[gentoo-python] [PATCH] Validate PYTHON_COMPAT, support disabling implementations.

["Michał Górny" <mgorny@gentoo.org>]

Now eclasses die with invalid implementations in PYTHON_COMPAT (well,
except for python-any-r1 which barely looks at PYTHON_COMPAT and more
relies on _PYTHON_ALL_IMPLS) and can omit the implementations which will
be marked as 'removed' (for upcoming pypy1.8 cleanup).
---
 gx86/eclass/python-any-r1.eclass    | 11 ++++-----
 gx86/eclass/python-r1.eclass        | 49 +++++++++++++++++++++++++++++--------
 gx86/eclass/python-single-r1.eclass | 39 +++++++++++++++++++----------
 gx86/eclass/python-utils-r1.eclass  | 31 +++++++++++++++++++++++
 4 files changed, 101 insertions(+), 29 deletions(-)

diff --git a/gx86/eclass/python-any-r1.eclass b/gx86/eclass/python-any-r1.eclass
index 199602a..492ab27 100644
--- a/gx86/eclass/python-any-r1.eclass
+++ b/gx86/eclass/python-any-r1.eclass
@@ -134,13 +134,13 @@ _python_build_set_globals() {
 }
 _python_build_set_globals
 
-# @FUNCTION: _python_impl_supported
+# @FUNCTION: _python_EPYTHON_supported
 # @USAGE: <epython>
 # @INTERNAL
 # @DESCRIPTION:
 # Check whether the specified implementation is supported by package
 # (specified in PYTHON_COMPAT).
-_python_impl_supported() {
+_python_EPYTHON_supported() {
 	debug-print-function ${FUNCNAME} "${@}"
 
 	local i=${1/./_}
@@ -153,6 +153,7 @@ _python_impl_supported() {
 			;;
 		*)
 			ewarn "Invalid EPYTHON: ${EPYTHON}"
+			return 1
 			;;
 	esac
 
@@ -173,7 +174,7 @@ python-any-r1_pkg_setup() {
 
 	# first, try ${EPYTHON}... maybe it's good enough for us.
 	if [[ ${EPYTHON} ]]; then
-		if _python_impl_supported "${EPYTHON}"; then
+		if _python_EPYTHON_supported "${EPYTHON}"; then
 			python_export EPYTHON PYTHON
 			return
 		fi
@@ -187,7 +188,7 @@ python-any-r1_pkg_setup() {
 		if [[ ! ${i} ]]; then
 			# no eselect-python?
 			break
-		elif _python_impl_supported "${i}"; then
+		elif _python_EPYTHON_supported "${i}"; then
 			python_export "${i}" EPYTHON PYTHON
 			return
 		fi
@@ -206,8 +207,6 @@ python-any-r1_pkg_setup() {
 		python_export "${i}" PYTHON_PKG_DEP EPYTHON PYTHON
 		ROOT=/ has_version "${PYTHON_PKG_DEP}" && return
 	done
-
-	die $EPYTHON
 }
 
 _PYTHON_ANY_R1=1
diff --git a/gx86/eclass/python-r1.eclass b/gx86/eclass/python-r1.eclass
index 8557727..5067931 100644
--- a/gx86/eclass/python-r1.eclass
+++ b/gx86/eclass/python-r1.eclass
@@ -132,7 +132,23 @@ fi
 # @CODE
 
 _python_set_globals() {
-	local flags=( "${PYTHON_COMPAT[@]/#/python_targets_}" )
+	local impls=() PYTHON_DEPS=
+
+	local i PYTHON_PKG_DEP
+	for i in "${PYTHON_COMPAT[@]}"; do
+		_python_impl_supported "${i}" || continue
+
+		python_export "${i}" PYTHON_PKG_DEP
+		PYTHON_DEPS+="python_targets_${i}? ( ${PYTHON_PKG_DEP} ) "
+
+		impls+=( "${i}" )
+	done
+
+	if [[ ${#impls[@]} -eq 0 ]]; then
+		die "No supported implementation in PYTHON_COMPAT."
+	fi
+
+	local flags=( "${impls[@]/#/python_targets_}" )
 	local optflags=${flags[@]/%/?}
 
 	# A nice QA trick here. Since a python-single-r1 package has to have
@@ -141,7 +157,7 @@ _python_set_globals() {
 	# it should prevent developers from mistakenly depending on packages
 	# not supporting multiple Python implementations.
 
