python-single-r1.eclass: Revert "Remove deprecated PYTHON_USEDEP..."

Signed-off-by: Michał Górny <mgorny@gentoo.org>

eclass/python-single-r1.eclass

@@ -139,6 +139,29 @@ EXPORT_FUNCTIONS pkg_setup
 # python_single_target_pypy? ( virtual/pypy[gdbm] )
 # @CODE
 
+# @ECLASS-VARIABLE: PYTHON_USEDEP
+# @DESCRIPTION:
+# DEPRECATED.  Use PYTHON_SINGLE_USEDEP or python_gen_cond_dep with
+# PYTHON_MULTI_USEDEP placeholder instead.
+#
+# This is an eclass-generated USE-dependency string which can be used to
+# depend on another Python package being built for the same Python
+# implementations.
+#
+# The generate USE-flag list is compatible with packages using python-r1,
+# python-single-r1 and python-distutils-ng eclasses. It must not be used
+# on packages using python.eclass.
+#
+# Example use:
+# @CODE
+# RDEPEND="dev-python/foo[${PYTHON_USEDEP}]"
+# @CODE
+#
+# Example value:
+# @CODE
+# python_targets_python2_7(-)?,python_single_target_python3_4(+)?
+# @CODE
+
 # @ECLASS-VARIABLE: PYTHON_SINGLE_USEDEP
 # @DESCRIPTION:
 # This is an eclass-generated USE-dependency string which can be used to
@@ -203,6 +226,7 @@ _python_single_set_globals() {
 
 	local flags_mt=( "${_PYTHON_SUPPORTED_IMPLS[@]/#/python_targets_}" )
 	local flags=( "${_PYTHON_SUPPORTED_IMPLS[@]/#/python_single_target_}" )
+	local unflags=( "${_PYTHON_UNSUPPORTED_IMPLS[@]/#/-python_single_target_}" )
 
 	if [[ ${#_PYTHON_SUPPORTED_IMPLS[@]} -eq 1 ]]; then
 		# if only one implementation is supported, use IUSE defaults
@@ -213,6 +237,8 @@ _python_single_set_globals() {
 	fi
 
 	local requse="^^ ( ${flags[*]} )"
+	local optflags="${flags_mt[@]/%/(-)?},${unflags[@]/%/(-)},${flags[@]/%/(+)?}"
+	local usedep="${optflags// /,}"
 	local single_flags="${flags[@]/%/(-)?}"
 	local single_usedep=${single_flags// /,}
 
@@ -250,6 +276,13 @@ _python_single_set_globals() {
 			die "PYTHON_REQUIRED_USE integrity check failed"
 		fi
 
+		if [[ ${PYTHON_USEDEP} != "${usedep}" ]]; then
+			eerror "PYTHON_USEDEP have changed between inherits!"
+			eerror "Before: ${PYTHON_USEDEP}"
+			eerror "Now   : ${usedep}"
+			die "PYTHON_USEDEP integrity check failed"
+		fi
+
 		if [[ ${PYTHON_SINGLE_USEDEP} != "${single_usedep}" ]]; then
 			eerror "PYTHON_SINGLE_USEDEP have changed between inherits!"
 			eerror "Before: ${PYTHON_SINGLE_USEDEP}"
@@ -259,8 +292,10 @@ _python_single_set_globals() {
 	else
 		PYTHON_DEPS=${deps}
 		PYTHON_REQUIRED_USE=${requse}
+		PYTHON_USEDEP=${usedep}
 		PYTHON_SINGLE_USEDEP=${single_usedep}
-		readonly PYTHON_DEPS PYTHON_REQUIRED_USE PYTHON_SINGLE_USEDEP
+		readonly PYTHON_DEPS PYTHON_REQUIRED_USE PYTHON_USEDEP \
+			PYTHON_SINGLE_USEDEP
 	fi
 }
 _python_single_set_globals
@@ -270,36 +305,92 @@ if [[ ! ${_PYTHON_SINGLE_R1} ]]; then
 
