Replace ga->ga_len == 0 checks with GA_EMPTY(ga)

Used Coccinelle to perform the changes

@@
expression E;
@@

<...
(
// E.ga_len == 0 is isomorphic to !E.ga_len
- E.ga_len == 0
+ GA_EMPTY(&E)
|
- E->ga_len == 0
+ GA_EMPTY(E)
)
...>

src/nvim/eval.c

@@ -18397,7 +18397,7 @@ char_u *get_user_func_name(expand_T *xp, int idx)
     cat_func_name(IObuff, fp);
     if (xp->xp_context != EXPAND_USER_FUNC) {
       STRCAT(IObuff, "(");
-      if (!fp->uf_varargs && fp->uf_args.ga_len == 0)
+      if (!fp->uf_varargs && GA_EMPTY(&fp->uf_args))
         STRCAT(IObuff, ")");
     }
     return IObuff;

src/nvim/ex_cmds2.c

@@ -594,7 +594,7 @@ void ex_breakdel(exarg_T *eap)
     }
 
     /* If all breakpoints were removed clear the array. */
-    if (gap->ga_len == 0)
+    if (GA_EMPTY(gap))
       ga_clear(gap);
   }
 }
@@ -607,7 +607,7 @@ void ex_breaklist(exarg_T *eap)
   struct debuggy *bp;
   int i;
 
-  if (dbg_breakp.ga_len == 0)
+  if (GA_EMPTY(&dbg_breakp))
     MSG(_("No breakpoints defined"));
   else
     for (i = 0; i < dbg_breakp.ga_len; ++i) {
@@ -670,7 +670,7 @@ debuggy_find (
   int prev_got_int;
 
   /* Return quickly when there are no breakpoints. */
-  if (gap->ga_len == 0)
+  if (GA_EMPTY(gap))
     return (linenr_T)0;
 
   /* Replace K_SNR in function name with "<SNR>". */

src/nvim/ex_getln.c

@@ -4187,7 +4187,7 @@ static int ExpandRTDir(char_u *pat, int *num_file, char_u ***file, char *dirname
     }
     free(matches);
   }
-  if (ga.ga_len == 0)
+  if (GA_EMPTY(&ga))
     return FAIL;
 
   /* Sort and remove duplicates which can happen when specifying multiple

src/nvim/fold.c

@@ -1013,7 +1013,7 @@ void cloneFoldGrowArray(garray_T *from, garray_T *to)
 
   ga_init(to, from->ga_itemsize, from->ga_growsize);
 
-  if (from->ga_len == 0)
+  if (GA_EMPTY(from))
     return;
 
   ga_grow(to, from->ga_len);
@@ -1302,7 +1302,7 @@ static void deleteFoldEntry(garray_T *gap, int idx, int recursive)
   fold_T      *nfp;
 
   fp = (fold_T *)gap->ga_data + idx;
-  if (recursive || fp->fd_nested.ga_len == 0) {
+  if (recursive || GA_EMPTY(&fp->fd_nested)) {
     /* recursively delete the contained folds */
     deleteFoldRecurse(&fp->fd_nested);
     --gap->ga_len;

src/nvim/path.c

@@ -893,7 +893,7 @@ expand_in_path (
   ga_init(&path_ga, (int)sizeof(char_u *), 1);
   expand_path_option(curdir, &path_ga);
   free(curdir);
-  if (path_ga.ga_len == 0)
+  if (GA_EMPTY(&path_ga))
     return 0;
 
   paths = ga_concat_strings(&path_ga);

src/nvim/regexp.c

@@ -5021,7 +5021,7 @@ regmatch (
     /*
      * If the regstack is empty or something failed we are done.
      */
-    if (regstack.ga_len == 0 || status == RA_FAIL) {
+    if (GA_EMPTY(&regstack) || status == RA_FAIL) {
       if (scan == NULL) {
         /*
          * We get here only if there's trouble -- normally "case END" is

src/nvim/spell.c

@@ -997,7 +997,7 @@ spell_check (
     return 1;
 
   // Return here when loading language files failed.
-  if (wp->w_s->b_langp.ga_len == 0)
+  if (GA_EMPTY(&wp->w_s->b_langp))
     return 1;
 
   memset(&mi, 0, sizeof(matchinf_T));
@@ -1947,7 +1947,7 @@ spell_valid_case (
 static int no_spell_checking(win_T *wp)
 {
   if (!wp->w_p_spell || *wp->w_s->b_p_spl == NUL
-      || wp->w_s->b_langp.ga_len == 0) {
+      || GA_EMPTY(&wp->w_s->b_langp)) {
     EMSG(_("E756: Spell checking is not enabled"));
     return TRUE;
   }
@@ -4557,16 +4557,16 @@ static afffile_T *spell_read_aff(spellinfo_T *spin, char_u *fname)
   spell_message(spin, IObuff);
 
   // Only do REP lines when not done in another .aff file already.
-  do_rep = spin->si_rep.ga_len == 0;
+  do_rep = GA_EMPTY(&spin->si_rep);
 
   // Only do REPSAL lines when not done in another .aff file already.
-  do_repsal = spin->si_repsal.ga_len == 0;
+  do_repsal = GA_EMPTY(&spin->si_repsal);
 
   // Only do SAL lines when not done in another .aff file already.
-  do_sal = spin->si_sal.ga_len == 0;
+  do_sal = GA_EMPTY(&spin->si_sal);
 
   // Only do MAP lines when not done in another .aff file already.
-  do_mapline = spin->si_map.ga_len == 0;
+  do_mapline = GA_EMPTY(&spin->si_map);
 
   // Allocate and init the afffile_T structure.
   aff = (afffile_T *)getroom(spin, sizeof(afffile_T), TRUE);
@@ -6938,7 +6938,7 @@ static int write_vim_spell(spellinfo_T *spin, char_u *fname)
       gap = &spin->si_repsal;
 
     // Don't write the section if there are no items.
-    if (gap->ga_len == 0)
+    if (GA_EMPTY(gap))
       continue;
 
     // Sort the REP/REPSAL items.
@@ -8691,7 +8691,7 @@ void spell_suggest(int count)
   spell_find_suggest(line + curwin->w_cursor.col, badlen, &sug, limit,
       TRUE, need_cap, TRUE);
 
-  if (sug.su_ga.ga_len == 0)
+  if (GA_EMPTY(&sug.su_ga))
     MSG(_("Sorry, no suggestions"));
   else if (count > 0) {
     if (count > sug.su_ga.ga_len)
@@ -11680,7 +11680,7 @@ add_suggestion (
     // the first "the" to itself.
     return;
 
-  if (gap->ga_len == 0)
+  if (GA_EMPTY(gap))
     i = -1;
   else {
     // Check if the word is already there.  Also check the length that is

src/nvim/syntax.c

@@ -2376,12 +2376,12 @@ static void check_state_ends(void)
 
         pop_current_state();
 
-        if (current_state.ga_len == 0)
+        if (GA_EMPTY(&current_state))
           break;
 
         if (had_extend && keepend_level >= 0) {
           syn_update_ends(FALSE);
-          if (current_state.ga_len == 0)
+          if (GA_EMPTY(&current_state))
             break;
         }
 

src/nvim/undo.c

@@ -2419,7 +2419,7 @@ void ex_undolist(exarg_T *eap)
     }
   }
 
-  if (ga.ga_len == 0)
+  if (GA_EMPTY(&ga))
     MSG(_("Nothing to undo"));
   else {
     sort_strings((char_u **)ga.ga_data, ga.ga_len);