Merge #9078 from janlazo/vim-8.0.1832

runtime/doc/eval.txt

@@ -9136,6 +9136,14 @@ This does NOT work: >
 			variables are automatically deleted when the function
 			ends.
 
+:unl[et] ${env-name} ...			*:unlet-environment* *:unlet-$*
+			Remove environment variable {env-name}.
+			Can mix {name} and ${env-name} in one :unlet command.
+			No error message is given for a non-existing
+			variable, also without !.
+			If the system does not support deleting an environment
+			variable, it is made emtpy.
+
 :lockv[ar][!] [depth] {name} ...			*:lockvar* *:lockv*
 			Lock the internal variable {name}.  Locking means that
 			it can no longer be changed (until it is unlocked).

src/nvim/eval.c

@@ -2818,6 +2818,18 @@ static void ex_unletlock(exarg_T *eap, char_u *argstart, int deep)
   lval_T lv;
 
   do {
+    if (*arg == '$') {
+      const char *name = (char *)++arg;
+
+      if (get_env_len((const char_u **)&arg) == 0) {
+        EMSG2(_(e_invarg2), name - 1);
+        return;
+      }
+      os_unsetenv(name);
+      arg = skipwhite(arg);
+      continue;
+    }
+
     // Parse the name and find the end.
     char_u *const name_end = (char_u *)get_lval(arg, NULL, &lv, true,
                                                 eap->skip || error,

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) {

src/nvim/testdir/test_unlet.vim

@@ -28,3 +28,37 @@ endfunc
 func Test_unlet_fails()
   call assert_fails('unlet v:["count"]', 'E46:')
 endfunc
+
+func Test_unlet_env()
+  let envcmd = has('win32') ? 'set' : 'env'
+
+  let $FOOBAR = 'test'
+  let found = 0
+  for kv in split(system(envcmd), "\r*\n")
+    if kv == 'FOOBAR=test'
+      let found = 1
+    endif
+  endfor
+  call assert_equal(1, found)
+
+  unlet $FOOBAR
+  let found = 0
+  for kv in split(system(envcmd), "\r*\n")
+    if kv == 'FOOBAR=test'
+      let found = 1
+    endif
+  endfor
+  call assert_equal(0, found)
+
+  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