Auto merge of #114739 - lcnr:int-infer-impls, r=compiler-errors

remove builtin `Copy` and `Clone` impl for float and int infer

it's only change is whether `{integer}: Copy` is ambiguous, this has the following properties

- these goals get proven earlier, potentially resulting in slightly better perf
- it causes inconsistent behavior and ICE if there do not exist impls for all integers, causing issues when using `#[no_core]`
- it means `Clone` has user-facing differences from other traits from `core` with the new solver because it can potentially guide inference there
- it's just very sus™ to have a builtin impl which applies during type inference but not afterwards

Author: bors

compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs

@@ -161,14 +161,12 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
     ty: Ty<'tcx>,
 ) -> Result<Vec<Ty<'tcx>>, NoSolution> {
     match *ty.kind() {
-        ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
-        | ty::FnDef(..)
-        | ty::FnPtr(_)
-        | ty::Error(_) => Ok(vec![]),
+        ty::FnDef(..) | ty::FnPtr(_) | ty::Error(_) => Ok(vec![]),
 
         // Implementations are provided in core
         ty::Uint(_)
         | ty::Int(_)
+        | ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
         | ty::Bool
         | ty::Float(_)
         | ty::Char

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -2118,14 +2118,11 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
         use self::BuiltinImplConditions::{Ambiguous, None, Where};
 
         match *self_ty.kind() {
-            ty::Infer(ty::IntVar(_))
-            | ty::Infer(ty::FloatVar(_))
-            | ty::FnDef(..)
-            | ty::FnPtr(_)
-            | ty::Error(_) => Where(ty::Binder::dummy(Vec::new())),
+            ty::FnDef(..) | ty::FnPtr(_) | ty::Error(_) => Where(ty::Binder::dummy(Vec::new())),
 
             ty::Uint(_)
             | ty::Int(_)
+            | ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
             | ty::Bool
             | ty::Float(_)
             | ty::Char