From 66ec0fc0e16e304497e92cc59996369d981bc9c2 Mon Sep 17 00:00:00 2001
From: Lukas Wirth <lukas@zed.dev>
Date: Thu, 23 Oct 2025 21:22:28 +0200
Subject: [PATCH] Revert zero-width non-joiner insertion in text shaping
 (#41043)

Reverts parts of https://github.com/zed-industries/zed/pull/39928
Closes https://github.com/zed-industries/zed/issues/40987

Release Notes:

- Fixed some fonts rendering with absurd spacing on MacOS
---
 crates/gpui/src/platform/mac/text_system.rs | 29 ---------------------
 1 file changed, 29 deletions(-)

diff --git a/crates/gpui/src/platform/mac/text_system.rs b/crates/gpui/src/platform/mac/text_system.rs
index 3d89ba79f316ca526af03eb274290d7d30aa190c..a0f90587d862d885e85b2052ce4f55f3cd5da55d 100644
--- a/crates/gpui/src/platform/mac/text_system.rs
+++ b/crates/gpui/src/platform/mac/text_system.rs
@@ -67,8 +67,6 @@ struct MacTextSystemState {
     font_ids_by_postscript_name: HashMap<String, FontId>,
     font_ids_by_font_key: HashMap<FontKey, SmallVec<[FontId; 4]>>,
     postscript_names_by_font_id: HashMap<FontId, String>,
-    /// UTF-16 indices of ZWNJS
-    zwnjs_scratch_space: Vec<usize>,
 }
 
 impl MacTextSystem {
@@ -81,7 +79,6 @@ impl MacTextSystem {
             font_ids_by_postscript_name: HashMap::default(),
             font_ids_by_font_key: HashMap::default(),
             postscript_names_by_font_id: HashMap::default(),
-            zwnjs_scratch_space: Vec::new(),
         }))
     }
 }
@@ -431,11 +428,6 @@ impl MacTextSystemState {
     }
 
     fn layout_line(&mut self, text: &str, font_size: Pixels, font_runs: &[FontRun]) -> LineLayout {
-        const ZWNJ: char = '\u{200C}';
-        const ZWNJ_STR: &str = "\u{200C}";
-        const ZWNJ_SIZE_16: usize = ZWNJ.len_utf16();
-
-        self.zwnjs_scratch_space.clear();
         // Construct the attributed string, converting UTF8 ranges to UTF16 ranges.
         let mut string = CFMutableAttributedString::new();
         let mut max_ascent = 0.0f32;
@@ -443,26 +435,14 @@ impl MacTextSystemState {
 
         {
             let mut ix_converter = StringIndexConverter::new(&text);
-            let mut last_font_run = None;
             for run in font_runs {
                 let text = &text[ix_converter.utf8_ix..][..run.len];
-                // if the fonts are the same, we need to disconnect the text with a ZWNJ
-                // to prevent core text from forming ligatures between them
-                let needs_zwnj = last_font_run.replace(run.font_id) == Some(run.font_id);
 
                 let utf16_start = string.char_len(); // insert at end of string
                 ix_converter.advance_to_utf8_ix(ix_converter.utf8_ix + run.len);
 
                 // note: replace_str may silently ignore codepoints it dislikes (e.g., BOM at start of string)
                 string.replace_str(&CFString::new(text), CFRange::init(utf16_start, 0));
-                if needs_zwnj {
-                    let zwnjs_pos = string.char_len();
-                    self.zwnjs_scratch_space.push(zwnjs_pos as usize);
-                    string.replace_str(
-                        &CFString::from_static_string(ZWNJ_STR),
-                        CFRange::init(zwnjs_pos, 0),
-                    );
-                }
                 let utf16_end = string.char_len();
 
                 let cf_range = CFRange::init(utf16_start, utf16_end - utf16_start);
@@ -514,15 +494,6 @@ impl MacTextSystemState {
                 .zip(run.string_indices().iter())
             {
                 let mut glyph_utf16_ix = usize::try_from(glyph_utf16_ix).unwrap();
-                let r = self
-                    .zwnjs_scratch_space
-                    .binary_search_by(|&it| it.cmp(&glyph_utf16_ix));
-                match r {
-                    // this glyph is a ZWNJ, skip it
-                    Ok(_) => continue,
-                    // adjust the index to account for the ZWNJs we've inserted
-                    Err(idx) => glyph_utf16_ix -= idx * ZWNJ_SIZE_16,
-                }
                 if ix_converter.utf16_ix > glyph_utf16_ix {
                     // We cannot reuse current index converter, as it can only seek forward. Restart the search.
                     ix_converter = StringIndexConverter::new(text);