Bug #14674: New mismatched indentations warnings?

• Status: Closed
• Assignee: nobu (Nobuyoshi Nakada)
• Target version: 2.6
• ruby -v: ruby 2.6.0dev (2018-04-11 trunk 63132) [x86_64-darwin15]
• Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN

[marcandre (Marc-Andre Lafortune)]

I recently got a failure in my test suite because ruby head warns of indentation it considers mismatched:

$ ruby -w -e "
case
   when :foo
end
"
-e:3: warning: mismatched indentations at 'when' with 'case' at 2

I hope this is not intentional and will be fixed.

[shevegen (Robert A. Heiler)]

I think in the long run it would be nice if ruby hackers have more
control over non-error messages (e. g. warnings).

Some may prefer ruby providing cues for a more consistent code
layout but others may not necessarily care that much. In both
situations it would be nice to be able to decide on the verbosity
level of warnings.

[nobu (Nobuyoshi Nakada)]

It was intentional, but mismatched with your style?

[marcandre (Marc-Andre Lafortune)]

I strongly believe that it is not Ruby's parser job to warn us about styling, especially if there's no strong reason to suspect that it's a programmer error.

I realize rubocop is not official or part of MRI, but it has the required qualities to do this:

1. requires opt-in (i.e. users wanting to enforce a particular style can use rubocop; others don't need to)
2. configurable (i.e. rules can be turned off or tweaked)
3. exception can be dealt with with comments in the code (e.g. # rubocop:disable Some/Rule)
4. warning/errors are generated when desired, not all the time (e.g. during tests/manually, but not when actually running the code)

rubocop can even autocorrect according to these desired specs. Ruby MRI has none of these features!

Note that rubocop already supports Layout/CaseIndentation, can issue warning, error, or ignore it. It supports two different alignment styles, and supports any desired indent.

In short: warnings should be kept to a strict minimum in MRI, and enforcing a style for case/when is a terrible use of a warning.

Would you consider reverting this, or asking Matz?

[zverok (Victor Shepelev)]

I agree with @marcandre (Marc-Andre Lafortune). I used to prefer "indented when" style once, and still think it is pretty acceptable.

When Ruby has introduced interpreter warnings about mismatched indentation, I thought it is a good thing, allowing to catch obvious typos like this:

def foo
  bar.each do 
end # forgot to close do/end of "each", hard to spot after a large methods

#...

# Without that warning, the interpreter error about missing "end" at the very end of the file,
# far from the actual point of error

But for being useful this way, the interpreter should report only absolutely obvious and unambiguous typos, not "non-preferred style". Ruby is too mature to introduce hardcoded style preferences, I believe.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset trunk|r63141.

---

parse.y: when indent

• parse.y (k_when): warn less-indented when than case.
  [ruby-core:86492] [Bug #14674]