master 24a9875 1/2: Remove outdated documentation from cperl-mode.el

[Stefan Kangas]

branch: master
commit 24a98755ab7dd6b0805da02d040c9eb3bf5feac9
Author: Stefan Kangas <stefan@marxist.se>
Commit: Stefan Kangas <stefan@marxist.se>

    Remove outdated documentation from cperl-mode.el
    
    * lisp/progmodes/cperl-mode.el (cperl-tips, cperl-problems)
    (cperl-praise, cperl-speed, cperl-mode): Doc fixes; remove references
    to very old versions of Emacs and other "Emaxen".
    (cperl-problems-old-emaxen): Make obsolete and remove information on
    Emacs 20.3 and older.
---
 lisp/progmodes/cperl-mode.el | 69 ++++++++------------------------------------
 1 file changed, 12 insertions(+), 57 deletions(-)

diff --git a/lisp/progmodes/cperl-mode.el b/lisp/progmodes/cperl-mode.el
index 97d0e36..167b2c6 100644
--- a/lisp/progmodes/cperl-mode.el
+++ b/lisp/progmodes/cperl-mode.el
@@ -659,8 +659,8 @@ Run Perl/Tools/Insert-spaces-if-needed to fix your lazy 
typing.
 
 Switch auto-help on/off with Perl/Tools/Auto-help.
 
-Though with contemporary Emaxen CPerl mode should maintain the correct
-parsing of Perl even when editing, sometimes it may be lost.  Fix this by
+Though CPerl mode should maintain the correct parsing of Perl even when
+editing, sometimes it may be lost.  Fix this by
 
   \\[normal-mode]
 
@@ -676,63 +676,20 @@ micro-docs on what I know about CPerl problems.")
   "Description of problems in CPerl mode.
 `fill-paragraph' on a comment may leave the point behind the
 paragraph.  It also triggers a bug in some versions of Emacs (CPerl tries
-to detect it and bulk out).
-
-See documentation of a variable `cperl-problems-old-emaxen' for the
-problems which disappear if you upgrade Emacs to a reasonably new
-version (20.3 for Emacs).")
+to detect it and bulk out).")
 
 (defvar cperl-problems-old-emaxen 'please-ignore-this-line
-  "Description of problems in CPerl mode specific for older Emacs versions.
-
-Emacs had a _very_ restricted syntax parsing engine until version
-20.1.  Most problems below are corrected starting from this version of
-Emacs, and all of them should be fixed in version 20.3.  (Or apply
-patches to Emacs 19.33/34 - see tips.)
-
-Note that even with newer Emacsen in some very rare cases the details
-of interaction of `font-lock' and syntaxification may be not cleaned
-up yet.  You may get slightly different colors basing on the order of
-fontification and syntaxification.  Say, the initial faces is correct,
-but editing the buffer breaks this.
-
-Even with older Emacsen CPerl mode tries to corrects some Emacs
-misunderstandings, however, for efficiency reasons the degree of
-correction is different for different operations.  The partially
-corrected problems are: POD sections, here-documents, regexps.  The
-operations are: highlighting, indentation, electric keywords, electric
-braces.
-
-This may be confusing, since the regexp s#//#/#; may be highlighted
-as a comment, but it will be recognized as a regexp by the indentation
-code.  Or the opposite case, when a POD section is highlighted, but
-may break the indentation of the following code (though indentation
-should work if the balance of delimiters is not broken by POD).
-
-The main trick (to make $ a \"backslash\") makes constructions like
-${aaa} look like unbalanced braces.  The only trick I can think of is
-to insert it as $ {aaa} (valid in perl5, not in perl4).
-
-Similar problems arise in regexps, when /(\\s|$)/ should be rewritten
-as /($|\\s)/.  Note that such a transposition is not always possible.
-
-The solution is to upgrade your Emacs or patch an older one.  Note
-that Emacs 20.2 has some bugs related to `syntax-table' text
-properties.  Patches are available on the main CPerl download site,
-and on CPAN.
-
-If these bugs cannot be fixed on your machine (say, you have an inferior
-environment and cannot recompile), you may still disable all the fancy stuff
-via `cperl-use-syntax-table-text-property'.")
+  "This used to contain a description of problems in CPerl mode
+specific for very old Emacs versions.  This is no longer relevant
+and has been removed.")
+(make-obsolete-variable 'cperl-problems-old-emaxen nil "28.1")
 
 (defvar cperl-praise 'please-ignore-this-line
   "Advantages of CPerl mode.
 
 0) It uses the newest `syntax-table' property ;-);
 
-1) It does 99% of Perl syntax correct (as opposed to 80-90% in Perl
-mode - but the latter number may have improved too in last years) even
-with old Emaxen which do not support `syntax-table' property.
+1) It does 99% of Perl syntax correct.
 
 When using `syntax-table' property for syntax assist hints, it should
 handle 99.995% of lines correct - or somesuch.  It automatically
@@ -813,8 +770,7 @@ the settings present before the switch.
 9) When doing indentation of control constructs, may correct
 line-breaks/spacing between elements of the construct.
 
-10) Uses a linear-time algorithm for indentation of regions (on Emaxen with
-capable syntax engines).
+10) Uses a linear-time algorithm for indentation of regions.
 
 11) Syntax-highlight, indentation, sexp-recognition inside regular expressions.
 ")
@@ -838,8 +794,8 @@ syntax-parsing routines, and marks them up so that either
 
     A1) CPerl may work around these deficiencies (for big chunks, mostly
         PODs and HERE-documents), or
-    A2) On capable Emaxen CPerl will use improved syntax-handling
-       which reads mark-up hints directly.
+    A2) CPerl will use improved syntax-handling which reads mark-up
+        hints directly.
 
     The scan in case A2 is much more comprehensive, thus may be slower.
 
@@ -1514,8 +1470,7 @@ span the needed amount of lines.
 
 Variables `cperl-pod-here-scan', `cperl-pod-here-fontify',
 `cperl-pod-face', `cperl-pod-head-face' control processing of POD and
-here-docs sections.  With capable Emaxen results of scan are used
-for indentation too, otherwise they are used for highlighting only.
+here-docs sections.  Results of scan are used for indentation too.
 
 Variables controlling indentation style:
  `cperl-tab-always-indent'