[R-pkg-devel] Package Encoding and Literal Strings

[Tomas Kalibera]

On 12/16/20 11:07 PM, joris using jorisgoosen.nl wrote:
> David,
>
> Thanks for the response!
>
> So the problem is a bit worse then just setting `encoding="UTF-8"` on
> functions like readLines.
> I'll describe our setup a bit:
> So we run R embedded in a separate executable and through a whole bunch of
> C(++) magic get that to the main executable that runs the actual interface.
> All the code that isn't R basically uses UTF-8. This works good and we've
> made sure that all of our source code is encoded properly and I've verified
> that for this particular problem at least my source file is definitely
> encoded in UTF-8 (Ive checked a hexdump).
>
> The simplest solution, that we initially took, to get R+Windows to
> cooperate with everything is to simply set the locale to "C" before
> starting R. That way R simply assumes UTF-8 is native and everything worked
> splendidly. Until of course a file needs to be opened in R that contains
> some non-ASCII characters. I noticed the problem because a korean user had
> hangul in his username and that broke everything. This because R was trying
> to convert to a different locale than Windows was using.

Setting locale to "C" does not make R assume UTF-8 is the native 
encoding, there is no way to make UTF-8 the current native encoding in R 
on the current builds of R on Windows. This is an old limitation of 
Windows, only recently fixed by Microsoft in recent Windows 10 and with 
UCRT Windows runtime (see my blog post [1] for more - to make R support 
this we need a new toolchain to build R).

If you set the locale to C encoding, you are telling R the native 
encoding is C/POSIX (essentially ASCII), not UTF-8. Encoding-sensitive 
operations, including conversions, including those conversions that 
happen without user control e.g. for interacting with Windows, will 
produce incorrect results (garbage) or in better case errors, warnings, 
omitted, substituted or transliterated characters.

In principle setting the encoding via locale is dangerous on Windows, 
because Windows has two current encodings, not just one. By setting 
locale you set the one used in the C runtime, but not the other one used 
by the system calls. If all code (in R, packages, external libraries) 
was perfect, this would still work as long as all strings used were 
representable in both encodings. For other strings it won't work, and 
then code is not perfect in this regard, it is usually written assuming 
there is one current encoding, which common sense dictates should be the 
case. With the recent UTF-8 support ([1]), one can switch both of these 
to UTF-8.

> The solution I've now been working on is:
> I took the sourcecode of R 4.0.3 and changed the backend of "gettext" to
> add an `encoding="something something"` option. And a bit of extra stuff
> like `bind_textdomain_codeset` in case I need to tweak the codeset/charset
> that gettext uses.
> I think I've got that working properly now and once I solve the problem of
> the encoding in a pkg I will open a bugreport/feature-request and I'll add
> a patch that implements it.

A number of similar "shortcuts" have been added to R in the past, but 
they may the code more complex, harder to maintain and use, and can't 
realistically solve all of these problems, anyway. Strings will 
eventually be assumed to be in what is the current native encoding by 
the C library. In R, any external code R uses, or code R packages use. 
Now that Microsoft finally is supporting UTF-8, the way to get out of 
this is switching to UTF-8. This needs only small changes to R source 
code compared to those "shortcuts" (or to using UTF-16LE). I'd be 
against polluting the code with any more "shortcuts".

> The problem I'm stuck with now is simply this:
> I have an R pkg here that I want to test the translations with and the code
> is definitely saved as UTF-8, the package has "Encoding: UTF-8" in the
> DESCRIPTION and it all loads and works. The particular problem I have is
> that the R code contains literally: `mathotString <- "Mathôt!"`
> The actual file contains the hexadecimal representation of ô as proper
> utf-8: "0xC3 0xB4" but R turns it into: "0xf4".
> Seemingly on loading the package, because I haven't done anything with it
> except put it in my debug c-function to print its contents as
> hexadecimals...
>
> The only thing I want to achieve here is that when R loads the package it
> keeps those strings in their original UTF-8 encoding, without converting it
> to "native" or the strange unicode codepoint it seemingly placed in there
> instead. Because otherwise I cannot get gettext to work fully in UTF-8 mode.
>
> Is this already possible in R?

