Subject: bug#29263: 26.0.90; Regression in doc-string highlighting

From: Drew Adams <[email-masked]>
Date: Sat, 11 Nov 2017 13:57:33 -0800 (PST)

(defun foo ()
  "Why does this show highlighting \* \( \) ??"
  nil)

Starting with Emacs 26 this highlights the backslashes differently from
the rest of the doc string (using face `font-lock-warning-face').

This is totally inappropriate.  Emacs is trying to be too clever here.
A backslash before `*' or a paren can mean any number of different
things in a doc string.

Consider this bit of a doc string, for instance:

 When both optional args are non-nil, the `find' command run is this:

   find . -mindepth MIN-DEPTH -maxdepth MAX-DEPTH
          \\( -path \*edir1\* -o -path \*edir2\* ... \\)
          -prune -o \\( ARGS \\) LS-SWITCHES"

It makes zero sense for `\*' here to have its backslash highlighted.
That just spreads confusion.  Any number of other examples can be
imagined.  A doc string is, above all, arbitrary natural-language text.
Trying to impose some clever semantics on backslashes is misguided.

Please revert this regressive behavior.

In GNU Emacs 26.0.90 (build 3, x86_64-w64-mingw32)
 of 2017-10-13 built on LAPHROAIG
Repository revision: 906224eba147bdfc0514090064e8e8f53160f1d4
Windowing system distributor 'Microsoft Corp.', version 6.1.7601
Recent messages:
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Char: \ (92, #o134, #x5c) point=142 of 41521 (0%) column=35

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