Auto merge of #142223 - compiler-errors:perf-wf, r=<try>

[perf] Fast path for WF goals in new solver

I'll clean this up obviously, but I don't want to do that if this is worthless.

Author: rust-bors[bot]

compiler/rustc_trait_selection/src/solve/delegate.rs

@@ -136,6 +136,54 @@ impl<'tcx> rustc_next_trait_solver::delegate::SolverDelegate for SolverDelegate<
                     None
                 }
             }
+            ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(arg)) => match arg.kind() {
+                ty::TermKind::Ty(ty) => match self.shallow_resolve(ty).kind() {
+                    ty::Bool
+                    | ty::Char
+                    | ty::Int(_)
+                    | ty::Uint(_)
+                    | ty::Float(_)
+                    | ty::Str
+                    | ty::Never
+                    | ty::Param(_)
+                    | ty::Placeholder(_) => Some(Certainty::Yes),
+
+                    ty::Infer(infer) => match infer {
+                        ty::TyVar(_) => Some(Certainty::AMBIGUOUS),
+                        ty::IntVar(_) | ty::FloatVar(_) => Some(Certainty::Yes),
+                        ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => unreachable!(),
+                    },
+
+                    ty::Adt(_, _)
+                    | ty::Foreign(_)
+                    | ty::Array(_, _)
+                    | ty::Pat(_, _)
+                    | ty::Slice(_)
+                    | ty::RawPtr(..)
+                    | ty::Ref(..)
+                    | ty::FnDef(..)
+                    | ty::FnPtr(..)
+                    | ty::UnsafeBinder(..)
+                    | ty::Dynamic(..)
+                    | ty::Closure(..)
+                    | ty::CoroutineClosure(..)
+                    | ty::Coroutine(..)
+                    | ty::CoroutineWitness(..)
+                    | ty::Tuple(_)
+                    | ty::Alias(..)
+                    | ty::Bound(..)
+                    | ty::Error(_) => None,
+                },
+                ty::TermKind::Const(ct) => match self.shallow_resolve_const(ct).kind() {
+                    ty::ConstKind::Param(_) | ty::ConstKind::Placeholder(_) => Some(Certainty::Yes),
+                    ty::ConstKind::Infer(_) => Some(Certainty::AMBIGUOUS),
+                    ty::ConstKind::Bound(..)
+                    | ty::ConstKind::Unevaluated(..)
+                    | ty::ConstKind::Value(_)
+                    | ty::ConstKind::Error(_)
+                    | ty::ConstKind::Expr(_) => None,
+                },
+            },
             _ => None,
         }
     }