1 files changed, 19 insertions, 0 deletions
diff --git a/compiler/rustc_data_structures/src/stable_hasher.rs b/compiler/rustc_data_structures/src/stable_hasher.rs
index 3da35178957..9c09a7f5f82 100644
--- a/compiler/rustc_data_structures/src/stable_hasher.rs
+++ b/compiler/rustc_data_structures/src/stable_hasher.rs
@@ -583,3 +583,22 @@ fn stable_hash_reduce<HCX, I, C, F>(
         }
     }
 }
+
+#[derive(PartialEq, Eq, Clone, Copy, Hash, Debug)]
+pub enum NodeIdHashingMode {
+    Ignore,
+    HashDefPath,
+}
+
+/// Controls what data we do or not not hash.
+/// Whenever a `HashStable` implementation caches its
+/// result, it needs to include `HashingControls` as part
+/// of the key, to ensure that is does not produce an incorrect
+/// result (for example, using a `Fingerprint` produced while
+/// hashing `Span`s when a `Fingeprint` without `Span`s is
+/// being requested)
+#[derive(Clone, Hash, Eq, PartialEq, Debug)]
+pub struct HashingControls {
+    pub hash_spans: bool,
+    pub node_id_hashing_mode: NodeIdHashingMode,
+}