bug#28329: 25.2; Eshell: 40M+ output: Stack overflow in regexp matcher

[Noam Postavsky <npostavs@users.sourceforge.net>]

> From: Pierre Neidhardt <pe.neidhardt@googlemail.com>
> Subject: Re: bug#28329: 25.2; Eshell: 40M+ output: Stack overflow in regexp matcher
> To: npostavs@users.sourceforge.net
> Date: Sat, 02 Sep 2017 19:02:21 +0100 (3 weeks, 18 hours, 25 minutes ago)
>
> Alright, I managed to get a stack trace:
>
> Debugger entered--Lisp error: (error "Stack overflow in regexp matcher")
>   re-search-forward("\\(\\(?:adgangskode\\|contrase\\(?:\\(?:ny\\|ñ\\)a\\)\\|geslo\\|h\\(?:\\(?:asł\\|esl\\)o\\)\\|iphasiwedi\\|jelszó\\|l\\(?:ozinka\\|ösenord\\)\\|m\\(?:ot
> de passe\\|ật khẩu\\)\\|pa\\(?:rola\\|s\\(?:ahitza\\|s\\(?:
> phrase\\|code\\|ord\\|phrase\\|wor[dt]\\)\\|vorto\\)\\)\\|s\\(?:alasana\\|enha\\|laptažodis\\)\\|wachtwoord\\|лозинка\\|пароль\\|ססמה\\|كلمة
> السر\\|गुप्तशब्द\\|शब्दकूट\\|গুপ্তশব্দ\\|পাসওয়ার্ড\\|ਪਾਸਵਰਡ\\|પાસવર્ડ\\|ପ୍ରବେଶ
> ସଙ୍କେତ\\|கடவுச்சொல்\\|సంకేతపదము\\|ಗುಪ್ತಪದ\\|അടയാളവാക്ക്\\|රහස්පදය\\|ពាក្យសម្ងាត់\\|
> パスワード\\|密[码碼]\\|암호\\)\\).*:\\s *\\'" #<marker at 20572261 in
> *eshell*> t)
>   eshell-watch-for-password-prompt()
>   run-hooks(eshell-output-filter-functions)
>   eshell-run-output-filters()
>   eshell-output-filter(#<process emerge>
> "ium/third_party/WebKit/Source/platform/network/blink_platform.WebSocketHandshakeRequest.o
> obj/src/3rdparty/chromium/third_party/WebKit/Source/platform/network/blink_platform.WebSocketHandshakeResponse.o
[...]
> ob")
>
> Apparently, the line is just plain too long...
> I guess limiting the regexp matcher over, say, the first 256 characters
> would fix the issue.
> ----------

Can you catch that build output in a file, so it could be reproduced by
running 'cat build.log' in eshell?  I tried copying the fragment you
have in your backtrace a couple of times to make it longer, but I was
unable to trigger the error.  Perhaps the particular contents of the
string matters too (some values might let the matcher short-circuit the
backtracking).