# Copyright 1999-2013 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: /var/cvsroot/gentoo-x86/eclass/haskell-cabal.eclass,v 1.42 2013/11/20 09:19:19 slyfox Exp $

# @ECLASS: haskell-cabal.eclass
# @MAINTAINER:
# Haskell herd <haskell@gentoo.org>
# @AUTHOR:
# Original author: Andres Loeh <kosmikus@gentoo.org>
# Original author: Duncan Coutts <dcoutts@gentoo.org>
# @BLURB: for packages that make use of the Haskell Common Architecture for Building Applications and Libraries (cabal)
# @DESCRIPTION:
# Basic instructions:
#
# Before inheriting the eclass, set CABAL_FEATURES to
# reflect the tools and features that the package makes
# use of.
#
# Currently supported features:
#   haddock    --  for documentation generation
#   hscolour   --  generation of colourised sources
#   hoogle     --  generation of documentation search index
#   alex       --  lexer/scanner generator
#   happy      --  parser generator
#   c2hs       --  C interface generator
#   cpphs      --  C preprocessor clone written in Haskell
#   profile    --  if package supports to build profiling-enabled libraries
#   bootstrap  --  only used for the cabal package itself
#   bin        --  the package installs binaries
#   lib        --  the package installs libraries
#   nocabaldep --  don't add dependency on cabal.
#                  only used for packages that _must_ not pull the dependency
#                  on cabal, but still use this eclass (e.g. haskell-updater).
#   test-suite --  add support for cabal test-suites (introduced in Cabal-1.8)

inherit eutils ghc-package multilib

# @ECLASS-VARIABLE: CABAL_EXTRA_CONFIGURE_FLAGS
# @DESCRIPTION:
# User-specified additional parameters passed to 'setup configure'.
# example: /etc/portage/make.conf: CABAL_EXTRA_CONFIGURE_FLAGS=--enable-shared
: ${CABAL_EXTRA_CONFIGURE_FLAGS:=}

# @ECLASS-VARIABLE: CABAL_EXTRA_BUILD_FLAGS
# @DESCRIPTION:
# User-specified additional parameters passed to 'setup build'.
# example: /etc/portage/make.conf: CABAL_EXTRA_BUILD_FLAGS=-v
: ${CABAL_EXTRA_BUILD_FLAGS:=}

# @ECLASS-VARIABLE: GHC_BOOTSTRAP_FLAGS
# @DESCRIPTION:
# User-specified additional parameters for ghc when building
# _only_ 'setup' binary bootstrap.
# example: /etc/portage/make.conf: GHC_BOOTSTRAP_FLAGS=-dynamic to make
# linking 'setup' faster.
: ${GHC_BOOTSTRAP_FLAGS:=}

# @ECLASS-VARIABLE: CABAL_DEBUG_LOOSENING
# @DESCRIPTION:
# Show debug output for 'cabal_chdeps' function if set.
# Needs working 'diff'.
: ${CABAL_DEBUG_LOOSENING:=}

HASKELL_CABAL_EXPF="pkg_setup src_compile src_test src_install"

case "${EAPI:-0}" in
	2|3|4|5) HASKELL_CABAL_EXPF+=" src_configure" ;;
	*) ;;
esac

EXPORT_FUNCTIONS ${HASKELL_CABAL_EXPF}

for feature in ${CABAL_FEATURES}; do
	case ${feature} in
		haddock)    CABAL_USE_HADDOCK=yes;;
		hscolour)   CABAL_USE_HSCOLOUR=yes;;
		hoogle)     CABAL_USE_HOOGLE=yes;;
		alex)       CABAL_USE_ALEX=yes;;
		happy)      CABAL_USE_HAPPY=yes;;
		c2hs)       CABAL_USE_C2HS=yes;;
		cpphs)      CABAL_USE_CPPHS=yes;;
		profile)    CABAL_USE_PROFILE=yes;;
		bootstrap)  CABAL_BOOTSTRAP=yes;;
		bin)        CABAL_HAS_BINARIES=yes;;
		lib)        CABAL_HAS_LIBRARIES=yes;;
		nocabaldep) CABAL_FROM_GHC=yes;;
		test-suite) CABAL_TEST_SUITE=yes;;
		*) CABAL_UNKNOWN="${CABAL_UNKNOWN} ${feature}";;
	esac
done

