[ruby-core:103709] [Ruby master Bug#17846] Percent mode changes the output from ERB beyond what is documented

Issue #17846 has been updated by k0kubun (Takashi Kokubun).

Status changed from Feedback to Rejected

So the trick is:

```rb
$ erb -x repro.erb
#coding:UTF-8
_erbout = +'';  # ; _erbout.<< "x\n".freeze
; _erbout.<< "y\n".freeze
; _erbout
```

```rb
$ erb -x -P repro.erb
#coding:UTF-8
_erbout = +'';  # ; _erbout.<< "x\ny\n".freeze

; _erbout
```

At glance, the generated code seems broken. However, @xtkoba made the point; `<%#` is a special token of ERB that allows a Ruby comment, whereas `<% #` is a Ruby expression with a comment. I think writing a comment in the middle of `<% %>` is currently not supported. For your case, you should just use `<%#` instead of `<% #`.

----------------------------------------
Bug #17846: Percent mode changes the output from ERB beyond what is documented
https://bugs.ruby-lang.org/issues/17846#change-91802

* Author: graywolf (Gray Wolf)
* Status: Rejected
* Priority: Normal
* ruby -v: ruby 2.7.3p183 (2021-04-05 revision 6847ee089d) [x86_64-linux-musl]
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
```
/ # cat repro.erb
<% # %>x
y
/ # erb repro.erb
y
/ # erb -P repro.erb
/ #
```

Based on documentation of -P (disabling percent mode), this change in behavior
is unexpected.




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