From 99074c6dc3a6492c00603748e36ce0f7321a0de4 Mon Sep 17 00:00:00 2001
From: Wez Furlong <wez@wezfurlong.org>
Date: Wed, 11 Aug 2021 22:37:07 -0700
Subject: [PATCH] font: avoid running out of fallbacks!

The recent presentation logic needs to be tweaked to ensure that
we ignore presentation when we reach the fallback font, otherwise
we'll end up in a bad error stack and crash the program.
---
 wezterm-font/src/shaper/harfbuzz.rs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/wezterm-font/src/shaper/harfbuzz.rs b/wezterm-font/src/shaper/harfbuzz.rs
index 7437d9559..836a18190 100644
--- a/wezterm-font/src/shaper/harfbuzz.rs
+++ b/wezterm-font/src/shaper/harfbuzz.rs
@@ -190,10 +190,13 @@ impl HarfbuzzShaper {
         loop {
             match self.load_fallback(font_idx).context("load_fallback")? {
                 Some(mut pair) => {
-                    if let Some(p) = presentation {
-                        if pair.presentation != p {
-                            font_idx += 1;
-                            continue;
+                    // Ignore presentation if we've reached the last resort font
+                    if font_idx + 1 < self.fonts.len() {
+                        if let Some(p) = presentation {
+                            if pair.presentation != p {
+                                font_idx += 1;
+                                continue;
+                            }
                         }
                     }
                     let size = pair.face.set_font_size(font_size, dpi)?;