[Debian-med-packaging] Bug#879248: r-cran-nmf FTBFS on some arches because of misuse of detectCores()

[Michael Cree]

Source: r-cran-nmf
Version: 0.20.6-1
Severity: wishlist

r-cran-nmf FTBFS on alpha, sparc64 and the non-linux arches, because
it calls R base function parallel::detectCores() and expects the
result to be an integer, however the detectCores() documentation
states that the result is an integer only if the number of CPU cores
is actually detected, and NA otherwise.  On the above mentioned
systems detectCores() fails to detect the number of CPUs thus returns
NA which leads to the failure to build in r-cran-nmf.

The problem is at line 81 of R/options.R which has:

        , pbackend= if( parallel::detectCores() > 1 ) 'par' else 'seq'

Presumably that code should be modified to assign detectCores() to a
variable and test for NA, and if it is NA just go with one core.

Use of detectCores() is also in R/parallel.R and presumably that
also should be checked for an NA returned value.

Cheers
Michael.