-	local flags_st=( "${PYTHON_COMPAT[@]/#/-python_single_target_}" )
+	local flags_st=( "${impls[@]/#/-python_single_target_}" )
 	optflags+=,${flags_st[@]/%/(-)}
 
 	IUSE=${flags[*]}
@@ -152,12 +168,7 @@ _python_set_globals() {
 	# but no point in making this overcomplex, BDEP doesn't hurt anyone
 	# 2) python-exec should be built with all targets forced anyway
 	# but if new targets were added, we may need to force a rebuild
-	PYTHON_DEPS="dev-python/python-exec[${PYTHON_USEDEP}]"
-	local i PYTHON_PKG_DEP
-	for i in "${PYTHON_COMPAT[@]}"; do
-		python_export "${i}" PYTHON_PKG_DEP
-		PYTHON_DEPS+=" python_targets_${i}? ( ${PYTHON_PKG_DEP} )"
-	done
+	PYTHON_DEPS+="dev-python/python-exec[${PYTHON_USEDEP}]"
 }
 _python_set_globals
 
@@ -171,6 +182,8 @@ _python_validate_useflags() {
 	local i
 
 	for i in "${PYTHON_COMPAT[@]}"; do
+		_python_impl_supported "${i}" || continue
+
 		use "python_targets_${i}" && return 0
 	done
 
@@ -210,6 +223,8 @@ python_gen_usedep() {
 	local matches=()
 
 	for impl in "${PYTHON_COMPAT[@]}"; do
+		_python_impl_supported "${impl}" || continue
+
 		for pattern; do
 			if [[ ${impl} == ${pattern} ]]; then
 				matches+=(
@@ -249,6 +264,8 @@ python_gen_useflags() {
 	local matches=()
 
 	for impl in "${PYTHON_COMPAT[@]}"; do
+		_python_impl_supported "${impl}" || continue
+
 		for pattern; do
 			if [[ ${impl} == ${pattern} ]]; then
 				matches+=( "python_targets_${impl}" )
@@ -292,6 +309,8 @@ python_gen_cond_dep() {
 	shift
 
 	for impl in "${PYTHON_COMPAT[@]}"; do
+		_python_impl_supported "${impl}" || continue
+
 		for pattern; do
 			if [[ ${impl} == ${pattern} ]]; then
 				matches+=( "python_targets_${impl}? ( ${dep} )" )
@@ -337,6 +356,8 @@ python_copy_sources() {
 	einfo "Will copy sources from ${S}"
 	# the order is irrelevant here
 	for impl in "${PYTHON_COMPAT[@]}"; do
+		_python_impl_supported "${impl}" || continue
+
 		if use "python_targets_${impl}"
 		then
 			local BUILD_DIR=${bdir%%/}-${impl}
@@ -369,6 +390,8 @@ _python_check_USE_PYTHON() {
 
 			local impl py2 py3 dis_py2 dis_py3
 			for impl in "${PYTHON_COMPAT[@]}"; do
+				_python_impl_supported "${impl}" || continue
+
 				if use "python_targets_${impl}"; then
 					case "${impl}" in
 						python2_*)
@@ -480,6 +503,8 @@ _python_check_USE_PYTHON() {
 		local impl old=${USE_PYTHON} new=() removed=()
 
 		for impl in "${PYTHON_COMPAT[@]}"; do
+			_python_impl_supported "${impl}" || continue
+
 			local abi
 			case "${impl}" in
 				python*)
@@ -573,7 +598,9 @@ python_foreach_impl() {
 
 	debug-print "${FUNCNAME}: bdir = ${bdir}"
 	for impl in "${_PYTHON_ALL_IMPLS[@]}"; do
-		if has "${impl}" "${PYTHON_COMPAT[@]}" && use "python_targets_${impl}"
+		if has "${impl}" "${PYTHON_COMPAT[@]}" \
+			&& _python_impl_supported "${impl}" \
+			&& use "python_targets_${impl}"
 		then
 			local EPYTHON PYTHON
 			python_export "${impl}" EPYTHON PYTHON
@@ -601,7 +628,9 @@ python_export_best() {
 
 	local impl best
 	for impl in "${_PYTHON_ALL_IMPLS[@]}"; do
-		if has "${impl}" "${PYTHON_COMPAT[@]}" && use "python_targets_${impl}"
+		if has "${impl}" "${PYTHON_COMPAT[@]}" \
+			&& _python_impl_supported "${impl}" \
+			&& use "python_targets_${impl}"
 		then
 			best=${impl}
 		fi
diff --git a/gx86/eclass/python-single-r1.eclass b/gx86/eclass/python-single-r1.eclass
index fe26251..774f43e 100644
--- a/gx86/eclass/python-single-r1.eclass
+++ b/gx86/eclass/python-single-r1.eclass
@@ -134,8 +134,31 @@ fi
 # @CODE
 
