From 69cd27c98eafd8711056825cf6c378eee282ffaa Mon Sep 17 00:00:00 2001
From: aycabta <aycabta@gmail.com>
Date: Tue, 24 Mar 2020 13:56:22 +0900
Subject: [PATCH] [ruby/reline] Suppress error when check ambiguous char width
 in LANG=C

https://github.com/ruby/reline/commit/623dffdd75
---
 lib/reline.rb | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/lib/reline.rb b/lib/reline.rb
index 2708cd91b5..1537ee7e69 100644
--- a/lib/reline.rb
+++ b/lib/reline.rb
@@ -336,8 +336,14 @@ module Reline
       @ambiguous_width = 2 if Reline::IOGate == Reline::GeneralIO or STDOUT.is_a?(File)
       return if ambiguous_width
       Reline::IOGate.move_cursor_column(0)
-      output.write "\u{25bd}"
-      @ambiguous_width = Reline::IOGate.cursor_pos.x
+      begin
+        output.write "\u{25bd}"
+      rescue Encoding::UndefinedConversionError
+        # LANG=C
+        @ambiguous_width = 1
+      else
+        @ambiguous_width = Reline::IOGate.cursor_pos.x
+      end
       Reline::IOGate.move_cursor_column(0)
       Reline::IOGate.erase_after_cursor
     end