From c0d835764fbf33b2effc359498e58e8a114444a8 Mon Sep 17 00:00:00 2001
From: Jan Edmund Lazo <janedmundlazo@hotmail.com>
Date: Tue, 2 Oct 2018 22:10:47 -0400
Subject: [PATCH] vim-patch:8.1.0047: no completion for :unlet $VAR

Problem:    No completion for :unlet $VAR.
Solution:   Add completion. (Jason Franklin)
https://github.com/vim/vim/commit/19834010889fc5bfa0f88b3ba83133dae6c0a35d
---
 src/nvim/ex_docmd.c             | 13 +++++++++++--
 src/nvim/testdir/test_unlet.vim | 10 ++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index f8d4e7d980..2a733f5831 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -3260,8 +3260,15 @@ const char * set_one_cmd_context(
     while ((xp->xp_pattern = (char_u *)strchr(arg, ' ')) != NULL) {
       arg = (const char *)xp->xp_pattern + 1;
     }
+
     xp->xp_context = EXPAND_USER_VARS;
     xp->xp_pattern = (char_u *)arg;
+
+    if (*xp->xp_pattern == '$') {
+      xp->xp_context = EXPAND_ENV_VARS;
+      xp->xp_pattern++;
+    }
+
     break;
 
   case CMD_function:
@@ -9049,8 +9056,10 @@ makeopens(
     // cursor can be set.  This is done again below.
     // winminheight and winminwidth need to be set to avoid an error if the
     // user has set winheight or winwidth.
-    if (put_line(fd, "set winminheight=1 winminwidth=1 winheight=1 winwidth=1")
-        == FAIL) {
+    if (put_line(fd, "set winminheight=0") == FAIL
+        || put_line(fd, "set winheight=1") == FAIL
+        || put_line(fd, "set winminwidth=0") == FAIL
+        || put_line(fd, "set winwidth=1") == FAIL) {
       return FAIL;
     }
     if (nr > 1 && ses_winsizes(fd, restore_size, tab_firstwin) == FAIL) {
diff --git a/src/nvim/testdir/test_unlet.vim b/src/nvim/testdir/test_unlet.vim
index dbddffb492..b02bdaab3b 100644
--- a/src/nvim/testdir/test_unlet.vim
+++ b/src/nvim/testdir/test_unlet.vim
@@ -52,3 +52,13 @@ func Test_unlet_env()
 
   unlet $MUST_NOT_BE_AN_ERROR
 endfunc
+
+func Test_unlet_complete()
+  let g:FOOBAR = 1
+  call feedkeys(":unlet g:FOO\t\n", 'tx')
+  call assert_true(!exists('g:FOOBAR'))
+
+  let $FOOBAR = 1
+  call feedkeys(":unlet $FOO\t\n", 'tx')
+  call assert_true(!exists('$FOOBAR') || empty($FOOBAR))
+endfunc