patch 9.1.1287: quickfix code can be further improved

Problem:  quickfix code can be further improved (after v9.1.1283)
Solution: slightly refactor quickfix.c (Hirohito Higashi)

- remove error message output
- adjust comments
- rename functions:
  - qf_init_quickfix_stack() --> qf_init_stack()
  - qf_resize_quickfix_stack() --> qf_resize_stack()
  - qf_resize_stack() --> qf_resize_stack_base()

Now qf_alloc_stack() can handle both quickfix/location lists.

closes: #17068

Signed-off-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/quickfix.c b/src/quickfix.c
index 9722058..decc01b 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -174,7 +174,7 @@
 static void     qf_pop_stack(qf_info_T *qi, int adjust);
 static void	qf_new_list(qf_info_T *qi, char_u *qf_title);
 static int	qf_add_entry(qf_list_T *qfl, char_u *dir, char_u *fname, char_u *module, int bufnum, char_u *mesg, long lnum, long end_lnum, int col, int end_col, int vis_col, char_u *pattern, int nr, int type, typval_T *user_data, int valid);
-static int      qf_resize_stack(qf_info_T *qi, int n);
+static int      qf_resize_stack_base(qf_info_T *qi, int n);
 static void     qf_sync_llw_to_win(win_T *llw);
 static void     qf_sync_win_to_llw(win_T *pwp);
 static qf_info_T *qf_alloc_stack(qfltype_T qfltype, int n);
@@ -2343,19 +2343,16 @@
 }
 
 /*
- * Resize global quickfix stack to be able to hold n amount of lists.
+ * Resize quickfix stack to be able to hold n amount of lists.
  * returns FAIL on failure and OK on success.
  */
     int
-qf_resize_quickfix_stack(int n)
+qf_resize_stack(int n)
 {
     if (ql_info == NULL)
-    {
-	emsg(_(e_no_quickfix_stack));
 	return FAIL;
-    }
 
-    if (qf_resize_stack(ql_info, n) == FAIL)
+    if (qf_resize_stack_base(ql_info, n) == FAIL)
 	return FAIL;
 
     return OK;
@@ -2376,22 +2373,28 @@
 	qf_sync_win_to_llw(wp);
 
     qf_info_T *qi = ll_get_or_alloc_list(wp);
+    if (qi == NULL)
+	return FAIL;
 
-    if (qf_resize_stack(qi, n) == FAIL)
+    if (qf_resize_stack_base(qi, n) == FAIL)
 	return FAIL;
 
     return OK;
 }
 
 /*
- * Resize quickfix stack to be able to hold n amount of quickfix lists.
+ * Resize quickfix/location lists stack to be able to hold n amount of lists.
  * Returns FAIL on failure and OK on success.
  */
     static int
-qf_resize_stack(qf_info_T *qi, int n)
+qf_resize_stack_base(qf_info_T *qi, int n)
 {
     qf_list_T *new;
     int amount_to_rm = 0, i;
+
+    if (qi == NULL)
+	return FAIL;
+
     size_t lsz = sizeof(*qi->qf_lists);
 
     if (n == qi->qf_maxcount)
@@ -2424,21 +2427,12 @@
 }
 
 /*
- * Initialize global quickfix list, should only be called once.
- * Returns FAIL on failure and OK on success.
+ * Initialize quickfix list, should only be called once.
  */
-   int
-qf_init_quickfix_stack(void)
+   void
+qf_init_stack(void)
 {
-    ql_info_actual.qf_lists = qf_alloc_list_stack(p_chi);
-
-    if (ql_info_actual.qf_lists == NULL)
-	return FAIL;
-
-    ql_info = &ql_info_actual;
-    ql_info->qfl_type = QFLT_QUICKFIX;
-    ql_info->qf_maxcount = p_chi;
-    return OK;
+    ql_info = qf_alloc_stack(QFLT_QUICKFIX, p_chi);
 }
 
 /*
@@ -2480,22 +2474,24 @@
 {
     qf_info_T *qi;
 
-    qi = ALLOC_CLEAR_ONE_ID(qf_info_T, aid_qf_qfinfo);
-    if (qi == NULL)
-	return NULL;
-
-    qi->qf_refcount++;
+    if (qfltype == QFLT_QUICKFIX)
+	qi = &ql_info_actual;
+    else
+    {
+	qi = ALLOC_CLEAR_ONE_ID(qf_info_T, aid_qf_qfinfo);
+	if (qi == NULL)
+	    return NULL;
+	qi->qf_refcount++;
+    }
     qi->qfl_type = qfltype;
     qi->qf_bufnr = INVALID_QFBUFNR;
-
     qi->qf_lists = qf_alloc_list_stack(n);
-
     if (qi->qf_lists == NULL)
     {
-	vim_free(qi);
+	if (qfltype != QFLT_QUICKFIX)
+	    vim_free(qi);
 	return NULL;
     }
-
     qi->qf_maxcount = n;
 
     return qi;
@@ -8259,20 +8255,15 @@
 	char_u	*title,
 	dict_T	*what)
 {
-    qf_info_T	*qi = ql_info;
+    qf_info_T	*qi;
     int		retval = OK;
 
     if (wp != NULL)
-    {
 	qi = ll_get_or_alloc_list(wp);
-	if (qi == NULL)
-	    return FAIL;
-    }
-    else if (qi == NULL)
-    {
-	emsg(_(e_no_quickfix_stack));
+    else
+	qi = ql_info;
+    if (qi == NULL)
 	return FAIL;
-    }
 
     if (action == 'f')
     {