Drop non-plist glyph libs instead of failing

Cargo.toml

@@ -41,6 +41,7 @@ thiserror = "2.0"
 indexmap = { version = "2.0.0", features = ["serde"] }
 base64 = "0.22"
 close_already = "0.3"
+log = "0.4"
 
 [dev-dependencies]
 failure = "0.1.6"

src/glyph/parse.rs

@@ -308,12 +308,20 @@ impl<'names> GlifParser<'names> {
         }
 
         let plist_slice = &raw_xml[start..end];
-        let dict = plist::Value::from_reader_xml(plist_slice)
-            .map_err(|_| GlifLoadError::Parse(ErrorKind::BadLib))?
-            .into_dictionary()
-            .ok_or(GlifLoadError::Parse(ErrorKind::LibMustBeDictionary))?;
+        match plist::Value::from_reader_xml(plist_slice)
+            .map_err(|_| GlifLoadError::Parse(ErrorKind::BadLib))
+            .and_then(|x| {
+                x.into_dictionary().ok_or(GlifLoadError::Parse(ErrorKind::LibMustBeDictionary))
+            }) {
+            Ok(dict) => {
+                // we used to error if this was malformed but there are a number of early UFO files
+                // in the wild that store arbitrary xml in the lib, which doesn't parse as a plist.
+                // Instead of failing to parse these files, we prefer to just skip the dicts.
+                self.glyph.lib = dict;
+            }
+            Err(e) => log::info!("glyph {} contains invalid lib: '{e}'", self.glyph.name),
+        }
 
-        self.glyph.lib = dict;
         Ok(())
     }
 

src/glyph/tests.rs

@@ -318,8 +318,9 @@ fn bad_angle() {
 }
 
 #[test]
-#[should_panic(expected = "LibMustBeDictionary")]
-fn lib_must_be_dict() {
+// in a number of older UFO files in the wild glyphs can contain dictionaries
+// with arbitrary non-plsit XML:
+fn skip_non_lib_dictionary() {
     let data = r#"
 <?xml version="1.0" encoding="UTF-8"?>
 <glyph name="period" format="2">
@@ -328,7 +329,8 @@ fn lib_must_be_dict() {
     </lib>
 </glyph>
 "#;
-    let _ = parse_glyph(data.as_bytes()).unwrap();
+    let glyph = parse_glyph(data.as_bytes()).unwrap();
+    assert!(glyph.lib.is_empty());
 }
 
 #[test]