[Rd] R 3.5.3 and 3.6.0 alpha Windows bug: UTF-8 characters in code are simplified to wrong ones

Tomáš Bořil bor||t @end|ng |rom gm@||@com
Wed Apr 10 18:13:52 CEST 2019

Yes, again in a script sourced by source(encoding = ...). But also by
typing it directly in R console.

Most of the time, I use RStudio as a front-end. For this experiment, I
also verified it in Rgui. In both front-ends, it behaves completely in
the same way.

An optional parameter to source() function which would translate all
UTF-8 characters in string literals to their "\Uxxxx" codes sounds as
a great idea (and I hope it would fix 99.9% of problems I have -
because that is the way I overcome these problems nowadays) - and the
same behaviour in command line...


> What do you mean it is "converted before"? Under what context? Again a
> script sourced by source(encoding=) ?
> And, are you using Rgui as front-end?

>>   The only problem is that I
>> cannot simple use enc2utf8("œ") - it is converted to "o" before
>> executing the function. Instead of that, I have to explicitly type
>> "\U00159" throughout my code.
On Wed, Apr 10, 2019 at 5:29 PM Tomas Kalibera <tomas.kalibera using gmail.com> wrote:
> On 4/10/19 3:02 PM, Tomáš Bořil wrote:
> > The thing is, I would rather prefer R (in that rare occasions where an
> > old function does not support anything but ANSI encoding) throwing  an
> > error:
> > "Unicode encoding not supported, please change the string in your
> > code" instead of silently converting some characters to different ones
> > without any warning.
> In principle it probably could be optional as Yihui Xie asks on R-devel,
> we will discuss that internally. If the Windows "best fit" is a big
> problem on its own, this is something that could be done quickly, if
> optional. We could turn into error only conversions that we have control
> of (inside R code), indeed, but that should be most.
> > I understand that there are some functions which are not
> > Unicode-compatible yet but according to the Stackoverflow discussion I
> > cited before, in many cases (90% or more?) everything works right with
> > Encoding("\U00159") == "UTF-8" (in my scripts, I have not found any
> > problem with explicit UTF-8 coding yet).
> Well there has been a lot of effort invested to make that possible, so
> that many internal string functions do not convert unnecessarily into
> UTF-8, mostly by Duncan Murdoch, but much more needs to be done and
> there is the problem with packages. Of course if you find a concrete R
> function that unnecessarily converts (source() is debatable, I know
> about it, so some other), you are welcome to report, I or someone can
> fix. A common problem is I/O (connections) and there the fix won't be
> easy, it would have to be re-designed. The problem is that when we have
> something typed "char *" inside R, it needs to be always in native
> encoding, any mix would lead to total chaos.
> The full solution would however only be fully switching to UTF-8
> internally on Windows (and then char * would always mean UTF-8), we have
> discussed this many times inside R Core (and many times before I
> joined), I am sure it will be discussed again at some point and we are
> aware of course of the problem. Please trust us it is hard to do - we
> know the code as we (collectively) have written it. People contributing
> to SO are users and package developers, not developers of the core. You
> can get more correct information from people on R-devel (package
> developers and sometimes core developers).
> >   The only problem is that I
> > cannot simple use enc2utf8("œ") - it is converted to "o" before
> > executing the function. Instead of that, I have to explicitly type
> > "\U00159" throughout my code.
> What do you mean it is "converted before"? Under what context? Again a
> script sourced by source(encoding=) ?
> And, are you using Rgui as front-end?
> > In my lectures, I have Czech, Russian and English students and it is
> > also impossible to create a script that works for everyone. In fact, I
> > know that Czech "ř" can be translated to my native (Czech) encoding. I
> > have just chosen the example as it is reproducible in English locale.
> > Originally, I had a problem with IPA characted (phonetic symbol) "œ",
> > i.e. "\U00153". In Czech locale, it is translated to "o". In English,
> > it is not converted - it remains "œ". But if I use "\U00153" in Czech
> > locale, nothing is converted and everything works right.
> Yes, the \u* sequence I hear is commonly used to represent UTF-8 string
> literals in something that is not UTF-8 itself. Note if you have a
> package, you can have R source files with UTF-8 encoded literal strings
> if you declare Encoding: UTF-8 in the DESCRIPTION file (see Writing R
> Extensions for details), even though sometimes people run into
> trouble/bugs as well.
> You probably know none of these problems exist on Linux nor macOS, where
> UTF-8 is the native encoding.
> Tomas
> >
> > Tomas
> >
> >
> >
> > On Wed, Apr 10, 2019 at 2:37 PM Tomas Kalibera <tomas.kalibera using gmail.com> wrote:
> >> On 4/10/19 2:06 PM, Tomáš Bořil wrote:
> >>
> >> Thank you for the explanation but I just do not understand one thing - why it would need to  recreate the R from a scratch to work with Unicode internally?
> >>
> >> If I call the script with
> >> eval(parse("script.R", encoding = "UTF-8"))
> >> it works perfectly - it looks like R functions already support Unicode. When I type "\U00159", R also has no problem with that.
> >>
