Don't hash non-fresh Ty::Infer or RegionKind::Infer

Author: compiler-errors

compiler/rustc_middle/src/ty/context.rs

@@ -198,9 +198,11 @@ impl<'tcx> CtxtInterners<'tcx> {
                 .intern(kind, |kind| {
                     let flags = super::flags::FlagComputation::for_kind(&kind);
 
-                    // It's impossible to hash inference regions (and will ICE), so we don't need to try to cache them.
+                    // It's impossible to hash inference variables (and will ICE), so we don't need to try to cache them.
                     // Without incremental, we rarely stable-hash types, so let's not do it proactively.
-                    let stable_hash = if flags.flags.intersects(TypeFlags::HAS_RE_INFER)
+                    let stable_hash = if flags
+                        .flags
+                        .intersects(TypeFlags::HAS_RE_INFER | TypeFlags::HAS_TY_INFER)
                         || sess.opts.incremental.is_none()
                     {
                         Fingerprint::ZERO

compiler/rustc_type_ir/src/lib.rs

@@ -675,9 +675,9 @@ impl<CTX> HashStable<CTX> for InferTy {
         use InferTy::*;
         discriminant(self).hash_stable(ctx, hasher);
         match self {
-            TyVar(v) => v.as_u32().hash_stable(ctx, hasher),
-            IntVar(v) => v.index.hash_stable(ctx, hasher),
-            FloatVar(v) => v.index.hash_stable(ctx, hasher),
+            TyVar(_) | IntVar(_) | FloatVar(_) => {
+                panic!("inference variables should not be hashed: {self:?}")
+            }
             FreshTy(v) | FreshIntTy(v) | FreshFloatTy(v) => v.hash_stable(ctx, hasher),
         }
     }

compiler/rustc_type_ir/src/sty.rs

@@ -1332,8 +1332,8 @@ where
             RePlaceholder(p) => {
                 p.hash_stable(hcx, hasher);
             }
-            ReVar(reg) => {
-                reg.hash_stable(hcx, hasher);
+            ReVar(_) => {
+                panic!("region variables should not be hashed: {self:?}")
             }
         }
     }