[ruby-core:109693] [Ruby master Bug#18970] CRuby adds an invalid header to bin/bundle (and others) which makes it unusable in Bash on Windows

["nobu (Nobuyoshi Nakada)" <noreply@ruby-lang.org>]

Issue #18970 has been updated by nobu (Nobuyoshi Nakada).


MSP-Greg (Greg L) wrote in #note-12:
> Windows bash file 'top'
> 
> ```bash
> {
> bindir=$(dirname "$0")
> exec "$bindir/ruby" "-x" "$0" "$@"
> }
> #!/usr/bin/env ruby
> ```

I'm not sure where the header came from.
`rbinstall.rb` doesn't use `dirname` command.
Maybe [here](https://github.com/MSP-Greg/ruby-loco-test/blob/master/mswin/copy_bash_scripts.rb#L15)?

> Windows *.cmd or *.bat binstub
> ```bat
> @ECHO OFF
> @"%~dp0ruby.exe" -x "%~dpn0" %*
> ```

Nor `@ECHO OFF`.


----------------------------------------
Bug #18970: CRuby adds an invalid header to bin/bundle (and others) which makes it unusable in Bash on Windows
https://bugs.ruby-lang.org/issues/18970#change-98919

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN
----------------------------------------
Same as https://github.com/oneclick/rubyinstaller2/issues/299, but I figured it's extremely likely to be a bug in CRuby and not in RubyInstaller2.

The original user issue is: https://github.com/ruby/setup-ruby/issues/371.
`bundle` does not work in a Bash shell on Windows -- without an extra `gem install bundler` --, and the reason is building CRuby on Windows either does not produce a `bin/bundle` or it has the wrong permissions and the wrong start.

I downloaded all latest releases from https://github.com/ruby/setup-ruby/blob/master/windows-versions.json and extracted them (I'm on Linux FWIW).
```
$ ls
rubyinstaller-2.4.10-1-x64     rubyinstaller-2.6.10-1-x64     rubyinstaller-3.0.4-1-x64     rubyinstaller-head-x64     ruby-mswin
rubyinstaller-2.4.10-1-x64.7z  rubyinstaller-2.6.10-1-x64.7z  rubyinstaller-3.0.4-1-x64.7z  rubyinstaller-head-x64.7z  ruby-mswin.7z
rubyinstaller-2.5.9-1-x64      rubyinstaller-2.7.6-1-x64      rubyinstaller-3.1.2-1-x64     ruby-mingw                 ruby-ucrt
rubyinstaller-2.5.9-1-x64.7z   rubyinstaller-2.7.6-1-x64.7z   rubyinstaller-3.1.2-1-x64.7z  ruby-mingw.7z              ruby-ucrt.7z
```

Of course only Ruby 2.7+ ships with Bundler, so for <=2.6 it's expected to be missing.

```
$ ls -l */bin/bundle
-rw-r--r--. 1 eregon eregon 707 Apr 19 22:22 rubyinstaller-3.1.2-1-x64/bin/bundle
-rw-r--r--. 1 eregon eregon 707 Aug 19 22:40 rubyinstaller-head-x64/bin/bundle
-rw-rw-rw-. 1 eregon eregon 564 Aug 20 11:15 ruby-mingw/bin/bundle
-rw-rw-rw-. 1 eregon eregon 829 Aug 20 11:09 ruby-mswin/bin/bundle
-rw-rw-rw-. 1 eregon eregon 564 Aug 20 11:20 ruby-ucrt/bin/bundle
```

So only 3.1 and head have bin/bundle.
But those 2 bin/bundle do not have the executable bit set.

They also start like this which sounds invalid for Bash:
```
$ cat rubyinstaller-3.1.2-1-x64/bin/bundle
:""||{ ""=> %q<-*- ruby -*-
@"%~dp0ruby" -x "%~f0" %*
@exit /b %ERRORLEVEL%
};{ #
bindir="${0%/*}" #
exec "$bindir/ruby" "-x" "$0" "$@" #
>,
}
#!/usr/bin/env ruby
#
# This file was generated by RubyGems.
...
```

On https://github.com/eregon/setup-ruby/runs/7843304711?check_suite_focus=true we can see 3.0, 3.1 and head fail for `echo ~ && which -a bundle` in bash.
2.7 avoids the issue in that CI run because the Bundler version is considered too old by setup-ruby and so `gem install bundler` is done there.

## Needed fix

In general, I think it is *very* important that CRuby does NOT modify files in `bin/`, and so that they are exactly the same as when RubyGems would write them when installing the corresponding gem.
This has been a problem not only here but also in these two other issues:
* `gem install bundler` fails on Windows, needs `--force` to workaround: https://github.com/rubygems/rubygems/issues/5245
* `gem install bundler` fails on `--enable-load-relative` Rubies: https://github.com/ruby/setup-ruby/issues/98#issuecomment-719950719

`tool/rbinstall.rb` seems to be responsible for changing the `bin/` files and therefore causing those bugs:
https://github.com/ruby/ruby/blob/209631a45f9682dedf718f4b4a140efe7d21a6fc/tool/rbinstall.rb#L487
Can we remove that?

Not that this issue cannot be solved in RubyGems, it's CRuby breaking `bin/bundle` (and others) in Bash on Windows.



-- 
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