[ruby-core:106005] [Ruby master Bug#18170] Exception#inspect should not include newlines

["Eregon (Benoit Daloze)" <noreply@ruby-lang.org>]

Issue #18170 has been updated by Eregon (Benoit Daloze).


BTW it seems `irb` disables `error_highlight` somehow:
```
$ ruby -ve 'self.instance_off'
ruby 3.1.0dev (2021-11-08T13:15:21Z master bd2674ad33) [x86_64-linux]
-e:1:in `<main>': undefined method `instance_off' for main:Object (NoMethodError)

self.instance_off
    ^^^^^^^^^^^^^
Did you mean?  instance_of?
```
vs
```
$ irb
irb(main):001:0> self.instance_off
(irb):1:in `<main>': undefined method `instance_off' for main:Object (NoMethodError)
Did you mean?  instance_of?
	from /home/eregon/prefix/ruby-master/lib/ruby/gems/3.1.0/gems/irb-1.3.8.pre.11/exe/irb:11:in `<top (required)>'
	from /home/eregon/.rubies/ruby-master/bin/irb:25:in `load'
	from /home/eregon/.rubies/ruby-master/bin/irb:25:in `<main>'
```

----------------------------------------
Bug #18170: Exception#inspect should not include newlines
https://bugs.ruby-lang.org/issues/18170#change-94553

* Author: mame (Yusuke Endoh)
* Status: Assigned
* Priority: Normal
* Assignee: mame (Yusuke Endoh)
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
Is this intentional?

```
p StandardError.new("foo\nbar")
#=>
# #<StandardError: foo
# bar>
```

I expect `#inspect` returns a one-line string. How about returning `#<StandardError: "foo\nbar">` or something?

Recently, multi-line error messages have been increasing by the introduction of did_you_mean and error_highlight. Printing an object that contains such an exception leads to a tricky output:

```
class Foo
  def initialize
    @exception = begin; exampl; rescue Exception; $!; end
  end

  def example
  end
end

p Foo.new
#=>
# #<Foo:0x00007f15aeb4ba48 @exception=#<NameError: undefined local variable or method `exampl' for #<Foo:0x00007f15aeb4ba48 ...>
#
#     @exception = begin; exampl; rescue Exception; $!; end
#                         ^^^^^^
# Did you mean?  example>>
```

This issue was originally found by @ioquatix 



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