hi,

After some discussion the eclass evolved and is ready for the next round
of discussion.

justin

# Copyright 1999-2011 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: $

# Author Justin Lecher <jlec@g.o>
# Test functions provided by Sebastien Fabbro and Kacper Kowalik

# @ECLASS: fortran-2.eclass
# @MAINTAINER:
# jlec@g.o
# sci@g.o
# @BLURB: Packages, which need a fortran compiler should inherit this eclass.
# @DESCRIPTION:
# If you need a fortran compiler, inherit this eclass. This eclass tests for
# working fortran compilers and exports the variables FC and F77.
# Optional, it checks for openmp capability of the
# current fortran compiler through FORTRAN_NEED_OPENMP=1.
# Only phase function exported is pkg_pretend and pkg_setup.
# Need help? Ask the sci team.

# @ECLASS-VARIABLE: FORTRAN_NEED_OPENMP
# @DESCRIPTION:
# Set FORTRAN_NEED_OPENMP=1 in order to test FC for openmp capabilities
#
# Default is 0

# @ECLASS-VARIABLE: FORTRAN_STANDARD
# @DESCRIPTION:
# Set this, if a special dialect needs to be support. Generally not needed.
#
# Valid settings are any combination of
#
# FORTRAN_STANDARD="77 90 95 2003"
#
# Defaults to FORTRAN_STANDARD="77" which is sufficient for most cases.

inherit toolchain-funcs

DEPEND="virtual/fortran"
RDEPEND="${DEPEND}"

# internal function
#
# FUNCTION: _write_testsuite
# DESCRIPTION: writes fortran test code
_write_testsuite() {
	local filebase=${T}/test-fortran

	# f77 code
	cat <<- EOF > "${filebase}.f"
	       end
	EOF

	# f90/95 code
	cat <<- EOF > "${filebase}.f90"
	end
	EOF

	# f2003 code
	cat <<- EOF > "${filebase}.f03"
	       procedure(), pointer :: p
	       end
	EOF
}

# internal function
#
# FUNCTION: _compile_test
# DESCRIPTION:
# Takes fortran compiler as first argument and dialect as second.
# Checks whether the passed fortran compiler speaks the fortran dialect
_compile_test() {
	local filebase=${T}/test-fortran
	local fcomp=${1}
	local fdia=${2}

	[[ -z ${fcomp} ]] && die "_compile_test() needs at least one argument"

	[[ -f "${filebase}.f${fdia}" ]] || _write_testsuite

	${fcomp} "${filebase}.f${fdia}" -o "${filebase}-f${fdia}" >&/dev/null
	local ret=$?

	rm -f "${filebase}-f${fdia}"
	return ${ret}
}

# internal function
#
# FUNCTION: _fortran-has-openmp
# DESCRIPTION:
# See if the fortran supports OpenMP.
_fortran-has-openmp() {
	local flag
	local filebase=${T}/test-fc-openmp

	cat <<- EOF > "${filebase}.f"
	       call omp_get_num_threads
	       end
	EOF

	for flag in -fopenmp -xopenmp -openmp -mp -omp -qsmp=omp; do
		$(tc-getFC "$@") ${flag} "${filebase}.f" -o "${filebase}" >&/dev/null
		local ret=$?
		(( ${ret} )) || break
	done

	rm -f "${filebase}"*
	return ${ret}
}

# internal
#
# FUNCTION: _die_msg
# DESCRIPTION: Detailed description how to handle fortran support
_die_msg() {
	echo
	eerror "Please install currently selected gcc version with USE=fortran."
	eerror "If you intend to use a different compiler then gfortran, please"
	eerror "set FC variable accordingly and take care that the neccessary"
	eerror "fortran dialects are support."
	echo
	die "Currently no working fortran compiler is available"
}

# @FUNCTION: fortran-2_pkg_pretend
# @DESCRIPTION:
# Setup functionallity, checks for a valid fortran compiler and optionally for its openmp support.
fortran-2_pkg_pretend() {
	local dialect

	[[ -n ${F77} ]] || F77=$(tc-getFC)

	: ${FORTRAN_STANDARD:=77}
	for dialect in ${FORTRAN_STANDARD}; do
		case ${dialect} in
			77) _compile_test $(tc-getF77) || _die_msg ;;
			90|95) _compile_test $(tc-getFC) 90 || _die_msg ;;
			2003) _compile_test $(tc-getFC) 03 || _die_msg ;;
			2008) die "Future" ;;
			*) die "${dialect} is not a Fortran dialect." ;;
		esac
	done

	if [[ ${FORTRAN_NEED_OPENMP} == 1 ]]; then
		_fortran-has-openmp || \
			die "Please install current gcc with USE=openmp or set the FC variable to a compiler that supports OpenMP"
	fi
}

# @FUNCTION: fortran-2_pkg_setup
# @DESCRIPTION:
# In EAPI < 4 it calls the compiler check. This behavior is deprecated
# and will be removed at 01-Sep-2011. Please migrate to EAPI=4.
#
# Exports the FC and F77 variable according to the compiler checks.
fortran-2_pkg_setup() {
	if has ${EAPI:-0} 0 1 2 3; then
		ewarn "The support for EAPI=${EAPI} by the fortran-2.eclass"
		ewarn "will be end at 01-Sep-2011"
		ewarn "Please migrate your package to EAPI=4"
		fortran-2_pkg_pretend
	fi
	[[ -n ${F77} ]] || export F77=$(tc-getFC)
	[[ -n ${FC} ]] || export FC=$(tc-getFC)
}

case "${EAPI:-0}" in
	1|2|3) EXPORT_FUNCTIONS pkg_setup ;;
	4) EXPORT_FUNCTIONS pkg_pretend pkg_setup ;;
	*) die "EAPI=${EAPI} is not supported" ;;
esac