python-single-r1.eclass: Restore PYTHON_SINGLE_TARGET for one impl

Undo the hack that removes PYTHON_SINGLE_TARGET (in favor of plain
PYTHON_TARGETS) when the package supports only one target.  Instead,
output both kinds of flags consistently for all packages, and use IUSE
defaults to enable them when only one interpreter is supported.

This should give similar end results without creating unnecessary
differences between ebuilds with one and multiple implementations.
It will make future API changes easier, as well as simplify tooling
used to detect eclass type.

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

1 files changed, 49 insertions, 94 deletions

diff --git a/eclass/python-single-r1.eclass b/eclass/python-single-r1.eclass
index 47176f79e6ad..7adb136101ad 100644
--- a/eclass/python-single-r1.eclass
+++ b/eclass/python-single-r1.eclass
@@ -179,47 +179,32 @@ EXPORT_FUNCTIONS pkg_setup
 _python_single_set_globals() {
 	_python_set_impls
 
-	local i PYTHON_PKG_DEP
-
 	local flags_mt=( "${_PYTHON_SUPPORTED_IMPLS[@]/#/python_targets_}" )
 	local flags=( "${_PYTHON_SUPPORTED_IMPLS[@]/#/python_single_target_}" )
 	local unflags=( "${_PYTHON_UNSUPPORTED_IMPLS[@]/#/-python_single_target_}" )
 
-	local optflags=${flags_mt[@]/%/(-)?},${unflags[@]/%/(-)}
-
-	IUSE="${flags_mt[*]}"
-
-	local deps requse usedep
 	if [[ ${#_PYTHON_SUPPORTED_IMPLS[@]} -eq 1 ]]; then
-		# There is only one supported implementation; set IUSE and other
-		# variables without PYTHON_SINGLE_TARGET.
-		requse=${flags_mt[*]}
-		python_export "${_PYTHON_SUPPORTED_IMPLS[0]}" PYTHON_PKG_DEP
-		deps="${flags_mt[*]}? ( ${PYTHON_PKG_DEP} ) "
-		# Force on the python_single_target_* flag for this impl, so
-		# that any dependencies that inherit python-single-r1 and
-		# happen to have multiple implementations will still need
-		# to bound by the implementation used by this package.
-		optflags+=,${flags[0]/%/(+)}
+		# if only one implementation is supported, use IUSE defaults
+		# to avoid requesting the user to enable it
+		IUSE="+${flags_mt[0]} +${flags[0]}"
 	else
-		# Multiple supported implementations; honor PYTHON_SINGLE_TARGET.
-		IUSE+=" ${flags[*]}"
-		requse="^^ ( ${flags[*]} )"
-		# Ensure deps honor the same python_single_target_* flag as is set
-		# on this package.
-		optflags+=,${flags[@]/%/(+)?}
-
-		for i in "${_PYTHON_SUPPORTED_IMPLS[@]}"; do
-			# The chosen targets need to be in PYTHON_TARGETS as well.
-			# This is in order to enforce correct dependencies on packages
-			# supporting multiple implementations.
-			requse+=" python_single_target_${i}? ( python_targets_${i} )"
-
-			python_export "${i}" PYTHON_PKG_DEP
-			deps+="python_single_target_${i}? ( ${PYTHON_PKG_DEP} ) "
-		done
+		IUSE="${flags_mt[*]} ${flags[*]}"
 	fi
-	usedep=${optflags// /,}
+
+	local requse="^^ ( ${flags[*]} )"
+	local optflags="${flags_mt[@]/%/(-)?},${unflags[@]/%/(-)},${flags[@]/%/(+)?}"
+	local usedep="${optflags// /,}"
+
+	local deps= i PYTHON_PKG_DEP
+	for i in "${_PYTHON_SUPPORTED_IMPLS[@]}"; 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.
+		requse+=" python_single_target_${i}? ( python_targets_${i} )"
+
+		python_export "${i}" PYTHON_PKG_DEP
+		deps+="python_single_target_${i}? ( ${PYTHON_PKG_DEP} ) "
+	done
 
 	# 1) well, python-exec would suffice as an RDEP
 	# but no point in making this overcomplex, BDEP doesn't hurt anyone
@@ -367,17 +352,11 @@ python_gen_usedep() {
 python_gen_useflags() {
 	debug-print-function ${FUNCNAME} "${@}"
 
-	local flag_prefix impl matches=()
-
-	if [[ ${#_PYTHON_SUPPORTED_IMPLS[@]} -eq 1 ]]; then
-		flag_prefix=python_targets
-	else
-		flag_prefix=python_single_target
-	fi
+	local impl matches=()
 
 	for impl in "${_PYTHON_SUPPORTED_IMPLS[@]}"; do
 		if _python_impl_matches "${impl}" "${@}"; then
-			matches+=( "${flag_prefix}_${impl}" )
+			matches+=( "python_single_target_${impl}" )
 		fi
 	done
 
@@ -419,13 +398,7 @@ python_gen_useflags() {
 python_gen_cond_dep() {
 	debug-print-function ${FUNCNAME} "${@}"
 
