Auto merge of #125958 - BoxyUwU:remove_const_ty, r=lcnr

Remove the `ty` field from type system `Const`s

Fixes #125556
Fixes #122908

Part of the work on `adt_const_params`/`generic_const_param_types`/`min_generic_const_exprs`/generally making the compiler nicer. cc rust-lang/project-const-generics#44

Please review commit-by-commit otherwise I wasted a lot of time not just squashing this into a giant mess (and also it'll be SO much nicer because theres a lot of fluff changes mixed in with other more careful changes if looking via File Changes

---

Why do this?
- The `ty` field keeps causing ICEs and weird behaviour due to it either being treated as "part of the const" or it being forgotten about leading to ICEs.
- As we move forward with `adt_const_params` and a potential `min_generic_const_exprs` it's going to become more complex to actually lower the correct `Ty<'tcx>`
- It muddles the idea behind how we check `Const` arguments have the correct type. By having the `ty` field it may seem like we ought to be relating it when we relate two types, or that its generally important information about the `Const`.
- Brings the compiler more in line with `a-mir-formality` as that also tracks the type of type system `Const`s via `ConstArgHasType` bounds in the env instead of on the `Const` itself.
- A lot of stuff is a lot nicer when you dont have to pass around the type of a const lol. Everywhere we construct `Const` is now significantly nicer :sweat_smile:

See #125671's description for some more information about the `ty` field

---

General summary of changes in this PR:

- Add `Ty` to `ConstKind::Value` as otherwise there is no way to implement `ConstArgHasType` to ensure that const arguments are correctly typed for the parameter when we stop creating anon consts for all const args. It's also just incredibly difficult/annoying to thread the correct `Ty` around to a bunch of ctfe functions otherwise.
-  Fully implement `ConstArgHasType` in both the old and new solver. Since it now has no reliance on the `ty` field it serves its originally intended purpose of being able to act as a double check that trait vs impls have correctly typed const parameters. It also will now be able to be responsible for checking types of const arguments to parameters under `min_generic_const_exprs`.
- Add `Ty` to `mir::Const::Ty`. I dont have a great understanding of why mir constants are setup like this to be honest. Regardless they need to be able to determine the type of the const and the easiest way to make this happen was to simply store the `Ty` along side the `ty::Const`. Maybe we can do better here in the future but I'd have to spend way more time looking at everywhere we use `mir::Const`.
- rustdoc has its own `Const` which also has a `ty` field. It was relatively easy to remove this.

