Use the full Fingerprint when stringifying Svh

compiler/rustc_data_structures/src/fingerprint.rs

@@ -64,6 +64,11 @@ impl Fingerprint {
         )
     }
 
+    #[inline]
+    pub(crate) fn as_u128(self) -> u128 {
+        u128::from(self.1) << 64 | u128::from(self.0)
+    }
+
     // Combines two hashes in an order independent way. Make sure this is what
     // you want.
     #[inline]

compiler/rustc_data_structures/src/svh.rs

@@ -23,18 +23,18 @@ impl Svh {
         Svh { hash }
     }
 
-    pub fn as_u64(&self) -> u64 {
-        self.hash.to_smaller_hash().as_u64()
+    pub fn as_u128(self) -> u128 {
+        self.hash.as_u128()
     }
 
-    pub fn to_string(&self) -> String {
-        format!("{:016x}", self.hash.to_smaller_hash())
+    pub fn to_hex(self) -> String {
+        format!("{:032x}", self.hash.as_u128())
     }
 }
 
 impl fmt::Display for Svh {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad(&self.to_string())
+        f.pad(&self.to_hex())
     }
 }
 

compiler/rustc_incremental/src/persist/fs.rs

@@ -346,7 +346,7 @@ pub fn finalize_session_directory(sess: &Session, svh: Option<Svh>) {
     let mut new_sub_dir_name = String::from(&old_sub_dir_name[..=dash_indices[2]]);
 
     // Append the svh
-    base_n::push_str(svh.as_u64() as u128, INT_ENCODE_BASE, &mut new_sub_dir_name);
+    base_n::push_str(svh.as_u128(), INT_ENCODE_BASE, &mut new_sub_dir_name);
 
     // Create the full path
     let new_path = incr_comp_session_dir.parent().unwrap().join(new_sub_dir_name);