feat(pipenv): add fallback 3rd party completion loader (#1020)

* feat(pipenv): add fallback 3rd party completion loader

https://pipenv.pypa.io/en/latest/shell/#shell-completion

Co-authored-by: Koichi Murase <[email protected]>

Author: scop

completions/Makefile.am

@@ -316,6 +316,7 @@ bashcomp_DATA = 2to3 \
 		pidof \
 		pine \
 		ping \
+		_pipenv \
 		pkg-config \
 		pkg-get \
 		pkg_delete \

completions/_pipenv

@@ -0,0 +1,15 @@
+# 3rd party completion loader for commands emitting        -*- shell-script -*-
+# their completion using "_${cmdname^^}_COMPLETE=bash_source $cmd".
+# This pattern is used by programs built with https://click.palletsprojects.com
+#
+# This serves as a fallback in case the completion is not installed otherwise.
+
+eval -- "$(
+    # shellcheck disable=SC2154
+    ucname="${cmdname^^}"
+    ucname=${ucname//-/_}
+    export "_${ucname}_COMPLETE=bash_source"
+    "$1" 2>/dev/null
+)"
+
+# ex: filetype=sh

test/fallback/completions/Makefile.am

@@ -24,6 +24,7 @@ EXTRA_DIST = \
 	newgrp \
 	nmcli \
 	nox \
+	pipenv \
 	renice \
 	repomanage \
 	reptyr \

test/fallback/completions/pipenv

@@ -0,0 +1 @@
+../../../completions/_pipenv