startup: Avoid VimL global. Introduce TriState enum.

- `syntax_on` is documented. Rather than introduce a new undocumented
  VimL global `g:syntax_off`, use a module-local flag.
- Rename "maybe" functions to follow style guidelines (use standard
  module prefix)

1 files changed, 14 insertions, 7 deletions

diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index ce19320331..b7d8a19de9 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -41,6 +41,8 @@
 #include "nvim/os/os.h"
 #include "nvim/os/time.h"
 
+static bool did_syntax_onoff = false;
+
 // Structure that stores information about a highlight group.
 // The ID of a highlight group is also called group ID.  It is the index in
 // the highlight_ga array PLUS ONE.
@@ -3288,19 +3290,24 @@ static void syn_cmd_off(exarg_T *eap, int syncing)
 static void syn_cmd_onoff(exarg_T *eap, char *name)
   FUNC_ATTR_NONNULL_ALL
 {
+  did_syntax_onoff = true;
   eap->nextcmd = check_nextcmd(eap->arg);
   if (!eap->skip) {
-    syn_cmd(name);
+    char buf[100];
+    strncpy(buf, "so ", 3);
+    vim_snprintf(buf + 3, sizeof(buf) - 3, SYNTAX_FNAME, name);
+    do_cmdline_cmd(buf);
   }
 }
 
-void syn_cmd(char *name)
-  FUNC_ATTR_NONNULL_ALL
+void syn_maybe_on(void)
 {
-  char buf[100];
-  strncpy(buf, "so ", 3);
-  vim_snprintf(buf + 3, sizeof(buf) - 3, SYNTAX_FNAME, name);
-  do_cmdline_cmd(buf);
+  if (!did_syntax_onoff) {
+    exarg_T ea;
+    ea.arg = (char_u *)"";
+    ea.skip = false;
+    syn_cmd_onoff(&ea, "syntax");
+  }
 }
 
 /*