ltprune.eclass: Split prune_libtool_files out of eutils

Move the prune_libtool_files into a dedicated ltprune.eclass.
The function is quite complex and depends on toolchain-funcs. It has
a separate maintainer, is not useful to non-autotools ebuilds, and even
there it is frequently replaced by the simpler 'find ... -delete' call.

The new eclass is implicitly inherited by eutils in EAPI 6 and older
in order to preserve compatibility with existing ebuilds. However, all
ebuilds should switch to inheriting it directly.

The split has been suggested by Ulrich Müller.

1 files changed, 167 insertions, 0 deletions

diff --git a/eclass/ltprune.eclass b/eclass/ltprune.eclass
new file mode 100644
index 000000000000..6b3e93921d96
--- /dev/null
+++ b/eclass/ltprune.eclass
@@ -0,0 +1,167 @@
+# Copyright 1999-2017 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: ltprune.eclass
+# @MAINTAINER:
+# Michał Górny <mgorny@gentoo.org>
+# @BLURB: Smart .la file pruning
+# @DESCRIPTION:
+# A function to locate and remove unnecessary .la files.
+#
+# Discouraged. Whenever possible, please use much simpler:
+# @CODE
+# find "${D}" -name '*.la' -delete || die
+# @CODE
+
+if [[ -z ${_LTPRUNE_ECLASS} ]]; then
+
+inherit toolchain-funcs
+
+# @FUNCTION: prune_libtool_files
+# @USAGE: [--all|--modules]
+# @DESCRIPTION:
+# Locate unnecessary libtool files (.la) and libtool static archives
+# (.a) and remove them from installation image.
+#
+# By default, .la files are removed whenever the static linkage can
+# either be performed using pkg-config or doesn't introduce additional
+# flags.
+#
+# If '--modules' argument is passed, .la files for modules (plugins) are
+# removed as well. This is usually useful when the package installs
+# plugins and the plugin loader does not use .la files.
+#
+# If '--all' argument is passed, all .la files are removed without
+# performing any heuristic on them. You shouldn't ever use that,
+# and instead report a bug in the algorithm instead.
+#
+# The .a files are only removed whenever corresponding .la files state
+# that they should not be linked to, i.e. whenever these files
+# correspond to plugins.
+#
+# Note: if your package installs both static libraries and .pc files
+# which use variable substitution for -l flags, you need to add
+# pkg-config to your DEPEND.
+prune_libtool_files() {
+	debug-print-function ${FUNCNAME} "$@"
+
+	local removing_all removing_modules opt
+	for opt; do
+		case "${opt}" in
+			--all)
+				removing_all=1
+				removing_modules=1
+				;;
+			--modules)
+				removing_modules=1
+				;;
+			*)
+				die "Invalid argument to ${FUNCNAME}(): ${opt}"
+		esac
+	done
+
+	local f
+	local queue=()
+	while IFS= read -r -d '' f; do # for all .la files
+		local archivefile=${f/%.la/.a}
+
+		# The following check is done by libtool itself.
+		# It helps us avoid removing random files which match '*.la',
+		# see bug #468380.
+		if ! sed -n -e '/^# Generated by .*libtool/q0;4q1' "${f}"; then
+			continue
+		fi
+
+		[[ ${f} != ${archivefile} ]] || die 'regex sanity check failed'
+		local reason= pkgconfig_scanned=
+		local snotlink=$(sed -n -e 's:^shouldnotlink=::p' "${f}")
+
+		if [[ ${snotlink} == yes ]]; then
+
+			# Remove static libs we're not supposed to link against.
+			if [[ -f ${archivefile} ]]; then
+				einfo "Removing unnecessary ${archivefile#${D%/}} (static plugin)"
+				queue+=( "${archivefile}" )
+			fi
+
+			# The .la file may be used by a module loader, so avoid removing it
+			# unless explicitly requested.
+			if [[ ${removing_modules} ]]; then
+				reason='module'
+			fi
+
+		else
+
+			# Remove .la files when:
+			# - user explicitly wants us to remove all .la files,
+			# - respective static archive doesn't exist,
+			# - they are covered by a .pc file already,
+			# - they don't provide any new information (no libs & no flags).
+
+			if [[ ${removing_all} ]]; then
+				reason='requested'
+			elif [[ ! -f ${archivefile} ]]; then
+				reason='no static archive'
+			elif [[ ! $(sed -nre \
+					"s/^(dependency_libs|inherited_linker_flags)='(.*)'$/\2/p" \
+					"${f}") ]]; then
+				reason='no libs & flags'
+			else
+				if [[ ! ${pkgconfig_scanned} ]]; then
+					# Create a list of all .pc-covered libs.
+					local pc_libs=()
+					if [[ ! ${removing_all} ]]; then
+						local pc
+						local tf=${T}/prune-lt-files.pc
+						local pkgconf=$(tc-getPKG_CONFIG)
+
+						while IFS= read -r -d '' pc; do # for all .pc files
+							local arg libs
+
+							# Use pkg-config if available (and works),
+							# fallback to sed.
+							if ${pkgconf} --exists "${pc}" &>/dev/null; then
+								sed -e '/^Requires:/d' "${pc}" > "${tf}"
+								libs=$(${pkgconf} --libs "${tf}")
+							else
+								libs=$(sed -ne 's/^Libs://p' "${pc}")
+							fi
+
+							for arg in ${libs}; do
+								if [[ ${arg} == -l* ]]; then
+									if [[ ${arg} == '*$*' ]]; then
+										eerror "${FUNCNAME}: variable substitution likely failed in ${pc}"
+										eerror "(arg: ${arg})"
+										eerror "Most likely, you need to add virtual/pkgconfig to DEPEND."
+										die "${FUNCNAME}: unsubstituted variable found in .pc"
+									fi
+
+									pc_libs+=( lib${arg#-l}.la )
+								fi
+							done
+						done < <(find "${D}" -type f -name '*.pc' -print0)
+
+						rm -f "${tf}"
+					fi
+
+					pkgconfig_scanned=1
+				fi # pkgconfig_scanned
+
+				has "${f##*/}" "${pc_libs[@]}" && reason='covered by .pc'
+			fi # removal due to .pc
+
+		fi # shouldnotlink==no
+
+		if [[ ${reason} ]]; then
+			einfo "Removing unnecessary ${f#${D%/}} (${reason})"
+			queue+=( "${f}" )
+		fi
+	done < <(find "${D}" -xtype f -name '*.la' -print0)
+
+	if [[ ${queue[@]} ]]; then
+		rm -f "${queue[@]}"
+	fi
+}
+
+_LTPRUNE_ECLASS=1
+fi #_LTPRUNE_ECLASS