Auto merge of #88499 - eddyb:layout-off, r=nagisa

Provide `layout_of` automatically (given tcx + param_env + error handling).

After #88337, there's no longer any uses of `LayoutOf` within `rustc_target` itself, so I realized I could move the trait to `rustc_middle::ty::layout` and redesign it a bit.

This is similar to #88338 (and supersedes it), but at no ergonomic loss, since there's no funky `C: LayoutOf<Ty = Ty>` -> `Ty: TyAbiInterface<C>` generic `impl` chain, and each `LayoutOf` still corresponds to one `impl` (of `LayoutOfHelpers`) for the specific context.

After this PR, this is what's needed to get `trait LayoutOf` (with the `layout_of` method) implemented on some context type:
* `TyCtxt`, via `HasTyCtxt`
* `ParamEnv`, via `HasParamEnv`
* a way to transform `LayoutError`s into the desired error type
  * an error type of `!` can be paired with having `cx.layout_of(...)` return `TyAndLayout` *without* `Result<...>` around it, such as used by codegen
  * this is done through a new `LayoutOfHelpers` trait (and so is specifying the type of `cx.layout_of(...)`)

When going through this path (and not bypassing it with a manual `impl` of `LayoutOf`), the end result is that only the error case can be customized, the query itself and the success paths are guaranteed to be uniform.

(**EDIT**: just noticed that because of the supertrait relationship, you cannot actually implement `LayoutOf` yourself, the blanket `impl` fully covers all possible context types that could ever implement it)

Part of the motivation for this shape of API is that I've been working on querifying `FnAbi::of_*`, and what I want/need to introduce for that looks a lot like the setup in this PR - in particular, it's harder to express the `FnAbi` methods in `rustc_target`, since they're much more tied to `rustc` concepts.

r? `@nagisa` cc `@oli-obk` `@bjorn3`

clippy_lints/src/casts/cast_ptr_alignment.rs

@@ -3,9 +3,9 @@
 use if_chain::if_chain;
 use rustc_hir::{Expr, ExprKind, GenericArg};
 use rustc_lint::LateContext;
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, Ty};
 use rustc_span::symbol::sym;
-use rustc_target::abi::LayoutOf;
 
 use super::CAST_PTR_ALIGNMENT;
 

clippy_lints/src/escape.rs

@@ -5,11 +5,11 @@
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::mir::FakeReadCause;
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, TraitRef, Ty};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;
 use rustc_span::symbol::kw;
-use rustc_target::abi::LayoutOf;
 use rustc_target::spec::abi::Abi;
 use rustc_typeck::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
 
@@ -171,7 +171,8 @@ fn mutate(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId) {
                 // skip if there is a `self` parameter binding to a type
                 // that contains `Self` (i.e.: `self: Box<Self>`), see #4804
                 if let Some(trait_self_ty) = self.trait_self_ty {
-                    if map.name(cmt.hir_id) == kw::SelfLower && contains_ty(self.cx.tcx, cmt.place.ty(), trait_self_ty) {
+                    if map.name(cmt.hir_id) == kw::SelfLower && contains_ty(self.cx.tcx, cmt.place.ty(), trait_self_ty)
+                    {
                         return;
                     }
                 }

clippy_lints/src/invalid_upcast_comparisons.rs

@@ -2,10 +2,10 @@
 
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, IntTy, UintTy};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::Span;
-use rustc_target::abi::LayoutOf;
 
 use clippy_utils::comparisons::Rel;
 use clippy_utils::consts::{constant, Constant};

clippy_lints/src/large_const_arrays.rs

@@ -1,10 +1,10 @@
-use crate::rustc_target::abi::LayoutOf;
 use clippy_utils::diagnostics::span_lint_and_then;
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::{Item, ItemKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::mir::interpret::ConstValue;
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, ConstKind};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::{BytePos, Pos, Span};

clippy_lints/src/large_enum_variant.rs

@@ -6,8 +6,8 @@
 use rustc_hir::{Item, ItemKind, VariantData};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::lint::in_external_macro;
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
-use rustc_target::abi::LayoutOf;
 
 declare_clippy_lint! {
     /// ### What it does

clippy_lints/src/large_stack_arrays.rs

@@ -4,11 +4,10 @@
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::mir::interpret::ConstValue;
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, ConstKind};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 
-use crate::rustc_target::abi::LayoutOf;
-
 declare_clippy_lint! {
     /// ### What it does
     /// Checks for local arrays that may be too large.

clippy_lints/src/methods/manual_saturating_arithmetic.rs

@@ -6,7 +6,7 @@
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_lint::LateContext;
-use rustc_target::abi::LayoutOf;
+use rustc_middle::ty::layout::LayoutOf;
 
 pub fn check(
     cx: &LateContext<'_>,

clippy_lints/src/pass_by_ref_or_value.rs

@@ -13,10 +13,10 @@
 use rustc_hir::{BindingAnnotation, Body, FnDecl, HirId, Impl, ItemKind, MutTy, Mutability, Node, PatKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::{sym, Span};
-use rustc_target::abi::LayoutOf;
 use rustc_target::spec::abi::Abi;
 use rustc_target::spec::Target;
 

clippy_lints/src/types/vec_box.rs

@@ -5,9 +5,9 @@
 use rustc_errors::Applicability;
 use rustc_hir::{self as hir, def_id::DefId, GenericArg, QPath, TyKind};
 use rustc_lint::LateContext;
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::TypeFoldable;
 use rustc_span::symbol::sym;
-use rustc_target::abi::LayoutOf;
 use rustc_typeck::hir_ty_to_ty;
 
 use super::VEC_BOX;

clippy_lints/src/vec.rs

@@ -1,4 +1,3 @@
-use crate::rustc_target::abi::LayoutOf;
 use clippy_utils::consts::{constant, Constant};
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::higher;
@@ -8,6 +7,7 @@
 use rustc_errors::Applicability;
 use rustc_hir::{BorrowKind, Expr, ExprKind, Mutability};
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;

clippy_lints/src/zero_sized_map_values.rs

@@ -3,10 +3,10 @@
 use if_chain::if_chain;
 use rustc_hir::{self as hir, HirId, ItemKind, Node};
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::layout::LayoutOf as _;
 use rustc_middle::ty::{Adt, Ty, TypeFoldable};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::sym;
-use rustc_target::abi::LayoutOf as _;
 use rustc_typeck::hir_ty_to_ty;
 
 declare_clippy_lint! {