vim-patch:9.1.1374: completion: 'smartcase' not respected when filtering matches

Problem:  Currently, 'smartcase' is respected when completing keywords
          using <C-N>, <C-P>, <C-X><C-N>, and <C-X><C-P>. However, when
          a user continues typing and the completion menu is filtered
          using cached matches, 'smartcase' is not applied. This leads
          to poor-quality or irrelevant completion suggestions, as shown
          in the example below.
Solution: When filtering cached completion items after typing additional
          characters, apply case-sensitive comparison if 'smartcase' is
          enabled and the typed pattern includes uppercase characters.
          This ensures consistent and expected completion behavior.
          (Girish Palya)

closes: vim/vim#17271

dc314053e1

Co-authored-by: Girish Palya <girishji@gmail.com>

runtime/doc/insert.txt

@@ -1297,6 +1297,7 @@ use all space available.
 The 'pumwidth' option can be used to set a minimum width.  The default is 15
 characters.
 
+							*compl-states*
 There are three states:
 1. A complete match has been inserted, e.g., after using CTRL-N or CTRL-P.
 2. A cursor key has been used to select another match.  The match was not

runtime/doc/news.txt

@@ -211,6 +211,7 @@ CHANGED FEATURES                                                 *news-changed*
 
 These existing features changed their behavior.
 
+• 'smartcase' applies to completion filtering.
 • 'spellfile' location defaults to `stdpath("data").."/site/spell/"` instead of
   the first writable directory in 'runtimepath'.
 • |vim.version.range()| doesn't exclude `to` if it is equal to `from`.

runtime/doc/options.txt

@@ -5718,9 +5718,11 @@ A jump table for the options with a short description can be found at |Q_op|.
 	Override the 'ignorecase' option if the search pattern contains upper
 	case characters.  Only used when the search pattern is typed and
 	'ignorecase' option is on.  Used for the commands "/", "?", "n", "N",
-	":g" and ":s".  Not used for "*", "#", "gd", tag search, etc.  After
+	":g" and ":s" and when filtering matches for the completion menu
-	"*" and "#" you can make 'smartcase' used by doing a "/" command,
+	|compl-states|.
-	recalling the search pattern from history and hitting <Enter>.
+	Not used for "*", "#", "gd", tag search, etc.  After "*" and "#" you
+	can make 'smartcase' used by doing a "/" command, recalling the search
+	pattern from history and hitting <Enter>.
 
 			*'smartindent'* *'si'* *'nosmartindent'* *'nosi'*
 'smartindent' 'si'	boolean	(default off)

runtime/lua/vim/_meta/options.lua

@@ -6084,9 +6084,11 @@ vim.wo.scl = vim.wo.signcolumn
 --- Override the 'ignorecase' option if the search pattern contains upper
 --- case characters.  Only used when the search pattern is typed and
 --- 'ignorecase' option is on.  Used for the commands "/", "?", "n", "N",
---- ":g" and ":s".  Not used for "*", "#", "gd", tag search, etc.  After
+--- ":g" and ":s" and when filtering matches for the completion menu
---- "*" and "#" you can make 'smartcase' used by doing a "/" command,
+--- `compl-states`.
---- recalling the search pattern from history and hitting <Enter>.
+--- Not used for "*", "#", "gd", tag search, etc.  After "*" and "#" you
+--- can make 'smartcase' used by doing a "/" command, recalling the search
+--- pattern from history and hitting <Enter>.
 ---
 --- @type boolean
 vim.o.smartcase = false

src/nvim/insexpand.c

@@ -1391,6 +1391,12 @@ static int ins_compl_build_pum(void)
       comp->cp_score = fuzzy_match_str(comp->cp_str.data, compl_leader.data);
     }
 
+    // Apply 'smartcase' behavior during normal mode
+    if (ctrl_x_mode_normal() && !p_inf && compl_leader.data
+        && !ignorecase(compl_leader.data) && !fuzzy_filter) {
+      comp->cp_flags &= ~CP_ICASE;
+    }
+
     if (!match_at_original_text(comp)
         && (compl_leader.data == NULL
             || ins_compl_equal(comp, compl_leader.data, compl_leader.size)

src/nvim/options.lua

@@ -8095,9 +8095,11 @@ local options = {
         Override the 'ignorecase' option if the search pattern contains upper
         case characters.  Only used when the search pattern is typed and
         'ignorecase' option is on.  Used for the commands "/", "?", "n", "N",
-        ":g" and ":s".  Not used for "*", "#", "gd", tag search, etc.  After
+        ":g" and ":s" and when filtering matches for the completion menu
-        "*" and "#" you can make 'smartcase' used by doing a "/" command,
+        |compl-states|.
-        recalling the search pattern from history and hitting <Enter>.
+        Not used for "*", "#", "gd", tag search, etc.  After "*" and "#" you
+        can make 'smartcase' used by doing a "/" command, recalling the search
+        pattern from history and hitting <Enter>.
       ]=],
       full_name = 'smartcase',
       scope = { 'global' },

src/nvim/search.c

@@ -391,7 +391,7 @@ int ignorecase(char *pat)
   return ignorecase_opt(pat, p_ic, p_scs);
 }
 