 _python_single_set_globals() {
-	local flags_mt=( "${PYTHON_COMPAT[@]/#/python_targets_}" )
-	local flags=( "${PYTHON_COMPAT[@]/#/python_single_target_}" )
+	local impls=()
+
+	PYTHON_DEPS=
+	local i PYTHON_PKG_DEP
+	for i in "${PYTHON_COMPAT[@]}"; do
+		_python_impl_supported "${i}" || continue
+
+		# The chosen targets need to be in PYTHON_TARGETS as well.
+		# This is in order to enforce correct dependencies on packages
+		# supporting multiple implementations.
+		#REQUIRED_USE+=" python_single_target_${i}? ( python_targets_${i} )"
+
+		python_export "${i}" PYTHON_PKG_DEP
+		PYTHON_DEPS+="python_single_target_${i}? ( ${PYTHON_PKG_DEP} ) "
+
+		impls+=( "${i}" )
+	done
+
+	if [[ ${#impls[@]} -eq 0 ]]; then
+		die "No supported implementation in PYTHON_COMPAT."
+	fi
+
+	local flags_mt=( "${impls[@]/#/python_targets_}" )
+	local flags=( "${impls[@]/#/python_single_target_}" )
+
 	local optflags=${flags_mt[@]/%/?}
 	optflags+=,${flags[@]/%/(+)?}
 
@@ -147,17 +170,7 @@ _python_single_set_globals() {
 	# but no point in making this overcomplex, BDEP doesn't hurt anyone
 	# 2) python-exec should be built with all targets forced anyway
 	# but if new targets were added, we may need to force a rebuild
-	PYTHON_DEPS="dev-python/python-exec[${PYTHON_USEDEP}]"
-	local i PYTHON_PKG_DEP
-	for i in "${PYTHON_COMPAT[@]}"; do
-		# The chosen targets need to be in PYTHON_TARGETS as well.
-		# This is in order to enforce correct dependencies on packages
-		# supporting multiple implementations.
-		#REQUIRED_USE+=" python_single_target_${i}? ( python_targets_${i} )"
-
-		python_export "${i}" PYTHON_PKG_DEP
-		PYTHON_DEPS+=" python_single_target_${i}? ( ${PYTHON_PKG_DEP} )"
-	done
+	PYTHON_DEPS+="dev-python/python-exec[${PYTHON_USEDEP}]"
 }
 _python_single_set_globals
 
diff --git a/gx86/eclass/python-utils-r1.eclass b/gx86/eclass/python-utils-r1.eclass
index ba270b5..ab72225 100644
--- a/gx86/eclass/python-utils-r1.eclass
+++ b/gx86/eclass/python-utils-r1.eclass
@@ -47,6 +47,37 @@ _PYTHON_ALL_IMPLS=(
 	python2_5 python2_6 python2_7
 )
 
+# @FUNCTION: _python_impl_supported
+# @USAGE: <impl>
+# @INTERNAL
+# @DESCRIPTION:
+# Check whether the implementation <impl> (PYTHON_COMPAT-form)
+# is still supported.
+#
+# Returns 0 if the implementation is valid and supported. If it is
+# unsupported, returns 1 -- and the caller should ignore the entry.
+# If it is invalid, dies with an appopriate error messages.
+_python_impl_supported() {
+	debug-print-function ${FUNCNAME} "${@}"
+
+	[[ ${#} -eq 1 ]] || die "${FUNCNAME}: takes exactly 1 argument (impl)."
+
+	local impl=${1}
+
+	# keep in sync with _PYTHON_ALL_IMPLS!
+	# (not using that list because inline patterns shall be faster)
+	case "${impl}" in
+		python2_[567]|python3_[123]|pypy1_[89]|pypy2_0|jython2_5)
+			return 0
+			;;
+#		pypy1_8)
+#			return 1
+#			;;
+		*)
+			die "Invalid implementation in PYTHON_COMPAT: ${impl}"
+	esac
+}
+
 # @ECLASS-VARIABLE: PYTHON
 # @DESCRIPTION:
 # The absolute path to the current Python interpreter.
-- 
1.8.1