with_language() fails to reset the cache on Alpine Linux

[bastistician]

withr/R/language.R

Lines 48 to 50 in 35301f6

	# resets the cache. So if there's some OS/setup that this technique fails
	# on, we might try bindtextdomain() instead or as well.
	local_locale(c(LC_MESSAGES = ""), .local_envir = .local_envir)

Yes there is: musl-based Alpine Linux.
example("with_language") gives:

wth_ln> with_language("en", try(mean[[1]]))
Error in mean[[1]] : object of type 'closure' is not subsettable

wth_ln> with_language("fr", try(mean[[1]]))
Error in mean[[1]] : objet de type 'closure' non indiçable

wth_ln> with_language("es", try(mean[[1]]))
Error in mean[[1]] : objet de type 'closure' non indiçable

All subsequent invocations of that error message stick to French.

R CMD checking withr fails for me from

withr/tests/testthat/test-language.R

Line 6 in 35301f6

expect_error(with_language("es", mean[[1]]), "no es subconjunto")

due to this issue.

In R >= 4.2.0, bindtextdomain(NULL) could be used to flush the cache, as in Sys.setLanguage(). This works on Alpine Linux:

> Sys.setLanguage("en"); try(mean[[1]])
Error in mean[[1]] : object of type 'closure' is not subsettable
> Sys.setLanguage("fr"); try(mean[[1]])
Error in mean[[1]] : objet de type 'closure' non indiçable
> Sys.setLanguage("es"); try(mean[[1]])
Error in mean[[1]] : objeto de tipo 'closure' no es subconjunto

sessionInfo()

R Under development (unstable) (2023-02-09 r83794)
Platform: x86_64-pc-linux-musl (64-bit)
Running under: Alpine Linux v3.17

Matrix products: default
BLAS:   /home/smeyer/QA/R-83794/build/lib/libRblas.so 
LAPACK: /home/smeyer/QA/R-83794/build/lib/libRlapack.so;  LAPACK version 3.11.0

locale:
[1] C.UTF-8 C       C       C       C       C      

time zone: Europe/Berlin
tzcode source: internal

[lionel-]

cc @hadley

[maelle]

@KevCaz noticed this bug in my post about potools

I observe the same behavior as @bastistician (on Ubuntu)

library("withr")
with_language("en", try(mean[[1]]))
#> Error in mean[[1]] : object of type 'closure' is not subsettable
with_language("fr", try(mean[[1]]))
#> Error in mean[[1]] : objet de type 'closure' non indiçable
with_language("es", try(mean[[1]]))
#> Error in mean[[1]] : objeto de tipo 'closure' no es subconjunto
try(mean[[1]])
#> Error in mean[[1]] : objeto de tipo 'closure' no es subconjunto

with_language("fr", try(mean[[1]]))
#> Error in mean[[1]] : objet de type 'closure' non indiçable
try(mean[[1]])
#> Error in mean[[1]] : objet de type 'closure' non indiçable

^{Created on 2023-10-09 with reprex v2.0.2}

[lionel-]

I had to also set LANG / LC_ALL in my unit tests: 08619ef. Does that fix it for you @maelle?

@hadley I wonder if we should try and set it automatically if not set already? We'd use some country as default for each language. To override, the user could supply a length-2 character vector. It might be tricky to have the mapping be both comprehensive and cross-platform.

[maelle]

I had to change the locale code to make your example work on my machine but that seems to be expected for different OS. 😅

It seems to work!

with_lang <- function(lc, language, expr) {
  withr::local_envvar(c(LC_ALL = lc))
  withr::local_language(language)
  expr
}

with_lang("fr_FR.UTF-8", "fr", try(mean[[1]]))
#> Error in mean[[1]] : objet de type 'closure' non indiçable
try(mean[[1]])
#> Error in mean[[1]] : object of type 'closure' is not subsettable

^{Created on 2023-10-09 with reprex v2.0.2}

[hadley]

@lionel- do we need to set LC_ALL to the matching language, or can we just set it to something other than C? Should we be using Sys.setLanguage() in versions of R that provide it?

[lionel-]

After some reading including https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=931456 and https://bugs.r-project.org/show_bug.cgi?id=18055 here is my understanding of things:

• LANGUAGE doesn't do anything when LC_ALL is set to C (see https://www.gnu.org/software/gettext/manual/html_node/The-LANGUAGE-variable.html) which is why I had to set LC_ALL in unit tests to override platforms where it is set to C (e.g. one of Kurt's Debian machines IIRC). This is an entirely separate problem.

• There are cache invalidation bugs in GNU libc that require workarounds to force a reset. Setting LC_ALL / LANG envvars, like I did for the aforementioned issue, is one of them but should not be necessary here. We can use other workarounds, for instance the one Hadley experimented with in Try using bindtextdomain() for cache clearing #183, or the one Martin implemented in Sys.setLanguage() with bindtextdomain(NULL). For now I think I'd rather use Hadley's approach until we can drop support for R < 4.2.0, since Martin's workaround won't work on these older R versions.

[bastistician]

Thanks! I can confirm that applying Commit a57401a (#183) on the current CRAN version 2.5.2 resolves the check failure for me: "Status: OK". 👍

[lionel-]

Thanks for checking!