-/// As ignorecase() put pass the "ic" and "scs" flags.
+/// As ignorecase() but pass the "ic" and "scs" flags.
 int ignorecase_opt(char *pat, int ic_in, int scs)
 {
   int ic = ic_in;

test/old/testdir/test_ins_complete.vim

@@ -3484,6 +3484,93 @@ func Test_complete_append_selected_match_default()
   delfunc PrintMenuWords
 endfunc
 
+" Test normal mode (^N/^P/^X^N/^X^P) with smartcase when 1) matches are first
+" found and 2) matches are filtered (when a character is typed).
+func Test_smartcase_normal_mode()
+
+  func! PrintMenu()
+    let info = complete_info(["matches"])
+    call map(info.matches, {_, v -> v.word})
+    return info
+  endfunc
+
+  func! TestInner(key)
+    let pr = "\<c-r>=PrintMenu()\<cr>"
+
+    new
+    set completeopt=menuone,noselect ignorecase smartcase
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOF{a:key}{pr}"
+    call assert_equal('F{''matches'': [''Fast'', ''FAST'', ''False'',
+          \ ''FALSE'']}', getline(1))
+    %d
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOF{a:key}a{pr}"
+    call assert_equal('Fa{''matches'': [''Fast'', ''False'']}', getline(1))
+    %d
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOF{a:key}a\<bs>{pr}"
+    call assert_equal('F{''matches'': [''Fast'', ''FAST'', ''False'',
+          \ ''FALSE'']}', getline(1))
+    %d
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOF{a:key}ax{pr}"
+    call assert_equal('Fax{''matches'': []}', getline(1))
+    %d
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOF{a:key}ax\<bs>{pr}"
+    call assert_equal('Fa{''matches'': [''Fast'', ''False'']}', getline(1))
+
+    %d
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOF{a:key}A{pr}"
+    call assert_equal('FA{''matches'': [''FAST'', ''FALSE'']}', getline(1))
+    %d
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOF{a:key}A\<bs>{pr}"
+    call assert_equal('F{''matches'': [''Fast'', ''FAST'', ''False'',
+          \ ''FALSE'']}', getline(1))
+    %d
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOF{a:key}AL{pr}"
+    call assert_equal('FAL{''matches'': [''FALSE'']}', getline(1))
+    %d
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOF{a:key}ALx{pr}"
+    call assert_equal('FALx{''matches'': []}', getline(1))
+    %d
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOF{a:key}ALx\<bs>{pr}"
+    call assert_equal('FAL{''matches'': [''FALSE'']}', getline(1))
+
+    %d
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOf{a:key}{pr}"
+    call assert_equal('f{''matches'': [''Fast'', ''FAST'', ''False'', ''FALSE'',
+          \ ''fast'', ''false'']}', getline(1))
+    %d
+    call setline(1, ["Fast", "FAST", "False", "FALSE", "fast", "false"])
+    exe $"normal! ggOf{a:key}a{pr}"
+    call assert_equal('fa{''matches'': [''Fast'', ''FAST'', ''False'', ''FALSE'',
+          \ ''fast'', ''false'']}', getline(1))
+
+    %d
+    exe $"normal! ggOf{a:key}{pr}"
+    call assert_equal('f{''matches'': []}', getline(1))
+    exe $"normal! ggOf{a:key}a\<bs>{pr}"
+    call assert_equal('f{''matches'': []}', getline(1))
+    set ignorecase& smartcase& completeopt&
+    bw!
+  endfunc
+
+  call TestInner("\<c-n>")
+  call TestInner("\<c-p>")
+  call TestInner("\<c-x>\<c-n>")
+  call TestInner("\<c-x>\<c-p>")
+  delfunc PrintMenu
+  delfunc TestInner
+endfunc
+
 " Test 'nearest' flag of 'completeopt'
 func Test_nearest_cpt_option()