R devel - Feb 2023 - Undocumented change of dirname("C:/") on R-devel on Windows

Hi Tomas,

There has been an R CMD check error with xfun and r-devel on Windows for a
while:
https://www.r-project.org/nosvn/R.check/r-devel-windows-x86_64/xfun-00check.html
Basically it means that the following would return TRUE before:

  normalizePath('a/b', mustWork = FALSE) ==
normalizePath('./a/b', mustWork
= FALSE)

but it became FALSE at some point in r-devel. I think 'a/b' and
'./a/b`
should be treated as the same path. Does that make sense? Thanks!

Regards,
Yihui
--
https://yihui.org


On Thu, Feb 23, 2023 at 11:44 PM Hiroaki Yutani <yutani.ini at gmail.com>
wrote:
> I confirmed the revert fixed my failing test. Thanks!
>
> 2023?2?23?(?) 20:12 Hiroaki Yutani <yutani.ini at gmail.com>:
>
> > Thanks for the prompt response, I'll confirm it after the new
R-devel
> > binary is available.
> > Also, thanks for the detailed explanation. I agree with you in
general.
> >
> > > "/" in "C:/" is a path separator or not, and
whether it is trailing or
> > not
> >
> > It seems a Windows' path basically consists of two components; a
drive
> > specification (e.g., C:) and the directory structure within the drive.
> What
> > I learned today is that both "C:/" and "C:" are
valid path
> specifications,
> > but refer to different locations; "C:" is not the root
directory of the
> > drive, but just a relative path [1]. So, I agree with you that the
> basename
> > of "C:/" should be "C:/". However, at the same
time, I don't feel this is
> > worth a breaking change, so I think we can preserve the current (R
4.2.2)
> > behavior.
> >
> > [1]:
> >
>
https://learn.microsoft.com/en-us/dotnet/standard/io/file-path-formats#apply-the-current-directory
> >
> > Best,
> > Yutani
> >
> > 2023?2?23?(?) 17:15 Tomas Kalibera <tomas.kalibera at
gmail.com>:
> >
> >>
> >> On 2/23/23 03:27, Hiroaki Yutani wrote:
> >> > Hi,
> >> >
> >> > I found dirname() behaves differently on R-devel on Windows.
Since I'm
> >> not
> >> > sure which behavior is right, let me ask here before filing
this to
> R's
> >> > Bigzilla.
> >> >
> >> > On R 4.2.2., we get
> >> >
> >> >      > dirname("C:/")
> >> >      [1] "C:/"
> >> >
> >> > However, on R-devel (r83888), we get
> >> >
> >> >      > dirname("C:/")
> >> >      [1] "."
> >> >
> >> > ?dirname says 'dirname returns the part of the path up to
but
> excluding
> >> the
> >> > last path separator, or "." if there is no path
separator,' but I
> don't
> >> see
> >> > how the root path is supposed to be treated based on this
rule (,
> >> whether
> >> > it's WIndows or UNIX-alike).
> >> Thanks for spotting the difference, I've reverted to the
previous
> >> behavior, the change was unintentional. If you spot any other
suspicious
> >> changes in behavior in file-system operations, please report.
> >> > What should we expect as the return value of
dirname("C:/")? I feel
> the
> >> > current behavior on R 4.2.2 is right, but I'd like to
confirm.
> >>
> >> I also think the old behavior is better, even though it could be
argued
> >> whether the "/" in "C:/" is a path separator
or not, and whether it is
> >> trailing or not. But the behavior is in line with Unix where
dirname of
> >> "/" is also "/". Msys2 would return
"C:".
> >>
> >> If  "/" in "C:/" is a path separator but not a
trailing path separator,
> >> then basename("C:/") should probably be "" and
not "C:", and this would
> >> be in line with what R does on Unix. However, to be in line with
Unix, I
> >> think the basename of "C:/" should be "C:/".
Yet, Msys2 returns "C:"
> >> which is what R does now.
> >>
> >> So what these functions should do on Windows is definitely tricky.
In
> >> either case the behavior is now again as in R 4.2.2.
> >>
> >> Best
> >> Tomas
> >>
> >> >
> >> > Best,
> >> > Yutani
> >> >
> >> >       [[alternative HTML version deleted]]
> >> >
> >> > ______________________________________________
> >> > R-devel at r-project.org mailing list
> >> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >>
> >
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
	[[alternative HTML version deleted]]

On 2/27/23 17:02, Yihui Xie wrote:
> Hi Tomas,
>
> There has been an R CMD check error with xfun and r-devel on Windows 
> for a while: 
>
https://www.r-project.org/nosvn/R.check/r-devel-windows-x86_64/xfun-00check.html
> Basically it means that the following would?return TRUE before:
>
> ? normalizePath('a/b', mustWork = FALSE)
==?normalizePath('./a/b',
> mustWork = FALSE)
>
> but it became FALSE at some point in r-devel. I think 'a/b' and 
> './a/b` should be treated as the same path. Does?that make sense?
Thanks!
Thanks a lot for spotting and reporting this, fixed in R-devel. 
Normalization of non-existent paths was broken.

