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bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp
From: |
Mattias Engdegård |
Subject: |
bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven |
Date: |
Mon, 7 Dec 2020 14:49:40 +0100 |
7 dec. 2020 kl. 11.41 skrev Filipp Gunbin <fgunbin@fastmail.fm>:
> It was me who put there those quantifiers, and I don't object to making
> the regexps stricter.
It would be unfair to blame you for that! After all, that's how most of the
other patterns were written, and for logical reasons: it seems intuitive and
sensible to make the rules as loose as possible in case the format changes or
there is otherwise a variation in the output. If the observed messages contain
a single space in one place then standard practice has been to tolerate any
number of spaces there, maybe even zero.
However, experience tells us that this intuition is wrong. Output formats do in
fact tend to remain unchanged: Emacs and other editors, IDEs and other code are
parsing them, and they are not all equally tolerant or in the same way. There
is thus a self-reinforcing effect: the tool keeps output stable because we
expect it to. (When output formats do change, it tends to be for good reasons
and regexp tolerance is then rarely useful.)
> But, we just need to be aware that Java tools usually don't expect the
> output to be parsed.
Yes they do! The very composition of something like the gradle-kotlin output
e: FILENAME: (LINE, COL): MESSAGE
is so strict and formalised that it was definitely made with
machine-readability in mind.
> That is why I'm more inclined to
> making regexps more _lax_, not the other way around (and fix the
> problems with them once they appear).
As we have found out the hard way, the cost of lax patterns is insidious and
diffuse until the mess really has to be sorted out -- and by then it's hard to
get hold of the various people involved who have since long disappeared or
forgot all about what they wrote years ago. Patterns are added independently of
one another but interact in unexpected ways.
Thus, better to keep patterns strict, and only alter them when and if tool
output changes; it is then clear exactly what needs to be done and why. For
most rules this never becomes necessary.
- bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven, Mattias Engdegård, 2020/12/04
- bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven, Filipp Gunbin, 2020/12/05
- bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven, Mattias Engdegård, 2020/12/06
- bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven, Filipp Gunbin, 2020/12/06
- bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven, Mattias Engdegård, 2020/12/06
- bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven, Mattias Engdegård, 2020/12/06
- bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven, Filipp Gunbin, 2020/12/07
- bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven,
Mattias Engdegård <=
- bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven, Filipp Gunbin, 2020/12/07
- bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven, Mattias Engdegård, 2020/12/09
- bug#18109: 24.4.50; `compilation-error-regexp-alist-alist': wrong regexp for Maven, Filipp Gunbin, 2020/12/10