[Rd] Error: package or namespace load failed for‘utils

[Kurt Hornik]

>>>>> Laurent Gautier writes:

> In case a search engine leads someone with the same issue here, I am
> documenting the point I reached:

> I can reproduce the issue with a small example when forcing R to not load
> any package at startup time (using an Renviron file):
> ```
> package <- "utils"
> lib.loc <- "<fill this according to your R install>"
> ns <- loadNamespace(package, lib.loc)
> ```

I cannot reproduce this using current R-devel or R-patched.  After
starting with R_DEFAULT_PACKAGES=NULL,

R> search()
[1] ".GlobalEnv"   "Autoloads"    "package:base"
R> loadedNamespaces()
[1] "compiler" "tools"    "base"    
R> package <- "utils"
R> lib.loc <- file.path(R.home(), "library")
R> ns <- loadNamespace(package, lib.loc)
R> loadedNamespaces()
[1] "compiler" "tools"    "utils"    "base"    

-k

> The code path goes through `registerS3methods(nsInfo$S3methods, package,
> env)` and there to:

> ```
> if (methods::is(genfun, "genericFunction"))
> ```

> The evaluation of `methods::is` reaches the line triggering the error as
> `.identC(class1, class2)` and `.identC(class2, "ANY")` both return `NA` and
> `NA || NA` is not defined:

> ```
>> if (NA || NA) { cat("here\n") }
> Error in if (NA || NA) { : missing value where TRUE/FALSE needed
> ```

> As I understand it `.identC()` should never return `NA`, and if the case
> this would mean that R itself is an unstable state (something at the C
> level that should not have happened has happened) but this was not caught
> earlier.

> 	[[alternative HTML version deleted]]

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