Remove a fishy Clone impl

compiler/rustc_data_structures/src/sync.rs

@@ -481,14 +481,6 @@ impl<T: Default> Default for Lock<T> {
     }
 }
 
-// FIXME: Probably a bad idea
-impl<T: Clone> Clone for Lock<T> {
-    #[inline]
-    fn clone(&self) -> Self {
-        Lock::new(self.borrow().clone())
-    }
-}
-
 #[derive(Debug, Default)]
 pub struct RwLock<T>(InnerRwLock<T>);
 

compiler/rustc_middle/src/mir/interpret/mod.rs

@@ -263,7 +263,8 @@ impl AllocDecodingState {
     }
 
     pub fn new(data_offsets: Vec<u32>) -> Self {
-        let decoding_state = vec![Lock::new(State::Empty); data_offsets.len()];
+        let decoding_state =
+            std::iter::repeat_with(|| Lock::new(State::Empty)).take(data_offsets.len()).collect();
 
         Self { decoding_state, data_offsets }
     }

compiler/rustc_query_system/src/cache.rs

@@ -7,11 +7,16 @@ use rustc_data_structures::sync::Lock;
 
 use std::hash::Hash;
 
-#[derive(Clone)]
 pub struct Cache<Key, Value> {
     hashmap: Lock<FxHashMap<Key, WithDepNode<Value>>>,
 }
 
+impl<Key: Clone, Value: Clone> Clone for Cache<Key, Value> {
+    fn clone(&self) -> Self {
+        Self { hashmap: Lock::new(self.hashmap.borrow().clone()) }
+    }
+}
+
 impl<Key, Value> Default for Cache<Key, Value> {
     fn default() -> Self {
         Self { hashmap: Default::default() }

compiler/rustc_span/src/lib.rs

@@ -1318,7 +1318,6 @@ pub struct SourceFileDiffs {
 }
 
 /// A single source in the [`SourceMap`].
-#[derive(Clone)]
 pub struct SourceFile {
     /// The name of the file that the source came from. Source that doesn't
     /// originate from files has names between angle brackets by convention
@@ -1349,6 +1348,25 @@ pub struct SourceFile {
     pub cnum: CrateNum,
 }
 
+impl Clone for SourceFile {
+    fn clone(&self) -> Self {
+        Self {
+            name: self.name.clone(),
+            src: self.src.clone(),
+            src_hash: self.src_hash.clone(),
+            external_src: Lock::new(self.external_src.borrow().clone()),
+            start_pos: self.start_pos.clone(),
+            end_pos: self.end_pos.clone(),
+            lines: Lock::new(self.lines.borrow().clone()),
+            multibyte_chars: self.multibyte_chars.clone(),
+            non_narrow_chars: self.non_narrow_chars.clone(),
+            normalized_pos: self.normalized_pos.clone(),
+            name_hash: self.name_hash.clone(),
+            cnum: self.cnum.clone(),
+        }
+    }
+}
+
 impl<S: Encoder> Encodable<S> for SourceFile {
     fn encode(&self, s: &mut S) {
         self.name.encode(s);