In principle, working with strings not representable in the current 
encoding is not reliable (and never will be). It can still work in some 
specific cases and uses. Parsing a UTF-8 string literal from a file, 
with correctly declared encoding as documented in WRE, should work at 
least in single-byte encodings. But what happens after that string is 
parsed is another thing. The parsing is based internally on using these 
"shortcuts", that is lying to a part of the parser about the encoding, 
and telling the rest of the parser that it is really something else (not 
native, but UTF-8). The part that is being "lied to" may get confused or 
not. It would not when the real native encoding is say latin1, a common 
case in the past for which the hack was created, but it might when it is 
a double-byte encoding that conflicts with the text being parsed in 
dangerous ways. This is also why this hack only makes sense for string 
literals (and comments), and still only to a limit as the strings may be 
misinterpreted later after parsing.

So a really short summary is: you can only reliably use strings 
representable in the current encoding in R, and that encoding cannot be 
UTF-8 on Windows in released versions of R. There is an experimental 
version, see [1], if you could experiment with that and see whether that 
might work for your applications, could try to find and report bugs 
there (e.g. to me directly), that would be useful.

If you find behavior re encodings in released versions of R that 
contradicts the current documentation, please report with a minimal 
reproducible example, such cases should be fixed (even though sometimes 
the "fix" would be just changing the documentation, the effort really 
should be now for supporting UTF-8 for real). Specifically with 
"mathotString", you might try creating  an example that does not include 
any package (just calls to parse with encoding options set), only then 
gradually adding more of package loading if that does not reproduce. It 
would be important to know the current encoding (sessionInfo, l10n_info).

Best,
Tomas

[1] 
https://developer.r-project.org/Blog/public/2020/07/30/windows/utf-8-build-of-r-and-cran-packages/index.html

>
> Cheers,
> Joris

>
>
> On Wed, 16 Dec 2020 at 20:15, David Bosak <dbosak01 using gmail.com> wrote:
>
>> Joris:
>>
>>
>>
>> I’ve fought with encoding problems on Windows a lot.  Here are some
>> general suggestions.
>>
>>
>>
>>     1. Put “@encoding UTF-8” on any Roxygen comments.
>>     2. Put “encoding = “UTF-8” on any functions like writeLines or
>>     readLines that read/write to a text file.
>>     3. This post:
>>     https://kevinushey.github.io/blog/2018/02/21/string-encoding-and-r/
>>
>>
>>
>> If you have a more specific problem, please describe and we can try to
>> help.
>>
>>
>>
>> David
>>
>>
>>
>> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
>> Windows 10
>>
>>
>>
>> *From: *joris using jorisgoosen.nl
>> *Sent: *Wednesday, December 16, 2020 1:52 PM
>> *To: *r-package-devel using r-project.org
>> *Subject: *[R-pkg-devel] Package Encoding and Literal Strings
>>
>>
>>
>> Hello All,
>>
>>
>>
>> Some context, I am one of the programmers of a software pkg (
>>
>> https://jasp-stats.org/) that uses an embedded instance of R to do
>>
>> statistics. And make that a bit easier for people who are intimidated by R
>>
>> or like to have something more GUI oriented.
>>
>>
>>
>>
>>
>> We have been working on translating the interface but ran into several
>>
>> problems related to encoding of strings. We prefer to use UTF-8 for
>>
>> everything and this works wonderful on unix systems, as is to be expected.
>>
>>
>>
>> Windows however is a different matter. Currently I am working on some local
>>
>> changes to "do_gettext" and some related internal functions of R to be able
>>
>> to get UTF-8 encoded output from there.
>>
>>
>>
>> But I ran into a bit of a problem and I think this mailinglist is probably
>>
>> the best place to start.
>>
>>
>>
>> It seems that if I have an R package that specifies "Encoding: UTF-8" in
>>
>> DESCRIPTION the literal strings inside the package are converted to the
>>
>> local codeset/codepage regardless of what I want.
>>
>>
>>
>> Is it possible to keep the strings in UTF-8 internally in such a pkg
>>
>> somehow?
>>
>>
>>
>> Best regards,
>>
>> Joris Goosen
>>
>> University of Amsterdam
>>
>>
>>
>>                  [[alternative HTML version deleted]]
>>
>>
>>
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>>
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>>
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>>
>>
>>
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>
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