From 76c5ca051e9c784e919e0b85155d147388e8e3d7 Mon Sep 17 00:00:00 2001
From: T0mstone <39707032+T0mstone@users.noreply.github.com>
Date: Mon, 27 Nov 2023 16:03:11 +0100
Subject: [PATCH] Fix trailing comma of function call in math mode (#2772)

---
 crates/typst-syntax/src/ast.rs |  10 ++++++++++
 crates/typst/src/eval/call.rs  |   5 +++++
 tests/ref/math/call.png        | Bin 0 -> 1972 bytes
 tests/typ/math/call.typ        |   7 +++++++
 4 files changed, 22 insertions(+)
 create mode 100644 tests/ref/math/call.png
 create mode 100644 tests/typ/math/call.typ

diff --git a/crates/typst-syntax/src/ast.rs b/crates/typst-syntax/src/ast.rs
index 09157bbd1..df865906e 100644
--- a/crates/typst-syntax/src/ast.rs
+++ b/crates/typst-syntax/src/ast.rs
@@ -1571,6 +1571,16 @@ impl<'a> Args<'a> {
     pub fn items(self) -> impl DoubleEndedIterator<Item = Arg<'a>> {
         self.0.children().filter_map(SyntaxNode::cast)
     }
+
+    /// Whether there is a comma at the end.
+    pub fn trailing_comma(self) -> bool {
+        self.0
+            .children()
+            .rev()
+            .skip(1)
+            .find(|n| !n.kind().is_trivia())
+            .is_some_and(|n| n.kind() == SyntaxKind::Comma)
+    }
 }
 
 /// An argument to a function call.
diff --git a/crates/typst/src/eval/call.rs b/crates/typst/src/eval/call.rs
index a57cb1127..357d5e485 100644
--- a/crates/typst/src/eval/call.rs
+++ b/crates/typst/src/eval/call.rs
@@ -26,6 +26,8 @@ impl Eval for ast::FuncCall<'_> {
         let in_math = in_math(callee);
         let callee_span = callee.span();
         let args = self.args();
+        let trailing_comma = args.trailing_comma();
+
         if vm.engine.route.exceeding() {
             bail!(span, "maximum function call depth exceeded");
         }
@@ -133,6 +135,9 @@ impl Eval for ast::FuncCall<'_> {
                 }
                 body += arg;
             }
+            if trailing_comma {
+                body += TextElem::packed(',');
+            }
             return Ok(Value::Content(
                 callee.display().spanned(callee_span)
                     + LrElem::new(TextElem::packed('(') + body + TextElem::packed(')'))
diff --git a/tests/ref/math/call.png b/tests/ref/math/call.png
new file mode 100644
index 0000000000000000000000000000000000000000..907a1a2be4a699e22e45e9bfa9d9df98ad46a865
GIT binary patch
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diff --git a/tests/typ/math/call.typ b/tests/typ/math/call.typ
new file mode 100644
index 000000000..0fce16279
--- /dev/null
+++ b/tests/typ/math/call.typ
@@ -0,0 +1,7 @@
+// Test function calls that aren't typst functions
+
+---
+$ pi(a) $
+$ pi(a,) $
+$ pi(a,b) $
+$ pi(a,b,) $