patch 9.0.2074: Completion menu may be wrongv9.0.2074

Problem:  Completion menu may be wrong
Solution: Check for the original direction of the completion menu,
          add more tests, make it work with 'noselect'

completion: move in right direction when  filling completion_info()

When moving through the insert completion menu and switching directions,
we need to make sure we start at the correct position in the list and
move correctly forward/backwards through it, so that we do not skip
entries and the selected item points to the correct entry in the list
of completion entries generated by the completion_info() function.

The general case is this:

1) CTRL-X CTRL-N, we will traverse the list starting from
   compl_first_match and then go forwards (using the cp->next pointer)
   through the list (skipping the very first entry, which has the
   CP_ORIGINAL_TEXT flag set (since that is the empty/non-selected entry

2) CTRL-X CTRL-P, we will traverse the list starting from
   compl_first_match (which now points to the last entry). The previous
   entry will have the CP_ORIGINAL_TEXT flag set, so we need to start
   traversing the list from the second prev pointer.

There are in fact 2 special cases after starting the completion menu
with CTRL-X:

3)  CTRL-N and then going backwards by pressing CTRL-P again.
    compl_first_match will point to the same entry as in step 1 above,
    but since compl_dir_foward() has been switched by pressing CTRL-P
    to backwards we need to pretend to be in still in case 1 and still
    traverse the list in forward direction using the cp_next pointer

4)  CTRL-P and then going forwards by pressing CTRL-N again.
    compl_first_match will point to the same entry as in step 2 above,
    but since compl_dir_foward() has been switched by pressing CTRL-N
    to forwards we need to pretend to be in still in case 2 and still
    traverse the list in backward direction using the cp_prev pointer

For the 'noselect' case however, this is slightly different again. When
going backwards, we only need to go one cp_prev pointer back. And
resting of the direction works again slightly different. So we need to
take the noselect option into account when deciding in which direction
to iterate through the list of matches.

related: #13402
related: #12971
closes: #13408

Signed-off-by: Christian Brabandt <cb@256bit.org>

3 files changed, 102 insertions, 5 deletions

diff --git a/src/insexpand.c b/src/insexpand.c
index ad4edc184e..43fb8ca505 100644
--- a/src/insexpand.c
+++ b/src/insexpand.c
@@ -3044,14 +3044,44 @@ ins_compl_update_sequence_numbers(void)
 info_add_completion_info(list_T *li)
 {
     compl_T	*match;
+    int		forward = compl_dir_forward();
 
     if (compl_first_match == NULL)
 	return OK;
 
+    match = compl_first_match;
+    // There are four cases to consider here:
+    // 1) when just going forward through the menu,
+    //    compl_first_match should point to the initial entry with
+    //    number zero and CP_ORIGINAL_TEXT flag set
+    // 2) when just going backwards,
+    //    compl-first_match should point to the last entry before
+    //    the entry with the CP_ORIGINAL_TEXT flag set
+    // 3) when first going forwards and then backwards, e.g.
+    //    pressing C-N, C-P, compl_first_match points to the
+    //    last entry before the entry with the CP_ORIGINAL_TEXT
+    //    flag set and next-entry moves opposite through the list
+    //    compared to case 2, so pretend the direction is forward again
+    // 4) when first going backwards and then forwards, e.g.
+    //    pressing C-P, C-N, compl_first_match points to the
+    //    first entry with the CP_ORIGINAL_TEXT
+    //    flag set and next-entry moves in opposite direction through the list
+    //    compared to case 1, so pretend the direction is backwards again
+    //
+    // But only do this when the 'noselect' option is not active!
+
+    if (!compl_no_select)
+    {
+	if (forward && !match_at_original_text(match))
+	    forward = FALSE;
+	else if (!forward && match_at_original_text(match))
+	    forward = TRUE;
+    }
+
     // Skip the element with the CP_ORIGINAL_TEXT flag at the beginning, in case of
     // forward completion, or at the end, in case of backward completion.
-    match = compl_dir_forward()
-	    ? compl_first_match->cp_next : compl_first_match->cp_prev->cp_prev;
+    match = forward ? match->cp_next : (compl_no_select ? match->cp_prev : match->cp_prev->cp_prev);
+
     while (match != NULL && !match_at_original_text(match))
     {
 	dict_T *di = dict_alloc();
@@ -3071,7 +3101,7 @@ info_add_completion_info(list_T *li)
 	else
 	    dict_add_tv(di, "user_data", &match->cp_user_data);
 
-	match = compl_dir_forward() ? match->cp_next : match->cp_prev;
+	match = forward ? match->cp_next : match->cp_prev;
     }
 
     return OK;
diff --git a/src/testdir/test_ins_complete.vim b/src/testdir/test_ins_complete.vim
index a4ac26e06c..3e6d8da7da 100644
--- a/src/testdir/test_ins_complete.vim
+++ b/src/testdir/test_ins_complete.vim
@@ -2267,17 +2267,72 @@ func Test_complete_info_index()
   " Ensure 'index' in complete_info() is coherent with the 'items' array.
 
