From 737ea7a32d336a0bf6b49fe542c87f4d2146a511 Mon Sep 17 00:00:00 2001
From: Steve Hancock <perltidy@users.sourceforge.net>
Date: Wed, 13 Jan 2021 20:30:02 -0800
Subject: [PATCH] Fix error in guessing if divide or pattern

---
 lib/Perl/Tidy/Formatter.pm | 22 +++++++++++++--
 local-docs/BugLog.pod      | 56 ++++++++++++++++++++++++++++++++++++--
 2 files changed, 73 insertions(+), 5 deletions(-)

diff --git a/lib/Perl/Tidy/Formatter.pm b/lib/Perl/Tidy/Formatter.pm
index 256ccd84..a5339bfd 100644
--- a/lib/Perl/Tidy/Formatter.pm
+++ b/lib/Perl/Tidy/Formatter.pm
@@ -6687,6 +6687,11 @@ sub weld_nested_containers {
         # two semi-stable states, if we do not weld.  So the rules for
         # not welding have to be carefully defined and tested.
         my $do_not_weld;
+
+        my $is_one_line_weld;
+
+        my $iline_oc = $outer_closing->[_LINE_INDEX_];
+
         if ( !$touch_previous_pair ) {
 
             # If this pair is not adjacent to the previous pair (skipped or
@@ -6704,6 +6709,20 @@ sub weld_nested_containers {
                   $ci_level * $rOpts_continuation_indentation;
             }
 
+            # An existing one-line weld is a line in which
+            # (1) the containers are all on one line, and
+            # (2) the line does not exceed the allowable length, and
+            # (3) there are no good line breaks (comma or semicolon).
+            # This flag is used to avoid creating blinkers.
+            if ( $iline_oo == $iline_oc && $excess_length_to_K->($Klast) <= 0 )
+            {
+                my $rtype_count =
+                  $self->[_rtype_count_by_seqno_]->{$inner_seqno};
+                $is_one_line_weld = 1
+                  unless ( $rtype_count
+                    && ( $rtype_count->{','} || $rtype_count->{';'} ) );
+            }
+
             # DO-NOT-WELD RULE 1:
             # Do not weld something that looks like the start of a two-line
             # function call, like this: <<snippets/wn6.in>>
@@ -6727,7 +6746,6 @@ sub weld_nested_containers {
             # $top_label->set_text( gettext(
             #    "Unable to create personal directory - check permissions.") );
 
-            my $iline_oc = $outer_closing->[_LINE_INDEX_];
             my $token_oo = $outer_opening->[_TOKEN_];
             if (   $iline_oc == $iline_oo + 1
                 && $iline_io == $iline_ic
@@ -6775,7 +6793,7 @@ sub weld_nested_containers {
         #    $_[0]->();
         # } );
 
-        if ( $iline_ic == $iline_io ) {
+        if ( !$is_one_line_weld && $iline_ic == $iline_io ) {
 
             my $token_oo = $outer_opening->[_TOKEN_];
             $do_not_weld ||= $token_oo eq '(';
diff --git a/local-docs/BugLog.pod b/local-docs/BugLog.pod
index 3fa7aca5..adacec39 100644
--- a/local-docs/BugLog.pod
+++ b/local-docs/BugLog.pod
@@ -2,6 +2,57 @@
 
 =over 4
 
+=item B<Fixed blinker related to large -ci, short line length and -wn>
+
+In random testing with convergence a 'blinker' (oscillating states) was found
+for the following script
+
+    sub _prompt {
+
+          print $_[0];
+          return (
+                readline
+                       (*{$_[1]})!~
+                       /^q/i)
+                 ; # Return false if user types 'q'
+
+    }
+
+with the following specific parameters:
+
+    --maximum-line-length=32
+    --indent-columns=6
+    --continuation-indentation=7
+    --weld-nested-containers
+    --extended-continuation-indentation
+    --noadd-whitespace
+
+The other state was
+
+    sub _prompt {
+
+          print $_[0];
+          return (
+                readline(
+                      *{
+                            $_
+                                   [
+                                   1
+                                   ]
+                      }
+                )!~/^q/i
+                 )
+                 ; # Return false if user types 'q'
+
+    }
+
+All of the listed parameters are required to cause this, but the main cause
+is the very large continuation indentation and short line length.  Welding 
+was being turned on and off in this case.  Normally welding is not done if
+all containers are on a single line, but an exception was made to detect 
+a situation like this and keep the welded string together. Updated 13 Jan 2021.
+
+
 =item B<Fixed incorrect guess of division vs pattern>
 
 A syntax error was produced in random testing when perltidy was fed
@@ -22,8 +73,7 @@ The formatted result is now
     sub _DR () { pi2 / 360 }
     sub _RD () { 360 / pi2 }
 
-This update was made 13 Jan 2021.
-
+This update was made 13 Jan 2021, a50ecf8.
 
 =item B<Correct formula for estimating line length with -wn option>
 
@@ -49,7 +99,7 @@ run with the following parameters
 
 caused an oscillation between two states.  An unusual feature which contributed
 to the problem is the very large ci value. This is fixed in a patch made 12 Jan
-2021.
+2021, 9a97dba.
 
 =back
 
-- 
2.39.5