vim-patch:9.1.1166: command-line auto-completion hard with wildmenu

Problem:  command-line auto-completion hard with wildmenu
Solution: implement "noselect" wildoption value (Girish Palya)

When `noselect` is present in `wildmode` and 'wildmenu' is enabled, the
completion menu appears without pre-selecting the first item.

This change makes it easier to implement command-line auto-completion,
where the menu dynamically appears as characters are typed, and `<Tab>`
can be used to manually select an item. This can be achieved by
leveraging the `CmdlineChanged` event to insert `wildchar(m)`,
triggering completion menu.

Without this change, auto-completion using the 'wildmenu' mechanism is
not feasible, as it automatically inserts the first match, preventing
dynamic selection.

The following Vimscript snippet demonstrates how to configure
auto-completion using `noselect`:

```vim
vim9script
set wim=noselect:lastused,full wop=pum wcm=<C-@> wmnu
autocmd CmdlineChanged : timer_start(0, function(CmdComplete, [getcmdline()]))

def CmdComplete(cur_cmdline: string, timer: number)
  var [cmdline, curpos] = [getcmdline(), getcmdpos()]
  if cur_cmdline ==# cmdline  # Avoid completing each character in keymaps and pasted text
    && !pumvisible() && curpos == cmdline->len() + 1

    if cmdline[curpos - 2] =~ '[\w*/:]'  # Reduce noise by completing only selected characters
      feedkeys("\<C-@>", "ti")
      set eventignore+=CmdlineChanged  # Suppress redundant completion attempts
      timer_start(0, (_) => {
        getcmdline()->substitute('\%x00$', '', '')->setcmdline()  # Remove <C-@> if no completion items exist
        set eventignore-=CmdlineChanged
      })
    endif
  endif
enddef
```

fixes: vim/vim#16551
closes: vim/vim#16759

https://github.com/vim/vim/commit/2bacc3e5fb3569e0fd98e129cb1e422ca18b80a6

Cherry-pick Wildmode_Tests() change from patch 9.0.0418.

Co-authored-by: Girish Palya <girishji@gmail.com>
Signed-off-by: Tomas Slusny <slusnucky@gmail.com>

2 files changed, 56 insertions, 6 deletions

diff --git a/test/old/testdir/gen_opt_test.vim b/test/old/testdir/gen_opt_test.vim
index 64876ce318..d1d27cf578 100644
--- a/test/old/testdir/gen_opt_test.vim
+++ b/test/old/testdir/gen_opt_test.vim
@@ -352,6 +352,7 @@ let test_values = {
       \		'bs'],
       \		['xxx']],
       \ 'wildmode': [['', 'full', 'longest', 'list', 'lastused', 'list:full',
+      \		'noselect', 'noselect,full', 'noselect:lastused,full',
       \		'full,longest', 'full,full,full,full'],
       \		['xxx', 'a4', 'full,full,full,full,full']],
       \ 'wildoptions': [['', 'tagfile', 'pum', 'fuzzy'], ['xxx']],
diff --git a/test/old/testdir/test_cmdline.vim b/test/old/testdir/test_cmdline.vim
index d4ad63d43e..d9496ba2a6 100644
--- a/test/old/testdir/test_cmdline.vim
+++ b/test/old/testdir/test_cmdline.vim
@@ -2168,22 +2168,58 @@ func Wildmode_tests()
   call assert_equal('AAA    AAAA   AAAAA', g:Sline)
   call assert_equal('"b A', @:)
 
+  " When 'wildmenu' is not set, 'noselect' completes first item
+  set wildmode=noselect
+  call feedkeys(":MyCmd o\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd oneA', @:)
+
+  " When 'noselect' is present, do not complete first <tab>.
+  set wildmenu
+  set wildmode=noselect
+  call feedkeys(":MyCmd o\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd o', @:)
+  call feedkeys(":MyCmd o\t\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd o', @:)
+  call feedkeys(":MyCmd o\t\t\<C-Y>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd o', @:)
+
+  " When 'full' is present, complete after first <tab>.
+  set wildmode=noselect,full
+  call feedkeys(":MyCmd o\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd o', @:)
+  call feedkeys(":MyCmd o\t\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd oneA', @:)
+  call feedkeys(":MyCmd o\t\t\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd oneB', @:)
+  call feedkeys(":MyCmd o\t\t\t\<C-Y>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd oneB', @:)
+
+  " 'noselect' has no effect when 'longest' is present.
+  set wildmode=noselect:longest
+  call feedkeys(":MyCmd o\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd one', @:)
+
+  " Complete 'noselect' value in 'wildmode' option
+  set wildmode&
+  call feedkeys(":set wildmode=n\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"set wildmode=noselect', @:)
+  call feedkeys(":set wildmode=\t\t\t\t\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"set wildmode=noselect', @:)
+
   " when using longest completion match, matches shorter than the argument
   " should be ignored (happens with :help)
   set wildmode=longest,full
-  set wildmenu
   call feedkeys(":help a*\t\<C-B>\"\<CR>", 'xt')
   call assert_equal('"help a', @:)
   " non existing file
   call feedkeys(":e a1b2y3z4\t\<C-B>\"\<CR>", 'xt')
   call assert_equal('"e a1b2y3z4', @:)
-  set wildmenu&
 
   " Test for longest file name completion with 'fileignorecase'
   " On MS-Windows, file names are case insensitive.
   if has('unix')
-    call writefile([], 'XTESTfoo')
-    call writefile([], 'Xtestbar')
+    call writefile([], 'XTESTfoo', 'D')
+    call writefile([], 'Xtestbar', 'D')
     set nofileignorecase
     call feedkeys(":e XT\<Tab>\<C-B>\"\<CR>", 'xt')
     call assert_equal('"e XTESTfoo', @:)
@@ -2195,10 +2231,23 @@ func Wildmode_tests()
     call feedkeys(":e Xt\<Tab>\<C-B>\"\<CR>", 'xt')
     call assert_equal('"e Xtest', @:)
     set fileignorecase&
-    call delete('XTESTfoo')
-    call delete('Xtestbar')
   endif
 
+  " If 'noselect' is present, single item menu should not insert item
+  func! T(a, c, p)
+    return "oneA"
+  endfunc
+  command! -nargs=1 -complete=custom,T MyCmd
+  set wildmode=noselect,full
+  call feedkeys(":MyCmd o\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd o', @:)
+  call feedkeys(":MyCmd o\t\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd oneA', @:)
+  " 'nowildmenu' should make 'noselect' ineffective
+  set nowildmenu
+  call feedkeys(":MyCmd o\t\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"MyCmd oneA', @:)
+
   %argdelete
   delcommand MyCmd
   delfunc T