From 1d78c3ed436d70ef4fe05930903bc4b0402161b6 Mon Sep 17 00:00:00 2001
From: Laurenz <laurmaedje@gmail.com>
Date: Thu, 15 Feb 2024 11:07:07 +0100
Subject: [PATCH] Fix `h` and `v` in stack (#3423)

---
 crates/typst/src/layout/stack.rs |  19 +++++++++++++++++--
 tests/ref/bugs/1240-stack-fr.png | Bin 0 -> 1197 bytes
 tests/typ/bugs/1240-stack-fr.typ |  18 ++++++++++++++++++
 3 files changed, 35 insertions(+), 2 deletions(-)
 create mode 100644 tests/ref/bugs/1240-stack-fr.png
 create mode 100644 tests/typ/bugs/1240-stack-fr.typ

diff --git a/crates/typst/src/layout/stack.rs b/crates/typst/src/layout/stack.rs
index e1c266254..caa78264a 100644
--- a/crates/typst/src/layout/stack.rs
+++ b/crates/typst/src/layout/stack.rs
@@ -4,8 +4,8 @@ use crate::diag::SourceResult;
 use crate::engine::Engine;
 use crate::foundations::{cast, elem, Content, Packed, Resolve, StyleChain, StyledElem};
 use crate::layout::{
-    Abs, AlignElem, Axes, Axis, Dir, FixedAlignment, Fr, Fragment, Frame, LayoutMultiple,
-    Point, Regions, Size, Spacing,
+    Abs, AlignElem, Axes, Axis, Dir, FixedAlignment, Fr, Fragment, Frame, HElem,
+    LayoutMultiple, Point, Regions, Size, Spacing, VElem,
 };
 use crate::util::{Get, Numeric};
 
@@ -60,6 +60,7 @@ impl LayoutMultiple for Packed<StackElem> {
         regions: Regions,
     ) -> SourceResult<Fragment> {
         let mut layouter = StackLayouter::new(self.dir(styles), regions, styles);
+        let axis = layouter.dir.axis();
 
         // Spacing to insert before the next block.
         let spacing = self.spacing(styles);
@@ -72,6 +73,20 @@ impl LayoutMultiple for Packed<StackElem> {
                     deferred = None;
                 }
                 StackChild::Block(block) => {
+                    // Transparently handle `h`.
+                    if let (Axis::X, Some(h)) = (axis, block.to_packed::<HElem>()) {
+                        layouter.layout_spacing(*h.amount());
+                        deferred = None;
+                        continue;
+                    }
+
+                    // Transparently handle `v`.
+                    if let (Axis::Y, Some(v)) = (axis, block.to_packed::<VElem>()) {
+                        layouter.layout_spacing(*v.amount());
+                        deferred = None;
+                        continue;
+                    }
+
                     if let Some(kind) = deferred {
                         layouter.layout_spacing(kind);
                     }
diff --git a/tests/ref/bugs/1240-stack-fr.png b/tests/ref/bugs/1240-stack-fr.png
new file mode 100644
index 0000000000000000000000000000000000000000..29df5d44a58c49f0ec5407fc2b62789f54bd664f
GIT binary patch
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diff --git a/tests/typ/bugs/1240-stack-fr.typ b/tests/typ/bugs/1240-stack-fr.typ
new file mode 100644
index 000000000..fa49dce76
--- /dev/null
+++ b/tests/typ/bugs/1240-stack-fr.typ
@@ -0,0 +1,18 @@
+// This issue is sort of horrible: When you write `h(1fr)` in a `stack` instead
+// of directly `1fr`, things go awry. To fix this, we now transparently detect
+// h/v children.
+//
+// https://github.com/typst/typst/issues/1240
+
+---
+#stack(dir: ltr, [a], 1fr, [b], 1fr, [c])
+#stack(dir: ltr, [a], h(1fr), [b], h(1fr), [c])
+
+---
+#set page(height: 60pt)
+#stack(
+  dir: ltr,
+  spacing: 1fr,
+  stack([a], 1fr, [b]),
+  stack([a], v(1fr), [b]),
+)