patch 9.1.0631: wrong completion list displayed with non-existing dir + fuzzy completion

Problem:  wrong completion list displayed with non-existing dir + fuzzy
          completion (kawarimidoll)
Solution: clear list of matches, if leader did not use fuzzy match
          (glepnir)

fixes: #15357
closes: #15365

Signed-off-by: glepnir <glephunter@gmail.com>

src/insexpand.c

@@ -3581,6 +3581,7 @@ get_next_filename_completion(void)
 
 		// Move leader to the file part
 		leader = last_sep + 1;
+		leader_len = STRLEN(leader);
 	    }
 	}
     }
@@ -3643,11 +3644,17 @@ get_next_filename_completion(void)
 	    matches = sorted_matches;
 	    num_matches = fuzzy_indices.ga_len;
 	}
+	else if (leader_len > 0)
+	{
+	    FreeWild(num_matches, matches);
+	    num_matches = 0;
+	}
 
 	vim_free(compl_fuzzy_scores);
 	ga_clear(&fuzzy_indices);
     }
 
+    if (num_matches > 0)
 	ins_compl_add_matches(num_matches, matches, p_fic || p_wic);
 }
 

src/testdir/dumps/Test_pum_highlights_15.dump

@@ -0,0 +1,20 @@
+|/+0&#ffffff0|n|o|n|_|e|x|i|t|_|f|o|l|d|e|r> @58
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|-+2#0000000&@1| |F|i|l|e| |n|a|m|e| |c|o|m|p|l|e|t|i|o|n| |(|^|F|^|N|^|P|)| |P+0#ffffff16#e000002|a|t@1|e|r|n| |n|o|t| |f|o|u|n|d| +0#0000000#ffffff0@24

src/testdir/test_popup.vim

@@ -1493,6 +1493,11 @@ func Test_pum_highlights_match()
   call TermWait(buf, 50)
   call VerifyScreenDump(buf, 'Test_pum_highlights_11', {})
 
+  " issue #15357
+  call term_sendkeys(buf, "\<ESC>S/non_exit_folder\<C-X>\<C-F>")
+  call TermWait(buf, 50)
+  call VerifyScreenDump(buf, 'Test_pum_highlights_15', {})
+
   call term_sendkeys(buf, "\<C-E>\<Esc>")
   call TermWait(buf)
 

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    631,
 /**/
     630,
 /**/