Bug #16020: Forbid `if` `elsif` without a condition

• Status: Rejected
• Assignee: -
• Target version: -
• ruby -v: ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-linux]
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN

[bogdanvlviv (Bogdan Denkovych)]

Hello.

I might have missed something, but examples like:

if
  puts "!!!!1"
elsif
  puts "!!!!2"
elsif
  puts "!!!!3"
else
  puts "!!!!4"
end

# Output:
# !!!!1
# !!!!2
# !!!!3
# !!!!4

if false
  puts "!!!!1"
elsif 1==2
  puts "!!!!2"
elsif
  puts "!!!!3"
else
  puts "!!!!4"
end

# Output:
# !!!!3
# !!!!4

are confusing. We probably should raise SyntaxError in the case when if/elsif is being used without any condition. What do you think about it?

Original source: https://twitter.com/bogdanvlviv/status/1154356514628493313

Edited:

https://twitter.com/mamantoha/status/1154369189647454213 helped me to figure out that

The code like

if false
  puts "!!!!1"
elsif 1==2
  puts "!!!!2"
elsif
  puts "!!!!3"
else
  puts "!!!!4"
end

is similar to

if false
  puts "!!!!1"
elsif 1==2
  puts "!!!!2"
elsif (puts "!!!!3")
else (puts "!!!!4")
end

Probably Ruby should be more strict in those cases because such code is more prone to bugs.

[bogdanvlviv (Bogdan Denkovych)]

• ruby -v changed from ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-linux to ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-linux]

[bogdanvlviv (Bogdan Denkovych)]

• Description updated (diff)

[bogdanvlviv (Bogdan Denkovych)]

• Description updated (diff)

[znz (Kazuhiro NISHIYAMA)]

Rubocop can detect such bug.

https://rubocop.readthedocs.io/en/stable/cops_layout/#layoutconditionposition

[marcandre (Marc-Andre Lafortune)]

• Status changed from Open to Rejected