From 75f646c9756634fe6bc7f94349f6496ed0fc5484 Mon Sep 17 00:00:00 2001
From: Max <me@mkor.je>
Date: Tue, 1 Oct 2024 07:59:31 +0000
Subject: [PATCH] Fix `math.stretch` not working vertically with attachments
 (#5069)

---
 crates/typst/src/math/stretch.rs                |   8 +++++++-
 tests/ref/issue-4188-lr-corner-brackets.png     | Bin 368 -> 364 bytes
 ...h.png => math-stretch-horizontal-attach.png} | Bin
 tests/ref/math-stretch-vertical-attach.png      | Bin 0 -> 493 bytes
 tests/suite/math/stretch.typ                    |  11 +++++++++--
 5 files changed, 16 insertions(+), 3 deletions(-)
 rename tests/ref/{math-stretch-attach.png => math-stretch-horizontal-attach.png} (100%)
 create mode 100644 tests/ref/math-stretch-vertical-attach.png

diff --git a/crates/typst/src/math/stretch.rs b/crates/typst/src/math/stretch.rs
index d316fa9a2..232252b99 100644
--- a/crates/typst/src/math/stretch.rs
+++ b/crates/typst/src/math/stretch.rs
@@ -73,9 +73,15 @@ pub(super) fn stretch_fragment(
         _ => return,
     };
 
-    let Some(axis) = axis.or_else(|| stretch_axis(ctx, &glyph)) else {
+    // Return if we attempt to stretch along an axis which isn't stretchable,
+    // so that the original fragment isn't modified.
+    let Some(stretch_axis) = stretch_axis(ctx, &glyph) else {
         return;
     };
+    let axis = axis.unwrap_or(stretch_axis);
+    if axis != stretch_axis {
+        return;
+    }
 
     let relative_to_size = relative_to.unwrap_or_else(|| fragment.size().get(axis));
 
diff --git a/tests/ref/issue-4188-lr-corner-brackets.png b/tests/ref/issue-4188-lr-corner-brackets.png
index 81e9ecdcd40ecf7101c256b95f6574ddd661886b..6e247908b69ad0ac40f6fbe5e83965d74ac71f8a 100644
GIT binary patch
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delta 304
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C)|E~G

diff --git a/tests/ref/math-stretch-attach.png b/tests/ref/math-stretch-horizontal-attach.png
similarity index 100%
rename from tests/ref/math-stretch-attach.png
rename to tests/ref/math-stretch-horizontal-attach.png
diff --git a/tests/ref/math-stretch-vertical-attach.png b/tests/ref/math-stretch-vertical-attach.png
new file mode 100644
index 0000000000000000000000000000000000000000..213ab89b681e5e13ec7c70c476feb4fcb440a26e
GIT binary patch
literal 493
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literal 0
HcmV?d00001

diff --git a/tests/suite/math/stretch.typ b/tests/suite/math/stretch.typ
index e6817ee5e..606967466 100644
--- a/tests/suite/math/stretch.typ
+++ b/tests/suite/math/stretch.typ
@@ -13,8 +13,8 @@ $ H stretch(=)^"define" U + p V \
   f : X stretch(arrow.hook, size: #150%)_"injective" Y \
   V stretch(->, size: #(100% + 1.5em))^("surjection") ZZ $
 
---- math-stretch-attach ---
-// Test stretch interactions with attachments.
+--- math-stretch-horizontal-attach ---
+// Test horizontal stretch interactions with attachments.
 #set page(width: auto)
 
 $stretch(stretch(=, size: #4em))_A$
@@ -28,6 +28,13 @@ $ P = Q
   U stretch(equiv)^(forall i)_"Chern-Weil" V
     stretch(equiv, size: #(120% + 2mm))^(forall i)_"Chern-Weil" W $
 
+--- math-stretch-vertical-attach ---
+// Test vertical stretch interactions with attachments.
+$arrow.t$
+$stretch(arrow.t)^"map"$
+$stretch(arrow.t, size: #2em)^"map"$
+$stretch(arrow.t, size: #200%)^"map"$
+
 --- math-stretch-horizontal ---
 // Test stretching along horizontal axis.
 #let ext(sym) = math.stretch(sym, size: 2em)