Problems with `@anchor` and `@xrefautomaticsectiontitle`

[Werner LEMBERG]

[texinfo 2020-11-25.18]
[pdftex TeXLive 2020]


This example

  \input texinfo.tex

  @xrefautomaticsectiontitle on

  @node foo_bar
  @subsection Foo_Bar

  @page

  @anchor{blubb}
  Blubb

  @page

  @xref{blubb}

  @bye

exhibits a bug and a problem if converted to PDF, as can be seen in
the attached image.

The bug:
  The `_` character in the section title is displayed as a dot accent
  in the PDF output of the anchor reference.

The problem:
  In the anchor reference the corresponding section reference title is
  shown.  IMHO, this doesn't make much sense because it loses context
  – in the example above, how shall the reader know that she has to
  look for 'blubb'?  A better solution is to use the anchor node name
  if #3 of `@xref` is missing, inspite of `@xrefautomaticsectiontitle
  on`.

  Note that for automatically generated `@xref` entries (as we have in
  LilyPond's 'Internal Reference' manual) it is not possible to
  manually provide a third argument; it would be thus quite valuable
  if the default could be improved.


    Werner