refactor(tar): turn basic_tar into a boolean variable

Author: akinomyoga

completions/tar

@@ -276,7 +276,7 @@ __tar_complete_mode()
         filler i
 
     short_modes="ctx"
-    [[ ! $basic_tar ]] && short_modes="ctxurdA"
+    ! "$basic_tar" && short_modes="ctxurdA"
 
     # Remove prefix when needed
     rawopt=${cur#-}
@@ -289,7 +289,7 @@ __tar_complete_mode()
 
         # when user passed something like 'tar cf' do not put the '-' before
         filler=
-        if [[ ! $cur && ! $basic_tar ]]; then
+        if [[ ! $cur ]] && ! "$basic_tar"; then
             filler=-
         fi
 
@@ -357,14 +357,14 @@ __tar_try_mode()
     case "$cur" in
         --*)
             # posix tar does not support long opts
-            [[ $basic_tar ]] && return 0
+            "$basic_tar" && return 0
             __gtar_complete_lopts
             return $?
             ;;
 
         -*)
             # posix tar does not support short options
-            [[ $basic_tar ]] && return 0
+            "$basic_tar" && return 0
 
             __tar_complete_mode && return 0
             ;;
@@ -485,7 +485,7 @@ __tar_detect_ext()
 
 _gtar()
 {
-    local long_opts short_opts basic_tar="" \
+    local long_opts short_opts basic_tar=false \
         long_arg_none="" long_arg_opt="" long_arg_req="" \
         short_arg_none="" short_arg_opt="" short_arg_req="" \
         tar_mode tar_mode_arg old_opt_progress=0 \
@@ -675,7 +675,7 @@ __tar_posix_prev_handle()
 
 _posix_tar()
 {
-    local long_opts short_opts basic_tar="" \
+    local long_opts short_opts basic_tar=true \
         long_arg_none="" long_arg_opt long_arg_req="" \
         short_arg_none short_arg_opt short_arg_req \
         tar_mode tar_mode_arg old_opt_progress=0 \
@@ -691,7 +691,6 @@ _posix_tar()
 
     _comp_initialize -s -- "$@" || return
 
-    basic_tar=yes
     tar_mode=none
 
     # relatively compatible modes are {c,t,x}