 # @FUNCTION: _python_gen_usedep
 # @INTERNAL
-# @USAGE: [<pattern>...]
+# @USAGE: <-s|-u> [<pattern>...]
 # @DESCRIPTION:
 # Output a USE dependency string for Python implementations which
 # are both in PYTHON_COMPAT and match any of the patterns passed
 # as parameters to the function.
 #
+# The first argument specifies USE-dependency type: '-s' for new-style
+# PYTHON_SINGLE_USEDEP, '-u' for backwards-compatible PYTHON_USEDEP.
+#
+# The patterns can be either fnmatch-style patterns (matched via bash
+# == operator against PYTHON_COMPAT values) or '-2' / '-3' to indicate
+# appropriately all enabled Python 2/3 implementations (alike
+# python_is_python3). Remember to escape or quote the fnmatch patterns
+# to prevent accidental shell filename expansion.
+#
+# This is an internal function used to implement python_gen_cond_dep
+# and deprecated python_gen_usedep.
+_python_gen_usedep() {
+	debug-print-function ${FUNCNAME} "${@}"
+
+	local mode=${1}
+	shift
+	local impl matches=()
+
+	for impl in "${_PYTHON_SUPPORTED_IMPLS[@]}"; do
+		if _python_impl_matches "${impl}" "${@}"; then
+			case ${mode} in
+				-s)
+					matches+=(
+						"python_single_target_${impl}(-)?"
+					)
+					;;
+				-u)
+					matches+=(
+						"python_targets_${impl}(-)?"
+						"python_single_target_${impl}(+)?"
+					)
+				;;
+			esac
+		fi
+	done
+
+	[[ ${matches[@]} ]] || die "No supported implementations match python_gen_usedep patterns: ${@}"
+
+	local out=${matches[@]}
+	echo "${out// /,}"
+}
+
+# @FUNCTION: python_gen_usedep
+# @USAGE: <pattern> [...]
+# @DESCRIPTION:
+# DEPRECATED.  Please use python_gen_cond_dep instead.
+#
+# Output a USE dependency string for Python implementations which
+# are both in PYTHON_COMPAT and match any of the patterns passed
+# as parameters to the function.
+#
 # The patterns can be either fnmatch-style patterns (matched via bash
 # == operator against PYTHON_COMPAT values) or '-2' / '-3' to indicate
 # appropriately all enabled Python 2/3 implementations (alike
 # python_is_python3). Remember to escape or quote the fnmatch patterns
 # to prevent accidental shell filename expansion.
 #
-# This is an internal function used to implement python_gen_cond_dep.
-_python_gen_usedep() {
+# When all implementations are requested, please use ${PYTHON_USEDEP}
+# instead. Please also remember to set an appropriate REQUIRED_USE
+# to avoid ineffective USE flags.
+#
+# Example:
+# @CODE
+# PYTHON_COMPAT=( python{2_7,3_4} )
+# DEPEND="doc? ( dev-python/epydoc[$(python_gen_usedep 'python2*')] )"
+# @CODE
+#
+# It will cause the dependency to look like:
+# @CODE
+# DEPEND="doc? ( dev-python/epydoc[python_targets_python2_7(-)?,...] )"
+# @CODE
+python_gen_usedep() {
 	debug-print-function ${FUNCNAME} "${@}"
 
-	local impl matches=()
-
-	for impl in "${_PYTHON_SUPPORTED_IMPLS[@]}"; do
-		if _python_impl_matches "${impl}" "${@}"; then
-			matches+=(
-				"python_single_target_${impl}(-)?"
-			)
-		fi
-	done
-
-	[[ ${matches[@]} ]] || die "No supported implementations match python_gen_usedep patterns: ${@}"
-
-	local out=${matches[@]}
-	echo "${out// /,}"
+	# output only once, during some reasonable phase
+	# (avoid spamming cache regen runs)
+	if [[ ${EBUILD_PHASE} == setup ]]; then
+		eqawarn "python_gen_usedep() is deprecated. Please use python_gen_cond_dep instead."
+	fi
+	_python_gen_usedep -u "${@}"
 }
 
 # @FUNCTION: python_gen_useflags
@@ -353,9 +444,10 @@ python_gen_useflags() {
 # to prevent accidental shell filename expansion.
 #
 # In order to enforce USE constraints on the packages, verbatim
-# '${PYTHON_SINGLE_USEDEP}' and '${PYTHON_MULTI_USEDEP}' (quoted!) may
-# be placed in the dependency specification. It will get expanded within
-# the function into a proper USE dependency string.
+# '${PYTHON_USEDEP}', '${PYTHON_SINGLE_USEDEP}'
+# and '${PYTHON_MULTI_USEDEP}' (quoted!) may be placed in the dependency
+# specification. It will get expanded within the function into a proper
+# USE dependency string.
 #
 # Example:
 # @CODE
@@ -381,11 +473,15 @@ python_gen_cond_dep() {
 
 	for impl in "${_PYTHON_SUPPORTED_IMPLS[@]}"; do
 		if _python_impl_matches "${impl}" "${@}"; then
-			# substitute ${PYTHON_SINGLE_USEDEP} if used
-			# (since python_gen_usedep() will not return
-			#  ${PYTHON_SINGLE_USEDEP}, the code is run at most once)
+			# substitute ${PYTHON_USEDEP} if used
+			# (since python_gen_usedep() will not return ${PYTHON_USEDEP}
+			#  the code is run at most once)
+			if [[ ${dep} == *'${PYTHON_USEDEP}'* ]]; then
+				local usedep=$(_python_gen_usedep -u "${@}")
+				dep=${dep//\$\{PYTHON_USEDEP\}/${usedep}}
+			fi
 			if [[ ${dep} == *'${PYTHON_SINGLE_USEDEP}'* ]]; then
-				local usedep=$(_python_gen_usedep "${@}")
+				local usedep=$(_python_gen_usedep -s "${@}")
 				dep=${dep//\$\{PYTHON_SINGLE_USEDEP\}/${usedep}}
 			fi
 			local multi_usedep="python_targets_${impl}(-)"