if [[ -n "${CABAL_USE_HADDOCK}" ]]; then
	IUSE="${IUSE} doc"
	# don't require depend on itself to build docs.
	# ebuild bootstraps docs from just built binary
	[[ ${CATEGORY}/${PN} = "dev-haskell/haddock" ]] || DEPEND="${DEPEND} doc? ( dev-haskell/haddock )"
fi

if [[ -n "${CABAL_USE_HSCOLOUR}" ]]; then
	IUSE="${IUSE} hscolour"
	DEPEND="${DEPEND} hscolour? ( dev-haskell/hscolour )"
fi

if [[ -n "${CABAL_USE_ALEX}" ]]; then
	DEPEND="${DEPEND} dev-haskell/alex"
fi

if [[ -n "${CABAL_USE_HAPPY}" ]]; then
	DEPEND="${DEPEND} dev-haskell/happy"
fi

if [[ -n "${CABAL_USE_C2HS}" ]]; then
	DEPEND="${DEPEND} dev-haskell/c2hs"
fi

if [[ -n "${CABAL_USE_CPPHS}" ]]; then
	DEPEND="${DEPEND} dev-haskell/cpphs"
fi

if [[ -n "${CABAL_USE_PROFILE}" ]]; then
	IUSE="${IUSE} profile"
fi

if [[ -n "${CABAL_TEST_SUITE}" ]]; then
	IUSE="${IUSE} test"
fi

# We always use a standalone version of Cabal, rather than the one that comes
# with GHC. But of course we can't depend on cabal when building cabal itself.
if [[ -z ${CABAL_MIN_VERSION} ]]; then
	CABAL_MIN_VERSION=1.1.4
fi
if [[ -z "${CABAL_BOOTSTRAP}" && -z "${CABAL_FROM_GHC}" ]]; then
	DEPEND="${DEPEND} >=dev-haskell/cabal-${CABAL_MIN_VERSION}"
fi

# returns the version of cabal currently in use
_CABAL_VERSION_CACHE=""
cabal-version() {
	if [[ -z "${_CABAL_VERSION_CACHE}" ]]; then
		if [[ "${CABAL_BOOTSTRAP}" ]]; then
			# We're bootstrapping cabal, so the cabal version is the version
			# of this package itself.
			_CABAL_VERSION_CACHE="${PV}"
		elif [[ "${CABAL_FROM_GHC}" ]]; then
			local cabal_package=$(echo "$(ghc-libdir)"/Cabal-*)
			# /path/to/ghc/Cabal-${VER} -> ${VER}
			_CABAL_VERSION_CACHE="${cabal_package/*Cabal-/}"
		else
			# We ask portage, not ghc, so that we only pick up
			# portage-installed cabal versions.
			_CABAL_VERSION_CACHE="$(ghc-extractportageversion dev-haskell/cabal)"
		fi
	fi
	echo "${_CABAL_VERSION_CACHE}"
}

cabal-bootstrap() {
	local setupmodule
	local cabalpackage
	if [[ -f "${S}/Setup.lhs" ]]; then
		setupmodule="${S}/Setup.lhs"
	elif [[ -f "${S}/Setup.hs" ]]; then
		setupmodule="${S}/Setup.hs"
	else
		die "No Setup.lhs or Setup.hs found"
	fi

	if [[ -z "${CABAL_BOOTSTRAP}" && -z "${CABAL_FROM_GHC}" ]] && ! ghc-sanecabal "${CABAL_MIN_VERSION}"; then
		eerror "The package dev-haskell/cabal is not correctly installed for"
		eerror "the currently active version of ghc ($(ghc-version)). Please"
		eerror "run haskell-updater or re-build dev-haskell/cabal."
		die "cabal is not correctly installed"
	fi

	# We build the setup program using the latest version of
	# cabal that we have installed
	cabalpackage=Cabal-$(cabal-version)
	einfo "Using cabal-$(cabal-version)."

