Fix math.lr size argument not being applied to enclosed math.mid (#5050)

crates/typst/src/math/lr.rs

@@ -3,7 +3,9 @@ use unicode_math_class::MathClass;
 use crate::diag::SourceResult;
 use crate::foundations::{elem, func, Content, NativeElement, Packed, Smart, StyleChain};
 use crate::layout::{Abs, Axis, Em, Length, Rel};
-use crate::math::{stretch_fragment, LayoutMath, MathContext, MathFragment, Scaled};
+use crate::math::{
+    stretch_fragment, EquationElem, LayoutMath, MathContext, MathFragment, Scaled,
+};
 use crate::text::TextElem;
 
 /// How much less high scaled delimiters can be than what they wrap.
@@ -21,13 +23,9 @@ pub struct LrElem {
     /// The delimited content, including the delimiters.
     #[required]
     #[parse(
-        let mut body = Content::empty();
-        for (i, arg) in args.all::<Content>()?.into_iter().enumerate() {
-            if i > 0 {
-                body += TextElem::packed(',');
-            }
-            body += arg;
-        }
+        let mut arguments = args.all::<Content>()?.into_iter();
+        let mut body = arguments.next().unwrap_or_default();
+        arguments.for_each(|arg| body += TextElem::packed(',') + arg);
         body
     )]
     pub body: Content,
@@ -37,9 +35,16 @@ impl LayoutMath for Packed<LrElem> {
     #[typst_macros::time(name = "math.lr", span = self.span())]
     fn layout_math(&self, ctx: &mut MathContext, styles: StyleChain) -> SourceResult<()> {
         let mut body = self.body();
-        if let Some(elem) = body.to_packed::<LrElem>() {
-            if elem.size(styles).is_auto() {
-                body = elem.body();
+
+        // Extract from an EquationElem.
+        if let Some(equation) = body.to_packed::<EquationElem>() {
+            body = equation.body();
+        }
+
+        // Extract implicit LrElem.
+        if let Some(lr) = body.to_packed::<LrElem>() {
+            if lr.size(styles).is_auto() {
+                body = lr.body();
             }
         }
 

tests/suite/math/delimited.typ

@@ -52,6 +52,31 @@ $ { x mid(|) sum_(i=1)^oo phi_i (x) < 1 } \
       mid(bar.v.double)
     floor(hat(I) mid(slash) { dot mid(|) dot } mid(|) I/n) } $
 
+--- math-lr-mid-size ---
+// Test mid when lr size is set.
+#set page(width: auto)
+
+$ lr({ A mid(|) integral }) quad
+  lr(size: #1em, { A mid(|) integral }) quad
+  lr(size: #(1em+20%), { A mid(|) integral }) \
+
+  lr(] A mid(|) integral ]) quad
+  lr(size: #1em, ] A mid(|) integral ]) quad
+  lr(size: #(1em+20%), ] A mid(|) integral ]) \
+
+  lr(( A mid(|) integral ]) quad
+  lr(size: #1em, ( A mid(|) integral ]) quad
+  lr(size: #(1em+20%), ( A mid(|) integral ]) $
+
+--- math-lr-mid-size-nested-equation ---
+// Test mid size when lr size is set, when nested in an equation.
+#set page(width: auto)
+
+#let body = ${ A mid(|) integral }$
+$ lr(body) quad
+  lr(size: #1em, body) quad
+  lr(size: #(1em+20%), body) $
+
 --- math-lr-unbalanced ---
 // Test unbalanced delimiters.
 $ 1/(2 (x) $
@@ -63,6 +88,16 @@ $ 1/(2 y (x) (2(3)) $
 // and immediately before the closing.
 $ [#h(1em, weak: true)A(dif x, f(x) dif x)sum#h(1em, weak: true)] $
 
+--- math-lr-nested ---
+// Test nested lr calls.
+#let body1 = math.lr($|$, size: 4em)
+#let body2 = $lr(|, size: #4em)$
+
+$lr(|, size: #2em)$
+$lr(lr(|, size: #4em), size: #50%)$
+$lr(body1, size: #50%)$
+$lr(body2, size: #50%)$
+
 --- issue-4188-lr-corner-brackets ---
 // Test positioning of U+231C to U+231F
 $⌜a⌟⌞b⌝$ = $⌜$$a$$⌟$$⌞$$b$$⌝$