vim-patch:8.2.3743: ":sign" can add a highlight group without a name

Problem:    ":sign" can add a highlight group without a name.
Solution:   Give an error if the group name is missing. (closes vim/vim#9280)
https://github.com/vim/vim/commit/5e18ccc60bdddc4aa39ab039f1a7c918f29e67ce

3 files changed, 31 insertions, 0 deletions

diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index b2422fd531..46506a59cb 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -997,6 +997,8 @@ EXTERN char e_non_empty_string_required[] INIT(= N_("E1142: Non-empty string req
 
 EXTERN char e_cannot_define_autocommands_for_all_events[] INIT(= N_("E1155: Cannot define autocommands for ALL events"));
 
+EXTERN char e_group_name_missing_for_str[] INIT(= N_("E1249: Group name missing for %s"));
+
 EXTERN char top_bot_msg[] INIT(= N_("search hit TOP, continuing at BOTTOM"));
 EXTERN char bot_top_msg[] INIT(= N_("search hit BOTTOM, continuing at TOP"));
 
diff --git a/src/nvim/sign.c b/src/nvim/sign.c
index d2faac2b94..ec0e50f6d4 100644
--- a/src/nvim/sign.c
+++ b/src/nvim/sign.c
@@ -1132,6 +1132,15 @@ linenr_T sign_jump(int sign_id, char_u *sign_group, buf_T *buf)
   return lnum;
 }
 
+static int check_empty_group(size_t len, char *name)
+{
+  if (len == 0) {
+    semsg(_(e_group_name_missing_for_str), name);
+    return FAIL;
+  }
+  return OK;
+}
+
 /// ":sign define {name} ..." command
 static void sign_define_cmd(char_u *sign_name, char_u *cmdline)
 {
@@ -1160,15 +1169,31 @@ static void sign_define_cmd(char_u *sign_name, char_u *cmdline)
       text = vim_strnsave(arg, (size_t)(p - arg));
     } else if (STRNCMP(arg, "linehl=", 7) == 0) {
       arg += 7;
+      if (check_empty_group(p - arg, "linehl") == FAIL) {
+        failed = true;
+        break;
+      }
       linehl = vim_strnsave(arg, (size_t)(p - arg));
     } else if (STRNCMP(arg, "texthl=", 7) == 0) {
       arg += 7;
+      if (check_empty_group(p - arg, "texthl") == FAIL) {
+        failed = true;
+        break;
+      }
       texthl = vim_strnsave(arg, (size_t)(p - arg));
     } else if (STRNCMP(arg, "culhl=", 6) == 0) {
       arg += 6;
+      if (check_empty_group(p - arg, "culhl") == FAIL) {
+        failed = true;
+        break;
+      }
       culhl = vim_strnsave(arg, (size_t)(p - arg));
     } else if (STRNCMP(arg, "numhl=", 6) == 0) {
       arg += 6;
+      if (check_empty_group(p - arg, "numhl") == FAIL) {
+        failed = true;
+        break;
+      }
       numhl = vim_strnsave(arg, (size_t)(p - arg));
     } else {
       semsg(_(e_invarg2), arg);
diff --git a/src/nvim/testdir/test_signs.vim b/src/nvim/testdir/test_signs.vim
index 35c80b375a..3afabfa959 100644
--- a/src/nvim/testdir/test_signs.vim
+++ b/src/nvim/testdir/test_signs.vim
@@ -126,6 +126,10 @@ func Test_sign()
   " call assert_fails("sign define Sign4 text= linehl=Comment", 'E239:')
   call assert_fails("sign define Sign4 text=\\ ab  linehl=Comment", 'E239:')
 
+  call assert_fails("sign define Sign4 linehl=", 'E1249: Group name missing for linehl')
+  call assert_fails("sign define Sign4 culhl=", 'E1249: Group name missing for culhl')
+  call assert_fails("sign define Sign4 texthl=", 'E1249: Group name missing for texthl')
+
   " define sign with whitespace
   sign define Sign4 text=\ X linehl=Comment
   sign undefine Sign4