[ruby-core:100526] [Ruby master Bug#17283] Why does Dir.glob's ** match files in current directory?

[eregontp@gmail.com]

Issue #17283 has been updated by Eregon (Benoit Daloze).


Interestingly this behavior differs between Bash and Zsh:
```
$ tree
.
├── dir
│   └── subfile
└── foo

$ bash
$ echo **/*
dir/subfile

$ zsh -f   
$ echo **/*
dir dir/subfile foo
```

I think we cannot change the behavior for compatibility.

As a fun fact, `"**"` can even match the parent directory with `FNM_DOTMATCH` (#17280).

----------------------------------------
Bug #17283: Why does Dir.glob's ** match files in current directory?
https://bugs.ruby-lang.org/issues/17283#change-88149

* Author: Yanir (Yanir Name)
* Status: Open
* Priority: Normal
* ruby -v: ruby 2.7.2p137 (2020-10-01 revision 5445e04352) [x64-mingw32]
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN
----------------------------------------
If my current directory has 1 file and 1 dir, and I use `Dir.glob("**/*")` or even just `**`, both the dir and the file would be matched.

I would expect that only the dir will be matched, since the glob starts with `**`, which wants to match a directory. 
This is a behavior that's different from bash. In bash only the directory would be matched.

Ruby:
```
 Directory of C:\Users\User\z

10/24/2020  10:42 PM    <DIR>          .
10/24/2020  10:42 PM    <DIR>          ..
10/24/2020  10:42 PM    <DIR>          dir
10/24/2020  10:41 PM                 4 file
               1 File(s)              4 bytes
               3 Dir(s)  256,993,574,912 bytes free

C:\Users\User\z>irb
irb(main):001:0> Dir.glob("**/*")
=> ["dir", "file"]
irb(main):002:0> Dir.glob("**")
=> ["dir", "file"]
```

In Bash:
```
root@debian:~/rubytest# ls -lah
total 12K
drwxr-xr-x  3 root root 4.0K Oct 23 17:44 .
drwx------ 19 root root 4.0K Oct 23 17:43 ..
drwxr-xr-x  2 root root 4.0K Oct 23 17:44 dir
-rw-r--r--  1 root root    0 Oct 23 17:44 file
root@debian:~/rubytest# ls -lah **/*
-rw-r--r-- 1 root root 0 Oct 23 17:44 dir/subfile
```

**I know the behavior is not meant to be 1:1 to bash**. But this is still unexpected and doesn't make sense to me. Is this intended?

The documentation says:
```
**
Matches directories recursively.
```



-- 
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