patch 9.1.1918: completion: crash with fuzzy completion

Problem:  completion: crash with fuzzy completion
          (Christian Brabandt)
Solution: When completion candidates are gathered from a different
          window, and when completing `<c-p>`, linked list should be
          sorted only after all items are collected (Girish Palya).

fixes: #18752
closes: #18756

Signed-off-by: Girish Palya <girishji@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/insexpand.c

@@ -5710,11 +5710,14 @@ ins_compl_get_exp(pos_T *ini)
     }
     may_trigger_modechanged();
 
-    if (is_nearest_active() && !ins_compl_has_preinsert())
-	sort_compl_match_list(cp_compare_nearest);
+    if (match_count > 0)
+    {
+	if (is_nearest_active() && !ins_compl_has_preinsert())
+	    sort_compl_match_list(cp_compare_nearest);
 
-    if ((get_cot_flags() & COT_FUZZY) && ins_compl_leader_len() > 0)
-	ins_compl_fuzzy_sort();
+	if ((get_cot_flags() & COT_FUZZY) && ins_compl_leader_len() > 0)
+	    ins_compl_fuzzy_sort();
+    }
 
     return match_count;
 }

src/testdir/test_ins_complete.vim

@@ -3705,6 +3705,22 @@ func Test_complete_fuzzy_collect()
   set completeopt& cfc& cpt&
 endfunc
 
+" Issue #18752
+func Test_complete_fuzzy_collect_multiwin()
+  new
+  set completefuzzycollect=keyword,files,whole_line
+  set completeopt=fuzzy
+
+  vnew
+  call setline(1, ["completeness,", "compatibility", "Composite", "Omnipotent"])
+  wincmd p
+  call feedkeys("Somp\<C-P>\<Esc>0", 'tx!')
+  call assert_equal('Omnipotent', getline('.'))
+
+  bw!
+  set completeopt& cfc&
+endfunc
+
 func Test_cfc_with_longest()
   new
   set completefuzzycollect=keyword,files,whole_line

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1918,
 /**/
     1917,
 /**/