[R-pkg-devel] Fortran compilation issues (errors/warnings) on Fedora clang/llvm

? Mon, 11 Dec 2023 10:02:14 +0000
Koen Hufkens <koen.hufkens at gmail.com> ?????:

error:
loc("/data/gannet/ripley/R/packages/incoming/rsofun.Rcheck/00_pkg_src/rsofun/src/interface_biosphere_biomee.mod.f90":105:62):
/data/gannet/ripley/Sources2/LLVM/17.0/llvm-project-17.0.3.src/flang/lib/Lower/ConvertType.cpp:392:
not yet implemented: derived type components with non default lower
bounds

Experience shows that reporting bugs in flang-new may get them
acknowledged but not fixed [1]. Have you tried detecting the flang-new
compiler from the ./configure script and only adding the workaround
flag if the compiler matches? Something like the following:

#!/bin/sh
# taken from Writing R Extensions, 1.2. Configure and cleanup
: ${R_HOME=`R RHOME`}
if test -z "${R_HOME}"; then
  echo "could not determine R_HOME"
  exit 1
fi
# determine the Fortran 9x compiler
FC="`"${R_HOME}/bin/R" CMD config FC`"
# Use --version output to determine the compiler
# A different compiler will either accept --version and print something
# else or fail due to "unknown argument". In both cases the branch will
# not be taken
if "$FC" --version 2>/dev/null | grep -q 'flang-new version 17'; then
 echo "PKG_FCFLAGS = `"${R_HOME}/bin/R" CMD config FCFLAGS`" \
  " -fc-prototypes-external" >>src/Makevars
fi

You will still get an "unsupported flag" warning on machines with
flang-new, but at least it won't warn with standards-compliant
compilers or crash with flang-new. Unfortunately, I don't know whether
this is acceptable for CRAN, sorry.

Good luck!

Best regards,
Ivan

[1] https://stat.ethz.ch/pipermail/r-package-devel/2023q4/009987.html