bug#27178: 26.0.50; libxml-parse-*-region functions ignore discard-comments argument

[Sean McAfee <eefacm@gmail.com>]

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The libxml-parse-html-region and libxml-parse-xml-region functions both
appear to ignore their discard-comments parameters.

When I enter the following text in a buffer and mark it:

  <p>This <!-- and --> that</p>

Then the result of evaluating the expression

  (libxml-parse-html-region (mark) (point) nil t)

is

  (html nil (body nil (p nil "This " (comment nil " and ") " that")))

and the result of evaluating the expression

  (libxml-parse-xml-region (mark) (point) nil t)

is

  (p nil "This " (comment nil " and ") " that")

In both cases, I would expect that passing t as the fourth argument
would cause the comments to be dropped, but they are not.

Incidentally, I notice that the documentation for
libxml-parse-xml-region includes the following sentence:

  If DISCARD-COMMENTS is non-nil, all HTML comments are discarded.

I imagine this ought to refer to "XML comments" rather than "HTML
comments."


In GNU Emacs 26.0.50 (build 1, x86_64-apple-darwin13.4.0, NS appkit-1265.21
Version 10.9.5 (Build 13F1911))
 of 2017-05-15 built on builder10-9.local
Windowing system distributor 'Apple', version 10.3.1504
Recent messages:
(html nil (body nil (p nil "this " (comment nil " and ") " that"))) [2
times]
Auto-saving...
funcall-interactively: Beginning of buffer
(html nil (body nil (p nil "this " (comment nil " and ") " that"))) [2
times]
Quit [4 times]
Mark activated
(p nil "this " (comment nil " and ") " that")
uncompressing dom.el.gz...done
Note: standard-indent adjusted to 2
Quit [3 times]

Configured using:
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Load-path shadows:
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