> >> Well there is support for unicode, but the problem is that at some point translation to native encoding is needed. The parser does not do that, nothing you call in your example script does it, but many other functions do. Note that you can use UTF-8 without problems as long as you only have characters that can be represented also in the current native encoding. So, if you run in a Czech locale, Czech characters in UTF-8 will work fine, just they will sometimes be translated to corresponding Czech characters in your native encoding.
> >>
> >> If you want to learn more about encodings in R, look at ?Encoding, Writing R Extensions, etc. In principle, ever R object representing a string has a flag whether the string is in UTF-8, in latin1, or in current native encoding. But C structures typed "char *" almost always are in current native encoding, any mixture would lead to chaos. Most functions operating on strings have to specially handle UTF-8, MBCS encodings, ASCII, etc. All of that would have to be rewritten. Many Windows API calls are still using the native encoding version (some can use UTF16-LE via conversion from UTF-8 or other encodings).
> >>
> >> In principle, it should work to have UTF-8 coded string constants in R programs, and definitely so if you use \uxxxx (see Writing R Extensions for details). But you should always run in a native encoding where these characters can be represented, otherwise it may or may not work, depending on which functions you call.
> >>
> >> Tomas
> >>
> >>
> >> Thanks,
> >> Tomas
> >>
> >> st 10. 4. 2019 v 13:52 odesílatel Tomas Kalibera <tomas.kalibera using gmail.com> napsal:
> >>> On 4/10/19 1:35 PM, Tomáš Bořil wrote:
> >>>> Which users make their code depending on an automatic conversion which
> >>>> behaves differently in each Europe country, but only on Windows?
> >>> I meant the "best fit". The same R scripts for the same data sets would
> >>> be returning different results, people capture existing behavior without
> >>> necessarily knowing about it. Removing the "best fit" would not remove
> >>> the translation to native encoding, you would get NA or some escape
> >>> sequence/character code number instead of the "best fit" character.  It
> >>> would not solve the problem.
> >>>
> >>> The real problem is that the conversion to native encoding happens. This
> >>> question has been discussed many times before, but in short, it would
> >>> take probably many 1000s of hours of developer time to rewrite R to use
> >>> UTF-8 internally, but convert to UTF16-LE in all Windows API calls. It
> >>> will cause changes to documented behavior. What may not be obvious,
> >>> there is a problem with package code written in C/C++ that ignores
> >>> encoding flags (that is almost all native code in packages). That code
> >>> will stop working and there will be no way to test - because the input
> >>> data in the contributed examples/tests are ASCII.
> >>>
> >>> If Windows start supporting UTF-8 as native encoding, the fix will be a
> >>> lot easier (I hope ~100hours), and without the compatibility problems -
> >>> just users who would wish to use UTF-8 as native encoding will be
> >>> affected, and things will probably work for them even with poorly
> >>> written packages.
> >>>
> >>> Tomas
> >>>
> >>>
> >>>> If someone needs the explicit conversion, he can call the iconv() function.
> >>>>
> >>>> Much more people using R for text processing are frustrated they can
> >>>> code only in ASCII (0-255), even though their code is saved in
> >>>> Unicode.
> >>>>
> >>>> Tomas
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> On Wed, Apr 10, 2019 at 1:26 PM Tomas Kalibera <tomas.kalibera using gmail.com> wrote:
> >>>>> On 4/10/19 1:14 PM, Jeroen Ooms wrote:
> >>>>>> On Wed, Apr 10, 2019 at 12:19 PM Tomáš Bořil <borilt using gmail.com> wrote:
> >>>>>>> Minimalistic example:
> >>>>>>> Let's type "ř" (LATIN SMALL LETTER R WITH CARON) in RGui console:
> >>>>>>>> "ř"
> >>>>>>> [1] "r"
> >>>>>>>
> >>>>>>> Although the script is in UTF-8, the characters are replaced by
> >>>>>>> "simplified" substitutes uncontrollably (depending on OS locale). The
> >>>>>>> same goes with simply entering the code statements in R Console.
> >>>>>>>
> >>>>>>> The problem does not occur on OS with UTF-8 locale (Mac OS, Linux...)
> >>>>>> I think this is a "feature" of win_iconv that is bundled with base R
> >>>>>> on Windows (./src/extra/win_iconv). The character from your example is
> >>>>>> not part of the latin1 (iso-8859-1) set, however, win-iconv seems to
> >>>>>> do so anyway:
> >>>>>>
> >>>>>>> x <- "\U00159"
> >>>>>>> print(x)
> >>>>>> [1] "ř"
> >>>>>>> iconv(x, 'UTF-8', 'iso-8859-1')
> >>>>>> [1] "r"
> >>>>>>
> >>>>>> On MacOS, iconv tells us this character cannot be represented as latin1:
> >>>>>>
> >>>>>>> x <- "\U00159"
> >>>>>>> print(x)
> >>>>>> [1] "ř"
> >>>>>>> iconv(x, 'UTF-8', 'iso-8859-1')
> >>>>>> [1] NA
> >>>>>>
> >>>>>> I'm actually not sure why base-R needs win_iconv (but I'm not an
> >>>>>> encoding expert at all). Perhaps we could try to unbundle it and use
> >>>>>> the standard libiconv provided by the Rtools toolchain bundle to get
> >>>>>> more consistent results.
> >>>>> win_iconv just calls into Windows API to do the conversion, it is
> >>>>> technically easy to disable the "best fit" conversion, but I think it
> >>>>> won't be a good idea. In some cases, perhaps rare, the best fit is good,
> >>>>> actually including the conversion from "ř" to "r" which makes perfect
> >>>>> sense. But more importantly, changing the behavior could affect users
> >>>>> who expect the substitution to happen because it has been happening for
> >>>>> many years, and it won't help others much.
> >>>>>
> >>>>> Tomas
> >>>>>
> >>>>>> ______________________________________________
> >>>>>> R-devel using r-project.org mailing list
> >>>>>> https://stat.ethz.ch/mailman/listinfo/r-devel

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