From c38558d9db86dc817e867fc9248ca260fd616d73 Mon Sep 17 00:00:00 2001
From: Said Aroua <said.aroua@bluewin.ch>
Date: Sun, 25 May 2025 15:02:34 +0200
Subject: [PATCH] Fail on empty label name (#5776)

---
 crates/typst-library/src/foundations/label.rs | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/crates/typst-library/src/foundations/label.rs b/crates/typst-library/src/foundations/label.rs
index 2f5520b1c..143da2354 100644
--- a/crates/typst-library/src/foundations/label.rs
+++ b/crates/typst-library/src/foundations/label.rs
@@ -1,7 +1,10 @@
 use ecow::{eco_format, EcoString};
 use typst_utils::{PicoStr, ResolvedPicoStr};
 
-use crate::foundations::{func, scope, ty, Repr, Str};
+use crate::{
+    diag::StrResult,
+    foundations::{bail, func, scope, ty, Repr, Str},
+};
 
 /// A label for an element.
 ///
@@ -27,7 +30,8 @@ use crate::foundations::{func, scope, ty, Repr, Str};
 /// # Syntax
 /// This function also has dedicated syntax: You can create a label by enclosing
 /// its name in angle brackets. This works both in markup and code. A label's
-/// name can contain letters, numbers, `_`, `-`, `:`, and `.`.
+/// name can contain letters, numbers, `_`, `-`, `:`, and `.`. Empty label names
+/// get rejected.
 ///
 /// Note that there is a syntactical difference when using the dedicated syntax
 /// for this function. In the code below, the `[<a>]` terminates the heading and
@@ -67,13 +71,17 @@ impl Label {
 
 #[scope]
 impl Label {
-    /// Creates a label from a string.
+    /// Creates a label from a string. Fails for empty strings.
     #[func(constructor)]
     pub fn construct(
         /// The name of the label.
         name: Str,
-    ) -> Label {
-        Self(PicoStr::intern(name.as_str()))
+    ) -> StrResult<Label> {
+        if name.is_empty() {
+            bail!("expected non-empty label name");
+        }
+
+        Ok(Self(PicoStr::intern(name.as_str())))
     }
 }