main: Stop highlighting empty commands as errors

Fixes zsh-users#501

Author: phy1729

highlighters/main/main-highlighter.zsh

@@ -641,7 +641,6 @@ _zsh_highlight_main_highlighter_highlight_list()
           # Not an option flag; nothing to do.  (If the command line is
           # syntactically valid, ${this_word//:sudo_opt:/} should be
           # non-empty now.)
-          this_word=${this_word//:sudo_opt:/}
         fi
       elif [[ $this_word == *':sudo_arg:'* ]]; then
         next_word+=':sudo_opt:'
@@ -651,15 +650,12 @@ _zsh_highlight_main_highlighter_highlight_list()
 
    # The Great Fork: is this a command word?  Is this a non-command word?
    if [[ -n ${(M)ZSH_HIGHLIGHT_TOKENS_COMMANDSEPARATOR:#"$arg"} ]]; then
-     if _zsh_highlight_main__stack_pop T || _zsh_highlight_main__stack_pop Q; then
+     if _zsh_highlight_main__stack_pop T || _zsh_highlight_main__stack_pop Q ||
+        [[ $this_word == *:sudo_arg:* || $this_word == *:sudo_opt:* ]]; then
        # Missing closing square bracket(s)
        style=unknown-token
-     elif [[ $this_word == *':regular:'* ]]; then
-       # This highlights empty commands (semicolon follows nothing) as an error.
-       # Zsh accepts them, though.
-       style=commandseparator
      else
-       style=unknown-token
+       style=commandseparator
      fi
      if [[ $arg == ';' ]] && $in_array_assignment; then
        # literal newline inside an array assignment

highlighters/main/test-data/always2.zsh

@@ -32,7 +32,7 @@ BUFFER=$'{\nls\n} always { pwd }'
 
 expected_region_highlight=(
   '1 1 reserved-word' # {
-  '2 2 unknown-token' # \n
+  '2 2 commandseparator' # \n
   '3 4 command' # ls
   '5 5 commandseparator' # \n
   '6 6 reserved-word' # }

highlighters/main/test-data/comment-followed.zsh

@@ -33,6 +33,6 @@ BUFFER=$'# foo\ntrue'
 
 expected_region_highlight=(
   '1 5 comment' # # foo
-  '6 6 commandseparator "issue #501"' # \n
+  '6 6 commandseparator' # \n
   '7 10 builtin' # true
 )

highlighters/main/test-data/empty-command.zsh

@@ -32,5 +32,5 @@ BUFFER='echo; ;'
 expected_region_highlight=(
   "1 4 builtin" # echo
   "5 5 commandseparator" # ;
-  "7 7 unknown-token" # ;
+  "7 7 commandseparator" # ;
 )

highlighters/main/test-data/empty-command2.zsh

@@ -35,5 +35,5 @@ BUFFER='echo; ;'
 expected_region_highlight=(
   "1 4 builtin" # echo
   "5 5 commandseparator" # ;
-  "7 7 unknown-token" # ;
+  "7 7 commandseparator" # ;
 )

highlighters/main/test-data/empty-line.zsh

@@ -31,6 +31,6 @@
 BUFFER=$'\\\n; ls'
 
 expected_region_highlight=(
-  '3 3 unknown-token' # ;
+  '3 3 commandseparator' # ;
   '5 6 command' # ls
 )