Fix glob import ICE in rustdoc JSON format

Author: GuillaumeGomez

src/librustdoc/clean/types.rs

@@ -2161,8 +2161,12 @@ impl Path {
         self.res.def_id()
     }
 
+    pub(crate) fn last_opt(&self) -> Option<Symbol> {
+        self.segments.last().map(|s| s.name)
+    }
+
     pub(crate) fn last(&self) -> Symbol {
-        self.segments.last().expect("segments were empty").name
+        self.last_opt().expect("segments were empty")
     }
 
     pub(crate) fn whole_name(&self) -> String {

src/librustdoc/json/conversions.rs

@@ -663,7 +663,12 @@ impl FromWithTcx<clean::Import> for Import {
             },
             Glob => Import {
                 source: import.source.path.whole_name(),
-                name: import.source.path.last().to_string(),
+                name: import
+                    .source
+                    .path
+                    .last_opt()
+                    .unwrap_or_else(|| Symbol::intern("*"))
+                    .to_string(),
                 id: import.source.did.map(ItemId::from).map(|i| from_item_id(i, tcx)),
                 glob: true,
             },