539,823);^*<[mul(422,155)who(){$:-&#mul:mul(61,174):why()'where()don't()select()<&+!/@&<-mul(596,236)~mul(339,838)'}mul(263,931)!how()mul(65,701)from()'/>/)mul(879,804)how() {*((mul(213,689)*[when()}what()?where())mul(727,958)mul(246,840)+mul(150,479)>?~from()*mul(552,678)?don't()$~?'mul(97,380)>mul(968,76)}#!from()mul(435,362why()#}when()*[how()'!#mul(357,345)}?why()[[mul(356,875)%when())$#mul{from()mul(289,657)from(681,624)'<;who()mul(514,298);{ mul-/[(:who():mul(789,109)where()%}what(435,852)mul(330,192)why();)$-]+mul(617,542)mul(244,889)?*%'>!mul(799,990)from()(mul(234,708)
@; ;?&]?#mul(577,752)%*)$&why()!%[mul(7,487)how(),@]select()$mul(38-?-+:^[from()#mul(252,810)who()]<+<who()how()]mul(85{$+who()mul(30,63)~who(743,434)~;mul(808,964)~?mul(459,384)>!)mul(976,357)[}mul(341,264)/#select(),%select()&mul(547,552)where()from()@+}#:mul(592,61)&how()what();select()!^select()(mul(273,4)'/^mul(446,170)%]]'~+mul(678,454)when()}select())/?#+}mul(180,876)-%%why()mul(255,652)]why()$#!mul(114,812)-?mul(207,511)<who()<>[$how()+}^mul(790,315)%who()/&<mul(631,708)+%+mul(674,272)when(792,225)&~how()}+how()mul(342 /where()how()who(){<{~mul(848,950)>]do()]#@why()/mul(743,708)
`;

const regex = /(?<=(?:do\(\)|^)(?:[^d]|d(?!on't\(\)))*)mul\((\d{1,3}),(\d{1,3})\)/g;

const matches = str.matchAll(regex);
const matchesArr = [...matches];

globalThis.console ??= { log: (args) => print(JSON.stringify(args, null, 2)) };
console.log(matchesArr.map(match => match[0]));
```

Chrome & Node.js:
```
[ 'mul(1,2)', 'mul(743,708)' ]
```

Safari Technology Preview, jsc shell, and Bun:
```
["mul(1,2)"]
```

From https://github.com/oven-sh/bun/issues/16338

[Radar WebKit Bug Importer]

<rdar://problem/143202375>

Pull request: https://github.com/WebKit/WebKit/pull/39357

[EWS]

Committed 289319@main (d30962803be5): <https://commits.webkit.org/289319@main>

Reviewed commits have been landed. Closing PR #39357 and removing active labels.