On 22/12/2017 10:46 AM, Marc Schwartz wrote:
Hi,
See inline below.
On Dec 22, 2017, at 9:12 AM, Martin Maechler <maech...@stat.math.ethz.ch> wrote:
Duncan Murdoch <murdoch.dun...@gmail.com>
on Thu, 21 Dec 2017 14:23:13 -0500 writes:
On 21/12/2017 1:02 PM, Winston Chang wrote:
On recent builds of R-devel, R CMD check gives a
WARNING when some compiler warning flags are detected,
such as -Werror, because they are non-portable. This
appears to have been added in this commit:
https://github.com/wch/r-source/commit/2e80059
That is not the canonical R sources.
Yes, that is obvious. The main page for that repository
says it is a mirror of the R sources, right at the top. I
know that because I put the message there, and because I
see it every time I visit the repository. If you have a
good way of pointing people to the changes made in a
commit with the canonical R sources, please let us
know. I and many others would be happy to use it.
The usual way is just to refer to the revision number,
i.e. "This appears to have been added in rev 73909".
People who don't have the sources checked out can see the
diff on your Github mirror using
https://github.com/wch/r-source/search?q="trunk@73909"&type=Commits
and following the listed search hit. (Thanks to Thierry
Onkelinx for helping me with this.) This only works for
commits to the trunk. I guessed that something like
https://github.com/wch/r-source/search?q="R-3-4-branch@73937"&type=Commits
would work if the commit was to the 3.4 branch, but
apparently not. I don't know how to find those commits.
Presumably there's a way, but I don't know it.
Another possibility is that someone could set up (or
already has?) one of the web viewers (WebSVN, etc.) for
the real repository. That would be better for those of us
who are SVN users, but probably harder for Git users.
Duncan Murdoch
As you know I had setup (the first few versions of) the svn at
https://svn.r-project.org/
at the time, I wanted to keep that machine protected as much as
possible and had decided not to install any other apache
modules and svn - niceties just such that the server would run
minimal services and hence would be minimally vulnerable.
The times have changed though and I will look into adding WebSVN
to svn.r-project.org as one of the first things in 2018.
Martin Maechler
Martin,
Just to play a bit of a devil's advocate here, WebSVN has not been
updated/maintained since June of 2011, so is a number of years old at this
point. That should raise some reasonable concerns over bugs, security issues
and related matters.
To put that in perspective, the last update to WebSVN was around the time that
R 2.13.1 was released.
That general pattern, of SVN clients not being actively maintained, seems to be
consistent across a number of the web based (and even browser plugin based) SVN
clients, which may in turn, be an indication of the general shift to Git in
recent years, much as the shift from CVS to SVN occurred years ago.
In researching other SVN clients, the few that still seem to be actively
maintained are typically dedicated desktop clients/GUIs, that in some cases are
closed source and/or are OS specific.
One of the few web based SVN clients that still seems to be actively maintained
is Trac (https://trac.edgewall.org), however it is under a modified BSD
license, which may raise some issues and from what I can tell, may be more
complicated in terms of set up, since it also supports bug tracking, wiki and
other functionality. As with any such application, there would be ongoing
maintenance issues as well.
There's also ViewVC which still seems to be active.
I am not advocating any particular solution. I just want to point out potential issues
with WebSVN and raise for discussion, what options may make sense to consider, based upon
how many folks might actually use such "live" web based functionality versus
remote SVN access via a desktop client, which is certainly an option, since they won't
have write access anyway.
As a general principle in open source projects the work should be done
by the people who want to use the product. Winston wanted git access to
the R sources, and he put it together: bravo!
It's unfortunate that git doesn't really support svn completely, because
it is superior in many ways. However, it isn't uniformly better than
svn. Its very weak support for sequential labels means that switching to
it would be a lot of work for R Core, and that group doesn't have a lot
of spare time to waste.
The one negative aspect of Winston's effort is caused by this weakness.
If you tell me that something happened in revision 73909, I know it was
recent. If you tell me that something appeared in commit 2e80059, it
wastes my time looking up that commit and putting it in context.
Duncan Murdoch
Also, a number of the Git desktop clients also support Git SVN
(https://git-scm.com/docs/git-svn), for compatibility, which offers Git users
an alternative to using a dedicated desktop SVN client.
Regards,
Marc
And your description seems wrong: there is now an
_optional_ check controlled by an environment variable,
primarily for CRAN checks.
The check is "optional", but not for packages submitted
to CRAN.
I'm working on a package where these compiler warning
flags are present in a Makefile generated by a
configure script -- that is, the configure script
detects whether the compiler supports these flags, and
if so, puts them in the Makefile. (The configure script
is for a third-party C library which is in a
subdirectory of src/.)
Because the flags are added only if the system supports
them, there shouldn't be any worries about portability
in practice.
Please read the explanation in the manual: there are
serious concerns about such flags which have bitten CRAN
users several times.
To take your example, you cannot know what -Werror does
on all compilers (past, present or future) where it is
supported (and -W flags do do different things on
different compilers). On current gcc it does
-Werror Make all warnings into errors.
and so its effect depends on what other flags are used
(people typically use -Wall, and most new versions of
both gcc and clang add more warnings to -Wall -- I read
this week exactly such a discussion about the
interaction of -Werror with
-Wtautological-constant-compare as part of -Wall in
clang trunk).
Is there a way to get R CMD check to not raise warnings
in cases like this? I know I could modify the C
library's configure.ac (which is used to generate the
configure script) but I'd prefer to leave the library's
code untouched if possible.
You don't need to (and most likely should not) use the
C[XX]FLAGS it generates ... just use the flags which R
passes to the package to use.
It turns out that there isn't even a risk of these
compiler flags being used -- I learned from of my
colleagues that the troublesome compiler flags, like
-Werror, never actually appear in the Makefile. The
configure script prints out those compiler flags out when
it checks for them, but in the end it creates a Makefile
with the CFLAGS inherited from R. So there's no chance
that the library would be compiled using those flags
(unless R passed them along).
His suggested workaround is to silence the output of the
configure script. That also hides some useful
information, but it does work for this issue.
-Winston
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