From e12a9f3caf71cd8d96c7d81314d1888156f37a54 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 1 Jun 2022 12:00:53 +0530
Subject: [PATCH] Iosevka: Fix incorrect rendering when there is a combining
 char that does not group with its neighbors

Fixes #5153
---
 docs/changelog.rst   |  3 +++
 kitty/fonts.c        | 12 +++++++++---
 kitty_tests/fonts.py |  1 +
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index ef9aa9d1f..aaadfd28e 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -53,6 +53,9 @@ Detailed list of changes
 - Themes kitten: Add a tab to show user defined custom color themes separately
   (:pull:`5150`)
 
+- Iosevka: Fix incorrect rendering when there is a combining char that does not
+  group with its neighbors (:iss:`5153`)
+
 
 0.25.1 [2022-05-26]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/kitty/fonts.c b/kitty/fonts.c
index d066688b5..454e353d4 100644
--- a/kitty/fonts.c
+++ b/kitty/fonts.c
@@ -928,8 +928,14 @@ group_iosevka(Font *font, hb_font_t *hbf) {
         const LigatureType current = ligature_types[G(glyph_idx)];
         const LigatureType after = is_last_glyph ? LIGATURE_UNKNOWN : ligature_types[G(glyph_idx + 1)];
         bool end_current_group = false;
-        if (current_group->num_glyphs && is_iosevka_lig_ender(before, current, after)) {
-            end_current_group = true;
+        if (current_group->num_glyphs) {
+            if (is_iosevka_lig_ender(before, current, after)) end_current_group = true;
+            else {
+                if (!current_group->num_cells && !current_group->has_special_glyph) {
+                    if (is_iosevka_lig_starter(before, current, after)) current_group->has_special_glyph = true;
+                    else end_current_group = true;
+                }
+            }
         }
         if (!current_group->num_glyphs++) {
             if (is_iosevka_lig_starter(before, current, after)) current_group->has_special_glyph = true;
@@ -954,7 +960,7 @@ group_iosevka(Font *font, hb_font_t *hbf) {
             }
             current_group->num_cells += num_cells_consumed;
         }
-        if (end_current_group) G(group_idx)++;
+        if (end_current_group && current_group->num_cells) G(group_idx)++;
         G(glyph_idx)++;
     }
 }
diff --git a/kitty_tests/fonts.py b/kitty_tests/fonts.py
index 613de3e24..089ce7df4 100644
--- a/kitty_tests/fonts.py
+++ b/kitty_tests/fonts.py
@@ -110,6 +110,7 @@ class Rendering(BaseTest):
                 self.ae(g('===--<>=='), [(3, 3), (2, 2), (2, 2), (2, 2)])
                 self.ae(g('==!=<>==<><><>'), [(4, 4), (2, 2), (2, 2), (2, 2), (2, 2), (2, 2)])
                 self.ae(g('-' * 18), [(18, 18)])
+            self.ae(g('a>\u2060<b'), [(1, 1), (1, 2), (1, 1), (1, 1)])
         colon_glyph = ss('9:30', font='FiraCode-Medium.otf')[1][2]
         self.assertNotEqual(colon_glyph, ss(':', font='FiraCode-Medium.otf')[0][2])
         self.ae(colon_glyph, 1031)