	make_setup() {
		set -- -package "${cabalpackage}" --make "${setupmodule}" \
			${GHC_BOOTSTRAP_FLAGS} \
			"$@" \
			-o setup
		echo $(ghc-getghc) ${HCFLAGS} "$@"
		$(ghc-getghc) "$@"
	}
	if $(ghc-supports-shared-libraries); then
		# # some custom build systems might use external libraries,
		# # for which we don't have shared libs, so keep static fallback
		# bug #411789, http://hackage.haskell.org/trac/ghc/ticket/5743#comment:3
		# http://hackage.haskell.org/trac/ghc/ticket/7062
		# http://hackage.haskell.org/trac/ghc/ticket/3072
		# ghc does not set RPATH for extralibs, thus we do it ourselves by hands
		einfo "Prepending $(ghc-libdir) to LD_LIBRARY_PATH"
		if [[ ${CHOST} != *-darwin* ]]; then
			LD_LIBRARY_PATH="$(ghc-libdir)${LD_LIBRARY_PATH:+:}${LD_LIBRARY_PATH}"
			export LD_LIBRARY_PATH
		else
			DYLD_LIBRARY_PATH="$(ghc-libdir)${DYLD_LIBRARY_PATH:+:}${DYLD_LIBRARY_PATH}"
			export DYLD_LIBRARY_PATH
		fi
		{ make_setup -dynamic "$@" && ./setup --help >/dev/null; } ||
		make_setup "$@" || die "compiling ${setupmodule} failed"
	else
		make_setup "$@" || die "compiling ${setupmodule} failed"
	fi
}

cabal-mksetup() {
	local setupdir

	if [[ -n $1 ]]; then
		setupdir=$1
	else
		setupdir=${S}
	fi

	rm -f "${setupdir}"/Setup.{lhs,hs}

	echo 'import Distribution.Simple; main = defaultMainWithHooks defaultUserHooks' \
		> $setupdir/Setup.hs || die "failed to create default Setup.hs"
}

cabal-hscolour() {
	set -- hscolour "$@"
	echo ./setup "$@"
	./setup "$@" || die "setup hscolour failed"
}

cabal-haddock() {
	set -- haddock "$@"
	echo ./setup "$@"
	./setup "$@" || die "setup haddock failed"
}

cabal-hscolour-haddock() {
	# --hyperlink-source implies calling 'setup hscolour'
	set -- haddock --hyperlink-source
	echo ./setup "$@"
	./setup "$@" --hyperlink-source || die "setup haddock --hyperlink-source failed"
}

cabal-die-if-nonempty() {
	local breakage_type=$1
	shift

	[[ "${#@}" == 0 ]] && return 0
	eerror "Detected ${breakage_type} packages: ${@}"
	die "//==-- Please, run 'haskell-updater' to fix ${breakage_type} packages --==//"
}

cabal-show-brokens() {
	# pretty-printer
	$(ghc-getghcpkg) check 2>&1 \
		| egrep -v '^Warning: haddock-(html|interfaces): ' \
		| egrep -v '^Warning: include-dirs: '

	cabal-die-if-nonempty 'broken' \
		$($(ghc-getghcpkg) check --simple-output)
}

cabal-show-old() {
	cabal-die-if-nonempty 'outdated' \
		$("${EPREFIX}"/usr/sbin/haskell-updater --quiet --upgrade --list-only)
}

cabal-show-brokens-and-die() {
	cabal-show-brokens
	cabal-show-old

	die "$@"
}

cabal-configure() {
	has "${EAPI:-0}" 0 1 2 && ! use prefix && EPREFIX=

	if [[ -n "${CABAL_USE_HADDOCK}" ]] && use doc; then
		cabalconf="${cabalconf} --with-haddock=${EPREFIX}/usr/bin/haddock"
	fi
	if [[ -n "${CABAL_USE_PROFILE}" ]] && use profile; then
		cabalconf="${cabalconf} --enable-library-profiling"
	fi
	if [[ -n "${CABAL_USE_ALEX}" ]]; then
		cabalconf="${cabalconf} --with-alex=${EPREFIX}/usr/bin/alex"
	fi

	if [[ -n "${CABAL_USE_HAPPY}" ]]; then
		cabalconf="${cabalconf} --with-happy=${EPREFIX}/usr/bin/happy"
	fi

	if [[ -n "${CABAL_USE_C2HS}" ]]; then
		cabalconf="${cabalconf} --with-c2hs=${EPREFIX}/usr/bin/c2hs"
	fi
	if [[ -n "${CABAL_USE_CPPHS}" ]]; then
		cabalconf="${cabalconf} --with-cpphs=${EPREFIX}/usr/bin/cpphs"
	fi
	if [[ -n "${CABAL_TEST_SUITE}" ]]; then
		cabalconf="${cabalconf} $(use_enable test tests)"
	fi

	local option
	for option in ${HCFLAGS}
	do
		cabalconf+=" --ghc-option=$option"
	done