-	local flag_prefix impl matches=()
-
-	if [[ ${#_PYTHON_SUPPORTED_IMPLS[@]} -eq 1 ]]; then
-		flag_prefix=python_targets
-	else
-		flag_prefix=python_single_target
-	fi
+	local impl matches=()
 
 	local dep=${1}
 	shift
@@ -440,7 +413,7 @@ python_gen_cond_dep() {
 				dep=${dep//\$\{PYTHON_USEDEP\}/${usedep}}
 			fi
 
-			matches+=( "${flag_prefix}_${impl}? ( ${dep} )" )
+			matches+=( "python_single_target_${impl}? ( ${dep} )" )
 		fi
 	done
 
@@ -484,15 +457,9 @@ python_gen_cond_dep() {
 python_gen_impl_dep() {
 	debug-print-function ${FUNCNAME} "${@}"
 
-	local impl pattern
+	local impl
 	local matches=()
 
-	if [[ ${#_PYTHON_SUPPORTED_IMPLS[@]} -eq 1 ]]; then
-		flag_prefix=python_targets
-	else
-		flag_prefix=python_single_target
-	fi
-
 	local PYTHON_REQ_USE=${1}
 	shift
 
@@ -501,7 +468,7 @@ python_gen_impl_dep() {
 		if _python_impl_matches "${impl}" "${patterns[@]}"; then
 			local PYTHON_PKG_DEP
 			python_export "${impl}" PYTHON_PKG_DEP
-			matches+=( "${flag_prefix}_${impl}? ( ${PYTHON_PKG_DEP} )" )
+			matches+=( "python_single_target_${impl}? ( ${PYTHON_PKG_DEP} )" )
 		fi
 	done
 
@@ -534,47 +501,35 @@ python_setup() {
 		return
 	fi
 
-	if [[ ${#_PYTHON_SUPPORTED_IMPLS[@]} -eq 1 ]]; then
-		if use "python_targets_${_PYTHON_SUPPORTED_IMPLS[0]}"; then
-			# Only one supported implementation, enable it explicitly
-			python_export "${_PYTHON_SUPPORTED_IMPLS[0]}" EPYTHON PYTHON
+	local impl
+	for impl in "${_PYTHON_SUPPORTED_IMPLS[@]}"; do
+		if use "python_single_target_${impl}"; then
+			if [[ ${EPYTHON} ]]; then
+				eerror "Your PYTHON_SINGLE_TARGET setting lists more than a single Python"
+				eerror "implementation. Please set it to just one value. If you need"
+				eerror "to override the value for a single package, please use package.env"
+				eerror "or an equivalent solution (man 5 portage)."
+				echo
+				die "More than one implementation in PYTHON_SINGLE_TARGET."
+			fi
+
+			if ! use "python_targets_${impl}"; then
+				eerror "The implementation chosen as PYTHON_SINGLE_TARGET must be added"
+				eerror "to PYTHON_TARGETS as well. This is in order to ensure that"
+				eerror "dependencies are satisfied correctly. We're sorry"
+				eerror "for the inconvenience."
+				echo
+				die "Build target (${impl}) not in PYTHON_TARGETS."
+			fi
+
+			python_export "${impl}" EPYTHON PYTHON
 			python_wrapper_setup
 		fi
-	else
-		local impl
-		for impl in "${_PYTHON_SUPPORTED_IMPLS[@]}"; do
-			if use "python_single_target_${impl}"; then
-				if [[ ${EPYTHON} ]]; then
-					eerror "Your PYTHON_SINGLE_TARGET setting lists more than a single Python"
-					eerror "implementation. Please set it to just one value. If you need"
-					eerror "to override the value for a single package, please use package.env"
-					eerror "or an equivalent solution (man 5 portage)."
-					echo
-					die "More than one implementation in PYTHON_SINGLE_TARGET."
-				fi
-
-				if ! use "python_targets_${impl}"; then
-					eerror "The implementation chosen as PYTHON_SINGLE_TARGET must be added"
-					eerror "to PYTHON_TARGETS as well. This is in order to ensure that"
-					eerror "dependencies are satisfied correctly. We're sorry"
-					eerror "for the inconvenience."
-					echo
-					die "Build target (${impl}) not in PYTHON_TARGETS."
-				fi
-
-				python_export "${impl}" EPYTHON PYTHON
-				python_wrapper_setup
-			fi
-		done
-	fi
+	done
 
 	if [[ ! ${EPYTHON} ]]; then
 		eerror "No Python implementation selected for the build. Please set"
-		if [[ ${#_PYTHON_SUPPORTED_IMPLS[@]} -eq 1 ]]; then
-			eerror "the PYTHON_TARGETS variable in your make.conf to include one"
-		else
-			eerror "the PYTHON_SINGLE_TARGET variable in your make.conf to one"
-		fi
+		eerror "the PYTHON_SINGLE_TARGET variable in your make.conf to one"
 		eerror "of the following values:"
 		eerror
 		eerror "${_PYTHON_SUPPORTED_IMPLS[@]}"