TypeError on assignment with a string containing special symbols using --readline

[stoyanovskiy239]

Description

Launch irb (1.2.6) with --readline option.
Execute the following:

a = '§'

Expected output:

 => "§"

Actual output:

Traceback (most recent call last):
        7: from /Users/sergey.stoyanovsky/.rvm/rubies/ruby-2.7.5/bin/irb:23:in `<main>'
        6: from /Users/sergey.stoyanovsky/.rvm/rubies/ruby-2.7.5/bin/irb:23:in `load'
        5: from /Users/sergey.stoyanovsky/.rvm/rubies/ruby-2.7.5/lib/ruby/gems/2.7.0/gems/irb-1.2.6/exe/irb:11:in `<top (required)>'
        4: from /Users/sergey.stoyanovsky/.rvm/rubies/ruby-2.7.5/lib/ruby/2.7.0/reline/unicode.rb:99:in `calculate_width'
        3: from /Users/sergey.stoyanovsky/.rvm/rubies/ruby-2.7.5/lib/ruby/2.7.0/reline/unicode.rb:99:in `scan'
        2: from /Users/sergey.stoyanovsky/.rvm/rubies/ruby-2.7.5/lib/ruby/2.7.0/reline/unicode.rb:108:in `block in calculate_width'
        1: from /Users/sergey.stoyanovsky/.rvm/rubies/ruby-2.7.5/lib/ruby/2.7.0/reline/unicode.rb:108:in `+'
TypeError (nil can't be coerced into Integer)

I suppose that output length calculation causes this since running the same assignment command after executing IRB.CurrentContext.omit_on_assignment = false before it produces proper output with no errors.

The following chain IRB::Irb#output_value -> Reline::Unicode#calculate_width -> Reline::Unicode#get_mbchar_width -> Reline.ambiguous_width leads to the uninitialized instance var @ambiguous_width, hence nil can't be coerced into Integer.

Result of irb_info

Ruby version: 2.7.5
IRB version: irb 1.2.6 (2020-09-14)
InputMethod: ReadlineInputMethod with ext/readline 8.1
.irbrc path: /Users/sergey.stoyanovsky/.rvm/rubies/ruby-2.7.5/.irbrc

Terminal Emulator

zsh

Setting Files

No ~/.irbrc.
My /Users/sergey.stoyanovsky/.rvm/rubies/ruby-2.7.5/.irbrc:

if ENV["rvm_path"].nil?
  require File.join(ENV["HOME"], "irbrc")
else
  require File.join(ENV["rvm_path"], "scripts", "irbrc")
end

[osyo-manga]

hi.
This problem seems to have been fixed in reline 0.2.0.

reline 0.1.5

$ irb --readline
irb(main):001:0> irb_info
=>
Ruby version: 2.7.5
IRB version: irb 1.2.6 (2020-09-14)
InputMethod: ReadlineInputMethod with ext/readline 8.0 and /home/worker/.inputrc
.irbrc path: /home/worker/_irbrc

irb(main):002:0> Reline::VERSION
=> "0.1.5"
irb(main):003:0> a = '§'
Traceback (most recent call last):
        7: from /home/worker/.rbenv/versions/2.7.5/bin/irb:23:in `<main>'
        6: from /home/worker/.rbenv/versions/2.7.5/bin/irb:23:in `load'
        5: from /home/worker/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/gems/irb-1.2.6/exe/irb:11:in `<top (required)>'
        4: from /home/worker/.rbenv/versions/2.7.5/lib/ruby/2.7.0/reline/unicode.rb:99:in `calculate_width'
        3: from /home/worker/.rbenv/versions/2.7.5/lib/ruby/2.7.0/reline/unicode.rb:99:in `scan'
        2: from /home/worker/.rbenv/versions/2.7.5/lib/ruby/2.7.0/reline/unicode.rb:108:in `block in calculate_width'
        1: from /home/worker/.rbenv/versions/2.7.5/lib/ruby/2.7.0/reline/unicode.rb:108:in `+'
TypeError (nil can't be coerced into Integer)

reline 0.2.0

$ gem install reline -v "0.2.0"
$ irb --readline
irb(main):001:0> irb_info
=>
Ruby version: 2.7.5
IRB version: irb 1.2.6 (2020-09-14)
InputMethod: ReadlineInputMethod with ext/readline 8.0 and /home/worker/.inputrc
.irbrc path: /home/worker/_irbrc

irb(main):002:0> Reline::VERSION
=> "0.2.0"
irb(main):003:0> a = '§'
=> "§"
irb(main):004:0>

Can installing reline 0.2.0 solve this problem?

$ gem install reline -v "0.2.0"

[stoyanovskiy239]

Yep, with reline 0.2.0 problem appears to be solved, thanks