From a1049546a2577b8458e64d526dbb3ad866448e6a Mon Sep 17 00:00:00 2001
From: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>
Date: Thu, 11 Jan 2024 22:58:36 +0100
Subject: [PATCH] gpui: Validate font contents at load time.

During layout of EditorElement we use 'm' character from current font to calculate sizes, panicking with fonts that do not have that character (e.g. Arabic fonts). It's not really EditorElement's fault, as it assumes that the font it's dealing with is gonna have that character available.
To prevent a crash, I added validation while loading a family that a given font contains the glyphs we're gonna use down the line.
---
 crates/gpui/src/platform/mac/text_system.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/crates/gpui/src/platform/mac/text_system.rs b/crates/gpui/src/platform/mac/text_system.rs
index 79ffb8dc8e..68f4a63326 100644
--- a/crates/gpui/src/platform/mac/text_system.rs
+++ b/crates/gpui/src/platform/mac/text_system.rs
@@ -190,6 +190,9 @@ impl MacTextSystemState {
         for font in family.fonts() {
             let mut font = font.load()?;
             open_type::apply_features(&mut font, features);
+            let Some(_) = font.glyph_for_char('m') else {
+                continue;
+            };
             let font_id = FontId(self.fonts.len());
             font_ids.push(font_id);
             let postscript_name = font.postscript_name().unwrap();