	# Building GHCi libs on ppc64 causes "TOC overflow".
	if use ppc64; then
		cabalconf="${cabalconf} --disable-library-for-ghci"
	fi

	# currently cabal does not respect CFLAGS and LDFLAGS on it's own (bug #333217)
	# so translate LDFLAGS to ghc parameters (without filtering)
	local flag
	for flag in $LDFLAGS; do cabalconf="${cabalconf} --ghc-option=-optl$flag"; done

	# disable executable stripping for the executables, as portage will
	# strip by itself, and pre-stripping gives a QA warning.
	# cabal versions previous to 1.4 does not strip executables, and does
	# not accept the flag.
	# this fixes numerous bugs, amongst them;
	# bug #251881, bug #251882, bug #251884, bug #251886, bug #299494
	cabalconf="${cabalconf} --disable-executable-stripping"

	cabalconf="${cabalconf} --docdir=${EPREFIX}/usr/share/doc/${PF}"
	# As of Cabal 1.2, configure is quite quiet. For diagnostic purposes
	# it's better if the configure chatter is in the build logs:
	cabalconf="${cabalconf} --verbose"

	# We build shared version of our Cabal where ghc ships it's shared
	# version of it. We will link ./setup as dynamic binary againt Cabal later.
	[[ ${CATEGORY}/${PN} == "dev-haskell/cabal" ]] && \
		$(ghc-supports-shared-libraries) && \
			cabalconf="${cabalconf} --enable-shared"

	if $(ghc-supports-shared-libraries); then
		# maybe a bit lower
		if $(ghc-supports-dynamic-by-default); then
			cabalconf="${cabalconf} --enable-shared"
		fi
	fi

	set -- configure \
		--ghc --prefix="${EPREFIX}"/usr \
		--with-compiler="$(ghc-getghc)" \
		--with-hc-pkg="$(ghc-getghcpkg)" \
		--prefix="${EPREFIX}"/usr \
		--libdir="${EPREFIX}"/usr/$(get_libdir) \
		--libsubdir=${P}/ghc-$(ghc-version) \
		--datadir="${EPREFIX}"/usr/share/ \
		--datasubdir=${P}/ghc-$(ghc-version) \
		${cabalconf} \
		${CABAL_CONFIGURE_FLAGS} \
		${CABAL_EXTRA_CONFIGURE_FLAGS} \
		"$@"
	echo ./setup "$@"
	./setup "$@" || cabal-show-brokens-and-die "setup configure failed"
}

cabal-build() {
	unset LANG LC_ALL LC_MESSAGES
	set --  build ${CABAL_EXTRA_BUILD_FLAGS} "$@"
	echo ./setup "$@"
	./setup "$@" \
		|| die "setup build failed"
}

cabal-copy() {
	has "${EAPI:-0}" 0 1 2 && ! use prefix && ED=${D}

	set -- copy --destdir="${D}" "$@"
	echo ./setup "$@"
	./setup "$@" || die "setup copy failed"

	# cabal is a bit eager about creating dirs,
	# so remove them if they are empty
	rmdir "${ED}/usr/bin" 2> /dev/null
}

cabal-pkg() {
	# This does not actually register since we're using true instead
	# of ghc-pkg. So it just leaves the .conf file and we can
	# register that ourselves (if it exists).

	if [[ -n ${CABAL_HAS_LIBRARIES} ]]; then
		# Newer cabal can generate a package conf for us:
		./setup register --gen-pkg-config="${T}/${P}.conf"
		ghc-setup-pkg "${T}/${P}.conf"
		ghc-install-pkg
	fi
}

# Some cabal libs are bundled along with some versions of ghc
# eg filepath-1.0 comes with ghc-6.6.1
# by putting CABAL_CORE_LIB_GHC_PV="6.6.1" in an ebuild we are declaring that
# when building with this version of ghc, the ebuild is a dummy that is it will
# install no files since the package is already included with ghc.
# However portage still records the dependency and we can upgrade the package
# to a later one that's not included with ghc.
# You can also put a space separated list, eg CABAL_CORE_LIB_GHC_PV="6.6 6.6.1".
cabal-is-dummy-lib() {
	for version in ${CABAL_CORE_LIB_GHC_PV[*]}; do
		[[ "$(ghc-version)" == ${version} ]] && return 0
	done
	return 1
}

