Bug #15576: Wrong error message from some class methods of `Dir`

• Status: Open
• Priority: Normal
• Assignee: -
• Target version: -
• ruby -v: ruby 2.6.0p0 (2018-12-25 revision 66547) [x86_64-linux]
• Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
• Tags: core, notbug

[takaram (Takuya Aramaki)]

When a error is raised in some class methods of Dir, the backtrace is as if the user called Dir.open.

$ ruby -e 'Dir.foreach {}'
Traceback (most recent call last):
    2: from -e:1:in `<main>'
    1: from -e:1:in `foreach'
-e:1:in `open': wrong number of arguments (given 0, expected 1) (ArgumentError)
$ ruby -e 'Dir.foreach(nil)'
Traceback (most recent call last):
    2: from -e:1:in `<main>'
    1: from -e:1:in `foreach'
-e:1:in `open': no implicit conversion of nil into String (TypeError)
$ ruby -e 'Dir.foreach("not_exist")'
Traceback (most recent call last):
    2: from -e:1:in `<main>'
    1: from -e:1:in `foreach'
-e:1:in `open': No such file or directory @ dir_initialize - not_exist (Errno::ENOENT)

The last line of the error message should be -e:1:in `foreach': ... like IO.foreach

This occurs in following methods:

• Dir.foreach
• Dir.entries
• Dir.each_child
• Dir.children

[nobu (Nobuyoshi Nakada)]

It is expected as these methods delegate to Dir.open.
So you can redefine the open method.

$ ruby -e 'def Dir.open(*)raise "boom";end; Dir.foreach("."){}'
Traceback (most recent call last):
    2: from -e:1:in `<main>'
    1: from -e:1:in `foreach'
-e:1:in `open': boom (RuntimeError)

whereas IO.foreach can't.

[nobu (Nobuyoshi Nakada)]

I'm not sure this difference between IO and Dir is intentional.