---

r? `@lcnr` `@compiler-errors`

8 files changed, 15 insertions, 11 deletions

diff --git a/src/tools/clippy/clippy_lints/src/large_const_arrays.rs b/src/tools/clippy/clippy_lints/src/large_const_arrays.rs
index b561054b582..77d05020c82 100644
--- a/src/tools/clippy/clippy_lints/src/large_const_arrays.rs
+++ b/src/tools/clippy/clippy_lints/src/large_const_arrays.rs
@@ -54,7 +54,7 @@ impl<'tcx> LateLintPass<'tcx> for LargeConstArrays {
             && generics.params.is_empty() && !generics.has_where_clause_predicates
             && let ty = cx.tcx.type_of(item.owner_id).instantiate_identity()
             && let ty::Array(element_type, cst) = ty.kind()
-            && let ConstKind::Value(ty::ValTree::Leaf(element_count)) = cst.kind()
+            && let ConstKind::Value(_, ty::ValTree::Leaf(element_count)) = cst.kind()
             && let Ok(element_count) = element_count.try_to_target_usize(cx.tcx)
             && let Ok(element_size) = cx.layout_of(*element_type).map(|l| l.size.bytes())
             && self.maximum_allowed_size < u128::from(element_count) * u128::from(element_size)
diff --git a/src/tools/clippy/clippy_lints/src/large_stack_arrays.rs b/src/tools/clippy/clippy_lints/src/large_stack_arrays.rs
index 208d1bb6e68..f0f3f53647b 100644
--- a/src/tools/clippy/clippy_lints/src/large_stack_arrays.rs
+++ b/src/tools/clippy/clippy_lints/src/large_stack_arrays.rs
@@ -64,7 +64,7 @@ impl<'tcx> LateLintPass<'tcx> for LargeStackArrays {
         if let ExprKind::Repeat(_, _) | ExprKind::Array(_) = expr.kind
             && !self.is_from_vec_macro(cx, expr.span)
             && let ty::Array(element_type, cst) = cx.typeck_results().expr_ty(expr).kind()
-            && let ConstKind::Value(ty::ValTree::Leaf(element_count)) = cst.kind()
+            && let ConstKind::Value(_, ty::ValTree::Leaf(element_count)) = cst.kind()
             && let Ok(element_count) = element_count.try_to_target_usize(cx.tcx)
             && let Ok(element_size) = cx.layout_of(*element_type).map(|l| l.size.bytes())
             && !cx.tcx.hir().parent_iter(expr.hir_id).any(|(_, node)| {
diff --git a/src/tools/clippy/clippy_lints/src/matches/overlapping_arms.rs b/src/tools/clippy/clippy_lints/src/matches/overlapping_arms.rs
index 8199366d175..45b375dbe3d 100644
--- a/src/tools/clippy/clippy_lints/src/matches/overlapping_arms.rs
+++ b/src/tools/clippy/clippy_lints/src/matches/overlapping_arms.rs
@@ -37,14 +37,14 @@ fn all_ranges<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>], ty: Ty<'tcx>)
                         Some(lhs) => constant(cx, cx.typeck_results(), lhs)?,
                         None => {
                             let min_val_const = ty.numeric_min_val(cx.tcx)?;
-                            mir_to_const(cx, mir::Const::from_ty_const(min_val_const, cx.tcx))?
+                            mir_to_const(cx, mir::Const::from_ty_const(min_val_const, ty, cx.tcx))?
                         },
                     };
                     let rhs_const = match rhs {
                         Some(rhs) => constant(cx, cx.typeck_results(), rhs)?,
                         None => {
                             let max_val_const = ty.numeric_max_val(cx.tcx)?;
-                            mir_to_const(cx, mir::Const::from_ty_const(max_val_const, cx.tcx))?
+                            mir_to_const(cx, mir::Const::from_ty_const(max_val_const, ty, cx.tcx))?
                         },
                     };
                     let lhs_val = lhs_const.int_value(cx, ty)?;
diff --git a/src/tools/clippy/clippy_lints/src/zero_repeat_side_effects.rs b/src/tools/clippy/clippy_lints/src/zero_repeat_side_effects.rs
index 143fecdd237..848b49130dc 100644
--- a/src/tools/clippy/clippy_lints/src/zero_repeat_side_effects.rs
+++ b/src/tools/clippy/clippy_lints/src/zero_repeat_side_effects.rs
@@ -55,7 +55,7 @@ impl LateLintPass<'_> for ZeroRepeatSideEffects {
             inner_check(cx, expr, inner_expr, true);
         } else if let ExprKind::Repeat(inner_expr, _) = expr.kind
             && let ty::Array(_, cst) = cx.typeck_results().expr_ty(expr).kind()