# exported function: check if cabal is correctly installed for
# the currently active ghc (we cannot guarantee this with portage)
haskell-cabal_pkg_setup() {
	if [[ -n ${CABAL_HAS_LIBRARIES} ]]; then
		[[ ${RDEPEND} == *dev-lang/ghc* ]] || eqawarn "QA Notice: A library does not have runtime dependency on dev-lang/ghc."
	fi
	if [[ -z "${CABAL_HAS_BINARIES}" ]] && [[ -z "${CABAL_HAS_LIBRARIES}" ]]; then
		eqawarn "QA Notice: Neither bin nor lib are in CABAL_FEATURES."
	fi
	if [[ -n "${CABAL_UNKNOWN}" ]]; then
		eqawarn "QA Notice: Unknown entry in CABAL_FEATURES: ${CABAL_UNKNOWN}"
	fi
	if cabal-is-dummy-lib; then
		einfo "${P} is included in ghc-${CABAL_CORE_LIB_GHC_PV}, nothing to install."
	fi
}

haskell-cabal_src_configure() {
	cabal-is-dummy-lib && return

	pushd "${S}" > /dev/null

	cabal-bootstrap

	cabal-configure "$@"

	popd > /dev/null
}

# exported function: nice alias
cabal_src_configure() {
	haskell-cabal_src_configure "$@"
}

# exported function: cabal-style bootstrap configure and compile
cabal_src_compile() {
	# it's a common mistake when one bumps ebuild to EAPI="2" (and upper)
	# and forgets to separate src_compile() to src_configure()/src_compile().
	# Such error leads to default src_configure and we lose all passed flags.
	if ! has "${EAPI:-0}" 0 1; then
		local passed_flag
		for passed_flag in "$@"; do
			[[ ${passed_flag} == --flags=* ]] && \
				eqawarn "QA Notice: Cabal option '${passed_flag}' has effect only in src_configure()"
		done
	fi

	cabal-is-dummy-lib && return

	has src_configure ${HASKELL_CABAL_EXPF} || haskell-cabal_src_configure "$@"
	cabal-build

	if [[ -n "${CABAL_USE_HADDOCK}" ]] && use doc; then
		if [[ -n "${CABAL_USE_HSCOLOUR}" ]] && use hscolour; then
			# hscolour and haddock
			cabal-hscolour-haddock
		else
			# just haddock
			cabal-haddock
		fi
	else
		if [[ -n "${CABAL_USE_HSCOLOUR}" ]] && use hscolour; then
			# just hscolour
			cabal-hscolour
		fi
	fi
}

haskell-cabal_src_compile() {
	pushd "${S}" > /dev/null

	cabal_src_compile "$@"

	popd > /dev/null
}

haskell-cabal_src_test() {
	pushd "${S}" > /dev/null

	if cabal-is-dummy-lib; then
		einfo ">>> No tests for dummy library: ${CATEGORY}/${PF}"
	else
		einfo ">>> Test phase [cabal test]: ${CATEGORY}/${PF}"
		set -- test "$@"
		echo ./setup "$@"
		./setup "$@" || die "cabal test failed"
	fi

	popd > /dev/null
}

# exported function: cabal-style copy and register
cabal_src_install() {
	has "${EAPI:-0}" 0 1 2 && ! use prefix && EPREFIX=

	if ! cabal-is-dummy-lib; then
		cabal-copy
		cabal-pkg
	fi

	# create a dummy local package conf file for haskell-updater
	# if it does not exist (dummy libraries and binaries w/o libraries)
	local ghc_confdir_with_prefix="$(ghc-confdir)"
	# remove EPREFIX
	dodir ${ghc_confdir_with_prefix#${EPREFIX}}
	local conf_file="${D}/$(ghc-confdir)/$(ghc-localpkgconf)"
	[[ -e $conf_file ]] || echo '[]' > "$conf_file" || die

