Add support for tar zstd completion (bug #913949)

This patch adds support for completing tar commands with zstd
compression extensions (`.zst' and `.tzst').  Support for the
compression itself is available since tar-1.30+dfsg-3 [1].

Thanks to Adam Borowski for reporting.

[1] https://tracker.debian.org/news/1003756/accepted-tar-130dfsg-3-source-amd64-into-unstable/

3 files changed, 59 insertions, 0 deletions

diff --git a/debian/changelog b/debian/changelog
index 2c0fd9ea..3ab99c54 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -2,6 +2,7 @@ bash-completion (1:2.8-4) UNRELEASED; urgency=medium
 
   * Allow `+' in (ssh/know_hosts) hostnames.  (Closes: #848125)
   * Add completions for OpenRC rc-service.  (Closes: #865548)
+  * Add zstd completions for tar.  (Closes: #913949)
 
  -- Gabriel F. T. Gomes <gabriel@inconstante.eti.br>  Sat, 10 Nov 2018 18:07:37 -0200
 
diff --git a/debian/patches/12-tar-support-completions-for-zstd-compression.patch b/debian/patches/12-tar-support-completions-for-zstd-compression.patch
new file mode 100644
index 00000000..d5055bc4
--- /dev/null
+++ b/debian/patches/12-tar-support-completions-for-zstd-compression.patch
@@ -0,0 +1,57 @@
+From: Gabriel F. T. Gomes <gabriel@inconstante.eti.br>
+Subject: tar: Support completions for zstd compression extensions
+Origin: vendor, https://bugs.debian.org/913949
+Bug-Debian: https://bugs.debian.org/913949
+Forwarded: yes, https://github.com/scop/bash-completion/pull/255
+
+Since upstream version 1.30.90, GNU tar supports zstd compression [1].
+According to the same NEWS entry, the extensions for archive names are
+`.zst' and `.tzst'.  This patch adds support for completing these
+extensions.
+
+This is the output of the completions after the patch:
+
+  $ ls
+  bla.gem.gz   bla.invalid.gz   bla.spkg.gz   bla.tar.gz   bla.tgz
+  bla.gem.zst  bla.invalid.zst  bla.spkg.zst  bla.tar.zst  bla.tzst
+  $ tar -tf bla.
+  bla.gem.gz    bla.spkg.gz   bla.tar.gz    bla.tgz
+  bla.gem.zst   bla.spkg.zst  bla.tar.zst   bla.tzst
+  $ tar -ztf bla.
+  bla.gem.gz   bla.spkg.gz  bla.tar.gz   bla.tgz
+
+Since tar does not provide a one-character shortcut for zstd
+compression, I wasn't able to filter only .zst files:
+
+  $ tar --zstd -tf bla.[TAB]
+  bla.gem.gz    bla.spkg.gz   bla.tar.gz    bla.tgz
+  bla.gem.zst   bla.spkg.zst  bla.tar.zst   bla.tzst
+
+The request came from Adam Borowski via a Debian bug [2].
+
+[1] http://git.savannah.gnu.org/cgit/tar.git/commit/NEWS?id=688924d2a8e1cefb2a5c6c5e562391b5bcfadcb2
+
+[2] https://bugs.debian.org/913949
+---
+ completions/tar | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/completions/tar b/completions/tar
+index 49265ad4..4f20d2e2 100644
+--- a/completions/tar
++++ b/completions/tar
+@@ -433,9 +433,9 @@ __tar_cleanup_prev()
+ 
+ __tar_detect_ext()
+ {
+-    local tars='@(@(tar|gem|spkg)?(.@(Z|[bgx]z|bz2|lz?(ma|o)))|t@([abglx]z|b?(z)2))'
++    local tars='@(@(tar|gem|spkg)?(.@(Z|[bgx]z|bz2|lz?(ma|o)|zst))|t@([abglx]z|b?(z)2|zst))'
+     ext="$tars"
+-    regex='\(\(tar\|gem\|spkg\)\(\.\(Z\|[bgx]z\|bz2\|lz\(ma\|o\)\?\)\)\?\|t\([abglx]z\|bz\?2\)\)'
++    regex='\(\(tar\|gem\|spkg\)\(\.\(Z\|[bgx]z\|bz2\|lz\(ma\|o\)\?\|zst\)\)\?\|t\([abglx]z\|bz\?2\)\)'
+ 
+     case "$tar_mode_arg" in
+         --*)
+-- 
+2.19.1
+
diff --git a/debian/patches/series b/debian/patches/series
index e9884590..3717b5f7 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -10,4 +10,5 @@
 09-backport-to-fix-wildcard-completion.patch
 10-reimplement-known-hosts-file-parsing.patch
 11-add-completions-for-openrc-rc-service.patch
+12-tar-support-completions-for-zstd-compression.patch
 99-use-install-data-hook.patch