-            && let ConstKind::Value(ty::ValTree::Leaf(element_count)) = cst.kind()
+            && let ConstKind::Value(_, ty::ValTree::Leaf(element_count)) = cst.kind()
             && let Ok(element_count) = element_count.try_to_target_usize(cx.tcx)
             && element_count == 0
         {
diff --git a/src/tools/clippy/clippy_utils/src/lib.rs b/src/tools/clippy/clippy_utils/src/lib.rs
index b10830b24e1..1147dce6215 100644
--- a/src/tools/clippy/clippy_utils/src/lib.rs
+++ b/src/tools/clippy/clippy_utils/src/lib.rs
@@ -1534,7 +1534,7 @@ pub fn is_range_full(cx: &LateContext<'_>, expr: &Expr<'_>, container_path: Opti
             if let rustc_ty::Adt(_, subst) = ty.kind()
                 && let bnd_ty = subst.type_at(0)
                 && let Some(min_val) = bnd_ty.numeric_min_val(cx.tcx)
-                && let Some(min_const) = mir_to_const(cx, Const::from_ty_const(min_val, cx.tcx))
+                && let Some(min_const) = mir_to_const(cx, Const::from_ty_const(min_val, bnd_ty, cx.tcx))
                 && let Some(start_const) = constant(cx, cx.typeck_results(), start)
             {
                 start_const == min_const
@@ -1547,7 +1547,7 @@ pub fn is_range_full(cx: &LateContext<'_>, expr: &Expr<'_>, container_path: Opti
                 if let rustc_ty::Adt(_, subst) = ty.kind()
                     && let bnd_ty = subst.type_at(0)
                     && let Some(max_val) = bnd_ty.numeric_max_val(cx.tcx)
-                    && let Some(max_const) = mir_to_const(cx, Const::from_ty_const(max_val, cx.tcx))
+                    && let Some(max_const) = mir_to_const(cx, Const::from_ty_const(max_val, bnd_ty, cx.tcx))
                     && let Some(end_const) = constant(cx, cx.typeck_results(), end)
                 {
                     end_const == max_const
diff --git a/src/tools/jsondoclint/src/item_kind.rs b/src/tools/jsondoclint/src/item_kind.rs
index 9bd04e11cb3..525de03bbce 100644
--- a/src/tools/jsondoclint/src/item_kind.rs
+++ b/src/tools/jsondoclint/src/item_kind.rs
@@ -150,7 +150,7 @@ impl Kind {
             ItemEnum::Impl(_) => Impl,
             ItemEnum::TypeAlias(_) => TypeAlias,
             ItemEnum::OpaqueTy(_) => OpaqueTy,
-            ItemEnum::Constant(_) => Constant,
+            ItemEnum::Constant { .. } => Constant,
             ItemEnum::Static(_) => Static,
             ItemEnum::Macro(_) => Macro,
             ItemEnum::ProcMacro(_) => ProcMacro,
diff --git a/src/tools/jsondoclint/src/validator.rs b/src/tools/jsondoclint/src/validator.rs
index 904c2b614f3..5e35ce242fe 100644
--- a/src/tools/jsondoclint/src/validator.rs
+++ b/src/tools/jsondoclint/src/validator.rs
@@ -101,7 +101,10 @@ impl<'a> Validator<'a> {
                 ItemEnum::Impl(x) => self.check_impl(x, id),
                 ItemEnum::TypeAlias(x) => self.check_type_alias(x),
                 ItemEnum::OpaqueTy(x) => self.check_opaque_ty(x),
-                ItemEnum::Constant(x) => self.check_constant(x),
+                ItemEnum::Constant { type_, const_ } => {
+                    self.check_type(type_);
+                    self.check_constant(const_);
+                }
                 ItemEnum::Static(x) => self.check_static(x),
                 ItemEnum::ForeignType => {} // nop
                 ItemEnum::Macro(x) => self.check_macro(x),
@@ -231,8 +234,8 @@ impl<'a> Validator<'a> {
         self.check_generics(&x.generics);
     }
 
-    fn check_constant(&mut self, x: &'a Constant) {
-        self.check_type(&x.type_);
+    fn check_constant(&mut self, _x: &'a Constant) {
+        // nop
     }
 
     fn check_static(&mut self, x: &'a Static) {
diff --git a/src/tools/miri/src/intrinsics/simd.rs b/src/tools/miri/src/intrinsics/simd.rs
index ed0c30e2a11..8ba4964ff89 100644
--- a/src/tools/miri/src/intrinsics/simd.rs
+++ b/src/tools/miri/src/intrinsics/simd.rs
@@ -590,6 +590,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     .expect_const()
                     .eval(*this.tcx, this.param_env(), this.tcx.span)
                     .unwrap()
+                    .1
                     .unwrap_branch();
                 let index_len = index.len();