Rollup merge of #64824 - Mark-Simulacrum:no-stable-hasher-result-everywhere, r=michaelwoerister

No StableHasherResult everywhere

This removes the generic parameter on `StableHasher`, instead moving it to the call to `finish`. This has the side-effect of making all `HashStable` impls nicer, since we no longer need the verbose `<W: StableHasherResult>` that previously existed -- often forcing line wrapping.

This is done for two reasons:
 * we should avoid false "generic" dependency on the result of StableHasher
     * we don't need to codegen two/three copies of all the HashStable impls when they're transitively used to produce a fingerprint, u64, or u128. I haven't measured, but this might actually make our artifacts somewhat smaller too.
 * Easier to understand/read/write code -- the result of the stable hasher is irrelevant when writing a hash impl.

1 files changed, 2 insertions, 5 deletions

diff --git a/src/librustc_codegen_ssa/common.rs b/src/librustc_codegen_ssa/common.rs
index 6376512ca40..e3aa35ef4eb 100644
--- a/src/librustc_codegen_ssa/common.rs
+++ b/src/librustc_codegen_ssa/common.rs
@@ -109,14 +109,11 @@ pub enum TypeKind {
 //            for now we content ourselves with providing a no-op HashStable
 //            implementation for CGUs.
 mod temp_stable_hash_impls {
-    use rustc_data_structures::stable_hasher::{StableHasherResult, StableHasher,
-                                               HashStable};
+    use rustc_data_structures::stable_hasher::{StableHasher, HashStable};
     use crate::ModuleCodegen;
 
     impl<HCX, M> HashStable<HCX> for ModuleCodegen<M> {
-        fn hash_stable<W: StableHasherResult>(&self,
-                                              _: &mut HCX,
-                                              _: &mut StableHasher<W>) {
+        fn hash_stable(&self, _: &mut HCX, _: &mut StableHasher) {
             // do nothing
         }
     }