feat(mbyte): support extended grapheme clusters including more emoji

Use the grapheme break algorithm from utf8proc to support grapheme
clusters from recent unicode versions.

Handle variant selector VS16 turning some codepoints into double-width
emoji. This means we need to use ptr2cells rather than char2cells when
possible.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/nvim/change.c b/src/nvim/change.c
index 6e9fab5a9b..47a9f0ce92 100644
--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@@ -896,14 +896,15 @@ int del_bytes(colnr_T count, bool fixpos_arg, bool use_delcombine)
   // delete the last combining character.
   if (p_deco && use_delcombine && utfc_ptr2len(oldp + col) >= count) {
     char *p0 = oldp + col;
-    if (utf_composinglike(p0, p0 + utf_ptr2len(p0))) {
+    GraphemeState state = GRAPHEME_STATE_INIT;
+    if (utf_composinglike(p0, p0 + utf_ptr2len(p0), &state)) {
       // Find the last composing char, there can be several.
       int n = col;
       do {
         col = n;
         count = utf_ptr2len(oldp + n);
         n += count;
-      } while (utf_composinglike(oldp + col, oldp + n));
+      } while (utf_composinglike(oldp + col, oldp + n, &state));
       fixpos = false;
     }
   }
@@ -1694,7 +1695,7 @@ bool open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
     }
     if (curbuf->b_p_ai || (flags & OPENLINE_DELSPACES)) {
       while ((*p_extra == ' ' || *p_extra == '\t')
-             && !utf_iscomposing(utf_ptr2char(p_extra + 1))) {
+             && !utf_iscomposing_first(utf_ptr2char(p_extra + 1))) {
         if (REPLACE_NORMAL(State)) {
           replace_push(*p_extra);
         }