From 43c3acdc4e601897893a5e24948444e2604edc54 Mon Sep 17 00:00:00 2001
From: Said Aroua <said.aroua@bluewin.ch>
Date: Sun, 25 May 2025 15:50:22 +0200
Subject: [PATCH] Add guard for potential empty labels from bibliography
 (#5776)

---
 crates/typst-library/src/foundations/label.rs  | 2 ++
 crates/typst-library/src/model/bibliography.rs | 9 +++++++--
 crates/typst-utils/src/pico.rs                 | 3 +++
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/crates/typst-library/src/foundations/label.rs b/crates/typst-library/src/foundations/label.rs
index 143da2354..94ddb9a7c 100644
--- a/crates/typst-library/src/foundations/label.rs
+++ b/crates/typst-library/src/foundations/label.rs
@@ -54,7 +54,9 @@ pub struct Label(PicoStr);
 
 impl Label {
     /// Creates a label from an interned string.
+    /// Callers need to ensure the given string is not empty.
     pub fn new(name: PicoStr) -> Self {
+        debug_assert!(name != PicoStr::EMPTY);
         Self(name)
     }
 
diff --git a/crates/typst-library/src/model/bibliography.rs b/crates/typst-library/src/model/bibliography.rs
index 51e3b03b0..7a0669887 100644
--- a/crates/typst-library/src/model/bibliography.rs
+++ b/crates/typst-library/src/model/bibliography.rs
@@ -313,12 +313,17 @@ impl Bibliography {
         for (source, data) in sources.0.iter().zip(data) {
             let library = decode_library(source, data)?;
             for entry in library {
-                match map.entry(Label::new(PicoStr::intern(entry.key()))) {
+                let key = entry.key();
+                if key.is_empty() {
+                    bail!("empty bibliography key found");
+                }
+
+                match map.entry(Label::new(PicoStr::intern(key))) {
                     indexmap::map::Entry::Vacant(vacant) => {
                         vacant.insert(entry);
                     }
                     indexmap::map::Entry::Occupied(_) => {
-                        duplicates.push(entry.key().into());
+                        duplicates.push(key.into());
                     }
                 }
             }
diff --git a/crates/typst-utils/src/pico.rs b/crates/typst-utils/src/pico.rs
index 2c80d37de..449039b4a 100644
--- a/crates/typst-utils/src/pico.rs
+++ b/crates/typst-utils/src/pico.rs
@@ -38,6 +38,9 @@ struct Interner {
 pub struct PicoStr(NonZeroU64);
 
 impl PicoStr {
+    /// Empty string as PicoStr
+    pub const EMPTY: PicoStr = PicoStr::constant("");
+
     /// Intern a string at runtime.
     pub fn intern(string: &str) -> PicoStr {
         // Try to use bitcode or exception representations.