From f3dbee1eb437a28f7b614b752232f3bd938bde39 Mon Sep 17 00:00:00 2001
From: Steve Hancock <perltidy@users.sourceforge.net>
Date: Mon, 2 Aug 2021 18:57:04 -0700
Subject: [PATCH] Fix edge case of formatting instability, b1186

---
 dev-bin/run_convergence_tests.pl.data | 30 +++++++++++++++++++++++++++
 lib/Perl/Tidy/Formatter.pm            | 20 +++++++++++++-----
 local-docs/BugLog.pod                 |  9 ++++++++
 3 files changed, 54 insertions(+), 5 deletions(-)

diff --git a/dev-bin/run_convergence_tests.pl.data b/dev-bin/run_convergence_tests.pl.data
index 2fe5c841..f1461684 100644
--- a/dev-bin/run_convergence_tests.pl.data
+++ b/dev-bin/run_convergence_tests.pl.data
@@ -6931,6 +6931,36 @@ ok(  (  Win32::GetFullPathName(
 --vertical-tightness=2
 --weld-nested-containers
 
+==> b1186.in <==
+# S1
+sub null_to_zzempty { }
+sub entab {
+
+          return
+            $table->{
+                    null_to_zzempty ( $row )
+            }->{ null_to_zzempty ( $col ) };
+}
+
+# S2
+sub null_to_zzemptY { }
+
+sub entaB {
+
+          return
+            $table->{ null_to_zzemptY (
+                                    $row ) }
+            ->{ null_to_zzemptY ( $col ) };
+}
+
+==> b1186.par <==
+--indent-columns=10
+--line-up-parentheses
+--maximum-line-length=44
+--paren-tightness=0
+--paren-vertical-tightness=2
+--space-function-paren
+
 ==> b120.in <==
 # Same as bug96
 # State 1
diff --git a/lib/Perl/Tidy/Formatter.pm b/lib/Perl/Tidy/Formatter.pm
index d2d1bc52..5c801e73 100644
--- a/lib/Perl/Tidy/Formatter.pm
+++ b/lib/Perl/Tidy/Formatter.pm
@@ -17140,10 +17140,12 @@ my %is_kwiZ;
 BEGIN {
 
     # Added 'w' to fix b1172
-    my @q = qw(k w i Z);
+    my @q = qw(k w i Z ->);
     @is_kwiZ{@q} = (1) x scalar(@q);
 }
 
+use constant DEBUG_FIND_START => 0;
+
 sub find_token_starting_list {
 
     # When testing to see if a block will fit on one line, some
@@ -17169,7 +17171,14 @@ sub find_token_starting_list {
         # a previous comma is a good break point
         # $i_opening_minus = $i_opening_paren;
     }
-    elsif ( $tokens_to_go[$i_opening_paren] eq '(' ) {
+
+    elsif (
+        $tokens_to_go[$i_opening_paren] eq '('
+
+        # non-parens added here to fix case b1186
+        || $is_kwiZ{$type_prev_nb}
+      )
+    {
         $i_opening_minus = $im1;
 
         # Walk back to improve length estimate...
@@ -17184,11 +17193,12 @@ sub find_token_starting_list {
         if ( $types_to_go[$i_opening_minus] eq 'b' ) { $i_opening_minus++ }
     }
 
-    # Handle non-parens
-    elsif ( $is_kwiZ{$type_prev_nb} ) { $i_opening_minus = $iprev_nb }
-
   RETURN:
 
+    DEBUG_FIND_START && print <<EOM;
+FIND_START: i=$i_opening_paren tok=$tokens_to_go[$i_opening_paren] => im=$i_opening_minus tok=$tokens_to_go[$i_opening_minus]
+EOM
+
     return $i_opening_minus;
 }
 
diff --git a/local-docs/BugLog.pod b/local-docs/BugLog.pod
index dadd9848..cf543f87 100644
--- a/local-docs/BugLog.pod
+++ b/local-docs/BugLog.pod
@@ -2,6 +2,15 @@
 
 =over 4
 
+=item B<Fix edge case of formatting instability, b1186>.
+
+Testing with random parameters produced a case of instability involving
+parameter -lp -pvt=n and a short maximum line length.
+
+This fixes case b1186.
+
+2 Aug 2021.
+
 =item B<Fix edge case of formatting instability, b1185>.
 
 Testing with random parameters produced a case of welding instability involving
-- 
2.39.5