From aeb7ff8391f6ebd5de8997ccb3e46afc46ce855e Mon Sep 17 00:00:00 2001
From: Sventurbo <94544175+Sventurbo@users.noreply.github.com>
Date: Thu, 5 Nov 2026 02:44:46 +0100
Subject: [PATCH] M2: read Arial's MT suffix in any letter case (#5889)

is_arial compared the family and style without regard to case but
stripped the MT suffix case-sensitively, so arialmt and Arial-Boldmt
weren't read in Arial's glyph order (CodeRabbit review on #6210). The
suffix is now stripped in any case, slicing only at a char boundary.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../src/raster/tests/non_embedded_arial.rs     | 18 ++++++++++++++----
 vendor/hayro-interpret/src/font/cid.rs         | 18 +++++++++++++-----
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/crates/render/src/raster/tests/non_embedded_arial.rs b/crates/render/src/raster/tests/non_embedded_arial.rs
index b64ea5d0f4..c434bbb7ab 100644
--- a/crates/render/src/raster/tests/non_embedded_arial.rs
+++ b/crates/render/src/raster/tests/non_embedded_arial.rs
@@ -84,10 +84,20 @@ fn without_and_with_unicode(font: Font<'_>) -> (Vec<u8>, Vec<u8>) {
 
 #[test]
 fn an_arial_the_pdf_does_not_embed_draws_the_glyphs_its_codes_name() {
-    // Each face as Windows exporters name it, and as Word names a face it doesn't embed.
-    for base_font in
-        ["ArialMT", "Arial-BoldMT", "Arial-ItalicMT", "Arial-BoldItalicMT", "Arial", "Arial,Bold", "Arial,BoldItalic", "ABCDEF+Arial-BoldMT"]
-    {
+    // Each face as Windows exporters name it, and as Word names a face it doesn't embed. The name
+    // is read without regard to case, `MT` included.
+    for base_font in [
+        "ArialMT",
+        "Arial-BoldMT",
+        "Arial-ItalicMT",
+        "Arial-BoldItalicMT",
+        "Arial",
+        "Arial,Bold",
+        "Arial,BoldItalic",
+        "ABCDEF+Arial-BoldMT",
+        "arialmt",
+        "Arial-Boldmt",
+    ] {
         for mapped in [false, true] {
             let (without, with) = without_and_with_unicode(Font { base_font, subtype: "CIDFontType2", mapped, to_unicode: false });
             assert!(without == with, "{base_font} (CIDToGIDMap {}): the codes draw \"Low É\"", if mapped { "stream" } else { "/Identity" });
diff --git a/vendor/hayro-interpret/src/font/cid.rs b/vendor/hayro-interpret/src/font/cid.rs
index 291e9dde2d..0ed6c20973 100644
--- a/vendor/hayro-interpret/src/font/cid.rs
+++ b/vendor/hayro-interpret/src/font/cid.rs
@@ -634,19 +634,27 @@ fn is_variation_selector(c: char) -> bool {
 /// Arial faces as exporters name them: `ArialMT`, `Arial-BoldMT`, `Arial-ItalicMT`,
 /// `Arial-BoldItalicMT`, or `Arial` followed by `,Bold`, `,Italic` or `,BoldItalic`. Arial
 /// Narrow, Arial Black, Arial Unicode MS and Arial Rounded are other fonts, numbered their own
-/// way.
+/// way. Letter case doesn't matter, `MT` included.
 fn is_arial(name: &str) -> bool {
     let (family, style) = name.split_once([',', '-', ' ']).unwrap_or((name, ""));
-    let family = family.strip_suffix("MT").unwrap_or(family);
     let style: String = style
         .chars()
         .filter(|c| !matches!(c, ',' | '-' | ' '))
         .collect();
-    let style = style.strip_suffix("MT").unwrap_or(&style);
-    family.eq_ignore_ascii_case("Arial")
+    without_mt(family).eq_ignore_ascii_case("Arial")
         && ["", "Regular", "Bold", "Italic", "BoldItalic"]
             .iter()
-            .any(|s| style.eq_ignore_ascii_case(s))
+            .any(|s| without_mt(&style).eq_ignore_ascii_case(s))
+}
+
+/// PdfCraft patch: `name` without a trailing `MT` in any letter case (Monotype's mark in
+/// PostScript names such as `ArialMT`).
+fn without_mt(name: &str) -> &str {
+    name.len()
+        .checked_sub(2)
+        .and_then(|stem| Some((name.get(..stem)?, name.get(stem..)?)))
+        .filter(|(_, suffix)| suffix.eq_ignore_ascii_case("MT"))
+        .map_or(name, |(stem, _)| stem)
 }
 
 /// PdfCraft patch: the largest CID (ISO 32000-2 §9.7.2; CIDs are at most two bytes).