   set completeopt=menu,preview
-  " Search forward.
+  " Search forward
   call feedkeys("Go\<C-X>\<C-N>\<F5>\<Esc>_dd", 'tx')
   call assert_equal("aaa", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
   call feedkeys("Go\<C-X>\<C-N>\<C-N>\<F5>\<Esc>_dd", 'tx')
   call assert_equal("bbb", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  call feedkeys("Go\<C-X>\<C-N>\<C-N>\<C-N>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("ccc", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  call feedkeys("Go\<C-X>\<C-N>\<C-N>\<C-N>\<C-N>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("ddd", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  call feedkeys("Go\<C-X>\<C-N>\<C-N>\<C-N>\<C-N>\<C-N>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("eee", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  call feedkeys("Go\<C-X>\<C-N>\<C-N>\<C-N>\<C-N>\<C-N>\<C-N>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("fff", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  " Search forward: unselected item
+  call feedkeys("Go\<C-X>\<C-N>\<C-N>\<C-N>\<C-N>\<C-N>\<C-N>\<C-N>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal(6 , len(g:compl_info['items']))
+  call assert_equal(-1 , g:compl_info['selected'])
 
-  " Search backward.
+  " Search backward
   call feedkeys("Go\<C-X>\<C-P>\<F5>\<Esc>_dd", 'tx')
   call assert_equal("fff", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
   call feedkeys("Go\<C-X>\<C-P>\<C-P>\<F5>\<Esc>_dd", 'tx')
   call assert_equal("eee", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  call feedkeys("Go\<C-X>\<C-P>\<C-P>\<C-P>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("ddd", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  call feedkeys("Go\<C-X>\<C-P>\<C-P>\<C-P>\<C-P>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("ccc", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  call feedkeys("Go\<C-X>\<C-P>\<C-P>\<C-P>\<C-P>\<C-P>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("bbb", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  call feedkeys("Go\<C-X>\<C-P>\<C-P>\<C-P>\<C-P>\<C-P>\<C-P>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("aaa", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  " search backwards: unselected item
+  call feedkeys("Go\<C-X>\<C-P>\<C-P>\<C-P>\<C-P>\<C-P>\<C-P>\<C-P>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal(6 , len(g:compl_info['items']))
+  call assert_equal(-1 , g:compl_info['selected'])
+
+  " switch direction: forwards, then backwards
+  call feedkeys("Go\<C-X>\<C-N>\<C-P>\<C-P>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("fff", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  " switch direction: forwards, then backwards, then forwards again
+  call feedkeys("Go\<C-X>\<C-N>\<C-P>\<C-P>\<F5>\<Esc>_dd", 'tx')
+  call feedkeys("Go\<C-X>\<C-N>\<C-N>\<C-P>\<C-P>\<C-N>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("aaa", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+
+  " switch direction: backwards, then forwards
+  call feedkeys("Go\<C-X>\<C-P>\<C-N>\<C-N>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("aaa", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  " switch direction: backwards, then forwards, then backwards again
+  call feedkeys("Go\<C-X>\<C-P>\<C-P>\<C-N>\<C-N>\<C-P>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("fff", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call assert_equal(6 , len(g:compl_info['items']))
 
   " Add 'noselect', check that 'selected' is -1 when nothing is selected.
   set completeopt+=noselect
@@ -2289,6 +2344,16 @@ func Test_complete_info_index()
   call feedkeys("Go\<C-X>\<C-P>\<F5>\<Esc>_dd", 'tx')
   call assert_equal(-1, g:compl_info['selected'])
 
+  " Check if index out of range
+  " https://github.com/vim/vim/pull/12971
+  call feedkeys("Go\<C-X>\<C-N>\<C-P>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal(0, g:compl_info['selected'])
+  call assert_equal(6 , len(g:compl_info['items']))
+  call assert_equal("fff", g:compl_info['items'][g:compl_info['selected']]['word'])
+  call feedkeys("Go\<C-X>\<C-N>\<C-N>\<C-N>\<C-N>\<C-N>\<C-N>\<C-N>\<C-N>\<C-N>\<F5>\<Esc>_dd", 'tx')
+  call assert_equal("aaa", g:compl_info['items'][g:compl_info['selected']]['word']) 
+  call assert_equal(6 , len(g:compl_info['items']))
+
   set completeopt&
   bwipe!
 endfunc
diff --git a/src/version.c b/src/version.c
index ec86352ed6..55465a2147 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2074,
+/**/
     2073,
 /**/
     2072,