	# make sure installed packages do not destroy ghc's
	# bundled packages
	local initial_pkg_db=${ROOT}/$(ghc-libdir)/package.conf.d.initial
	if [[ -e ${initial_pkg_db} ]]; then
		local checked_pkg
		for checked_pkg in $(ghc-listpkg "${conf_file}")
		do
			local initial_pkg
			for initial_pkg in $(ghc-listpkg "${initial_pkg_db}"); do
				if [[ ${checked_pkg} = ${initial_pkg} ]]; then
					eerror "Package ${checked_pkg} is shipped with $(ghc-version)."
					eerror "Ebuild author forgot CABAL_CORE_LIB_GHC_PV entry."
					eerror "Found in ${initial_pkg_db}."
					die
				fi
			done
		done
	fi
}

haskell-cabal_src_install() {
	pushd "${S}" > /dev/null

	cabal_src_install

	popd > /dev/null
}

# @FUNCTION: cabal_flag
# @DESCRIPTION:
# ebuild.sh:use_enable() taken as base
#
# Usage examples:
#
#     CABAL_CONFIGURE_FLAGS=$(cabal_flag gui)
#  leads to "--flags=gui" or "--flags=-gui" (useflag 'gui')
#
#     CABAL_CONFIGURE_FLAGS=$(cabal_flag gtk gui)
#  also leads to "--flags=gui" or " --flags=-gui" (useflag 'gtk')
#
cabal_flag() {
	if [[ -z "$1" ]]; then
		echo "!!! cabal_flag() called without a parameter." >&2
		echo "!!! cabal_flag() <USEFLAG> [<cabal_flagname>]" >&2
		return 1
	fi

	local UWORD=${2:-$1}

	if use "$1"; then
		echo "--flags=${UWORD}"
	else
		echo "--flags=-${UWORD}"
	fi

	return 0
}

# @FUNCTION: cabal_chdeps
# @DESCRIPTION:
# Allows easier patching of $CABAL_FILE (${S}/${PN}.cabal by default)
# depends
#
# Accepts argument list as pairs of substitutions: <from-string> <to-string>...
#
# Dies on error.
#
# Usage examples:
#
# src_prepare() {
#    cabal_chdeps \
#        'base >= 4.2 && < 4.6' 'base >= 4.2 && < 4.7' \
#        'containers ==0.4.*' 'containers >= 0.4 && < 0.6'
#}
# or
# src_prepare() {
#    CABAL_FILE=${S}/${MY_PN}.cabal cabal_chdeps \
#        'base >= 4.2 && < 4.6' 'base >= 4.2 && < 4.7'
#    CABAL_FILE=${S}/${MY_PN}-tools.cabal cabal_chdeps \
#        'base == 3.*' 'base >= 4.2 && < 4.7'
#}
#
cabal_chdeps() {
	local cf=${CABAL_FILE:-${S}/${PN}.cabal}
	local from_ss # ss - substring
	local to_ss
	local orig_c # c - contents
	local new_c

	[[ -f $cf ]] || die "cabal file '$cf' does not exist"

	orig_c=$(< "$cf")

	while :; do
		from_pat=$1
		to_str=$2

		[[ -n ${from_pat} ]] || break
		[[ -n ${to_str} ]] || die "'${from_str}' does not have 'to' part"

		einfo "CHDEP: '${from_pat}' -> '${to_str}'"

		# escape pattern-like symbols
		from_pat=${from_pat//\*/\\*}
		from_pat=${from_pat//\[/\\[}

		new_c=${orig_c//${from_pat}/${to_str}}

		if [[ -n $CABAL_DEBUG_LOOSENING ]]; then
			echo "${orig_c}" >"${T}/${cf}".pre
			echo "${new_c}" >"${T}/${cf}".post
			diff -u "${T}/${cf}".{pre,post}
		fi

		[[ "${orig_c}" == "${new_c}" ]] && die "no trigger for '${from_pat}'"
		orig_c=${new_c}
		shift
		shift
	done

	echo "${new_c}" > "$cf" ||
		die "failed to update"
}

# @FUNCTION: replace-hcflags
# @USAGE: <old> <new>
# @DESCRIPTION:
# Replace the <old> flag with <new> in HCFLAGS. Accepts shell globs for <old>.
# The implementation is picked from flag-o-matic.eclass:replace-flags()
replace-hcflags() {
	[[ $# != 2 ]] && die "Usage: replace-hcflags <old flag> <new flag>"

	local f new=()
	for f in ${HCFLAGS} ; do
		# Note this should work with globs like -O*
		if [[ ${f} == ${1} ]]; then
			einfo "HCFLAGS: replacing '${f}' to '${2}'"
			f=${2}
		fi
		new+=( "${f}" )
	done
	export HCFLAGS="${new[*]}"

	return 0
}