Best
Tomas
>
> Regards,
> Yihui
> --
> https://yihui.org
>
>
> On Thu, Feb 23, 2023 at 11:44 PM Hiroaki Yutani <yutani.ini at
gmail.com>
> wrote:
>
>     I confirmed the revert fixed my failing test. Thanks!
>
>     2023?2?23?(?) 20:12 Hiroaki Yutani <yutani.ini at gmail.com>:
>
>     > Thanks for the prompt response, I'll confirm it after the new
>     R-devel
>     > binary is available.
>     > Also, thanks for the detailed explanation. I agree with you in
>     general.
>     >
>     > > "/" in "C:/" is a path separator or not,
and whether it is
>     trailing or
>     > not
>     >
>     > It seems a Windows' path basically consists of two components;
a
>     drive
>     > specification (e.g., C:) and the directory structure within the
>     drive. What
>     > I learned today is that both "C:/" and "C:"
are valid path
>     specifications,
>     > but refer to different locations; "C:" is not the root
directory
>     of the
>     > drive, but just a relative path [1]. So, I agree with you that
>     the basename
>     > of "C:/" should be "C:/". However, at the same
time, I don't
>     feel this is
>     > worth a breaking change, so I think we can preserve the current
>     (R 4.2.2)
>     > behavior.
>     >
>     > [1]:
>     >
>    
https://learn.microsoft.com/en-us/dotnet/standard/io/file-path-formats#apply-the-current-directory
>     >
>     > Best,
>     > Yutani
>     >
>     > 2023?2?23?(?) 17:15 Tomas Kalibera <tomas.kalibera at
gmail.com>:
>     >
>     >>
>     >> On 2/23/23 03:27, Hiroaki Yutani wrote:
>     >> > Hi,
>     >> >
>     >> > I found dirname() behaves differently on R-devel on
Windows.
>     Since I'm
>     >> not
>     >> > sure which behavior is right, let me ask here before
filing
>     this to R's
>     >> > Bigzilla.
>     >> >
>     >> > On R 4.2.2., we get
>     >> >
>     >> >? ? ? > dirname("C:/")
>     >> >? ? ? [1] "C:/"
>     >> >
>     >> > However, on R-devel (r83888), we get
>     >> >
>     >> >? ? ? > dirname("C:/")
>     >> >? ? ? [1] "."
>     >> >
>     >> > ?dirname says 'dirname returns the part of the path
up to but
>     excluding
>     >> the
>     >> > last path separator, or "." if there is no path
separator,'
>     but I don't
>     >> see
>     >> > how the root path is supposed to be treated based on this
rule (,
>     >> whether
>     >> > it's WIndows or UNIX-alike).
>     >> Thanks for spotting the difference, I've reverted to the
previous
>     >> behavior, the change was unintentional. If you spot any other
>     suspicious
>     >> changes in behavior in file-system operations, please report.
>     >> > What should we expect as the return value of
dirname("C:/")?
>     I feel the
>     >> > current behavior on R 4.2.2 is right, but I'd like to
confirm.
>     >>
>     >> I also think the old behavior is better, even though it could
>     be argued
>     >> whether the "/" in "C:/" is a path
separator or not, and
>     whether it is
>     >> trailing or not. But the behavior is in line with Unix where
>     dirname of
>     >> "/" is also "/". Msys2 would return
"C:".
>     >>
>     >> If? "/" in "C:/" is a path separator but
not a trailing path
>     separator,
>     >> then basename("C:/") should probably be ""
and not "C:", and
>     this would
>     >> be in line with what R does on Unix. However, to be in line
>     with Unix, I
>     >> think the basename of "C:/" should be
"C:/". Yet, Msys2 returns
>     "C:"
>     >> which is what R does now.
>     >>
>     >> So what these functions should do on Windows is definitely
>     tricky. In
>     >> either case the behavior is now again as in R 4.2.2.
>     >>
>     >> Best
>     >> Tomas
>     >>
>     >> >
>     >> > Best,
>     >> > Yutani
>     >> >
>     >> >? ? ? ?[[alternative HTML version deleted]]
>     >> >
>     >> > ______________________________________________
>     >> > R-devel at r-project.org mailing list
>     >> > https://stat.ethz.ch/mailman/listinfo/r-devel
>     >>
>     >
>
>     ? ? ? ? [[alternative HTML version deleted]]
>
>     ______________________________________________
>     R-devel at r-project.org mailing list
>     https://stat.ethz.ch/mailman/listinfo/r-devel
>
	[[alternative HTML version deleted]]