Rollup merge of rust-lang#107769 - compiler-errors:pointer-like, r=eholk

Rename `PointerSized` to `PointerLike`

The old name was unnecessarily vague. This PR renames a nightly language feature that I added, so I don't think it needs any additional approval, though anyone can feel free to speak up if you dislike the rename.

It's still unsatisfying that we don't the user which of {size, alignment} is wrong, but this trait really is just a stepping stone for a more generalized mechanism to create `dyn*`, just meant for nightly testing, so I don't think it really deserves additional diagnostic machinery for now.

Fixes rust-lang#107696, cc `@RalfJung`
r? `@eholk`

Author: matthiaskrgr

compiler/rustc_const_eval/src/interpret/cast.rs

@@ -126,7 +126,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     let vtable = self.get_vtable_ptr(src.layout.ty, data.principal())?;
                     let vtable = Scalar::from_maybe_pointer(vtable, self);
                     let data = self.read_immediate(src)?.to_scalar();
-                    let _assert_pointer_sized = data.to_pointer(self)?;
+                    let _assert_pointer_like = data.to_pointer(self)?;
                     let val = Immediate::ScalarPair(data, vtable);
                     self.write_immediate(val, dest)?;
                 } else {

compiler/rustc_hir/src/lang_items.rs

@@ -287,7 +287,7 @@ language_item_table! {
     TryTraitBranch,          sym::branch,              branch_fn,                  Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
     TryTraitFromYeet,        sym::from_yeet,           from_yeet_fn,               Target::Fn,             GenericRequirement::None;
 
-    PointerSized,            sym::pointer_sized,       pointer_sized,              Target::Trait,          GenericRequirement::Exact(0);
+    PointerLike,             sym::pointer_like,        pointer_like,               Target::Trait,          GenericRequirement::Exact(0);
 
     Poll,                    sym::Poll,                poll,                       Target::Enum,           GenericRequirement::None;
     PollReady,               sym::Ready,               poll_ready_variant,         Target::Variant,        GenericRequirement::None;

compiler/rustc_hir_typeck/src/coercion.rs

@@ -765,7 +765,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
             self.cause.clone(),
             self.param_env,
             ty::Binder::dummy(
-                self.tcx.at(self.cause.span).mk_trait_ref(hir::LangItem::PointerSized, [a]),
+                self.tcx.at(self.cause.span).mk_trait_ref(hir::LangItem::PointerLike, [a]),
             ),
         ));
 

compiler/rustc_span/src/symbol.rs

@@ -1084,7 +1084,7 @@ symbols! {
         plugins,
         pointee_trait,
         pointer,
-        pointer_sized,
+        pointer_like,
         poll,
         position,
         post_dash_lto: "post-lto",

compiler/rustc_trait_selection/src/solve/assembly.rs

@@ -128,9 +128,9 @@ pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy + Eq {
         goal: Goal<'tcx, Self>,
     ) -> QueryResult<'tcx>;
 
-    // A type is `PointerSized` if we can compute its layout, and that layout
+    // A type is `PointerLike` if we can compute its layout, and that layout
     // matches the layout of `usize`.
-    fn consider_builtin_pointer_sized_candidate(
+    fn consider_builtin_pointer_like_candidate(
         ecx: &mut EvalCtxt<'_, 'tcx>,
         goal: Goal<'tcx, Self>,
     ) -> QueryResult<'tcx>;
@@ -312,8 +312,8 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
             || lang_items.clone_trait() == Some(trait_def_id)
         {
             G::consider_builtin_copy_clone_candidate(self, goal)
-        } else if lang_items.pointer_sized() == Some(trait_def_id) {
-            G::consider_builtin_pointer_sized_candidate(self, goal)
+        } else if lang_items.pointer_like() == Some(trait_def_id) {
+            G::consider_builtin_pointer_like_candidate(self, goal)
         } else if let Some(kind) = self.tcx().fn_trait_kind_from_def_id(trait_def_id) {
             G::consider_builtin_fn_trait_candidates(self, goal, kind)
         } else if lang_items.tuple_trait() == Some(trait_def_id) {

compiler/rustc_trait_selection/src/solve/project_goals.rs

@@ -370,11 +370,11 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
         bug!("`Copy`/`Clone` does not have an associated type: {:?}", goal);
     }
 
-    fn consider_builtin_pointer_sized_candidate(
+    fn consider_builtin_pointer_like_candidate(
         _ecx: &mut EvalCtxt<'_, 'tcx>,
         goal: Goal<'tcx, Self>,
     ) -> QueryResult<'tcx> {
-        bug!("`PointerSized` does not have an associated type: {:?}", goal);
+        bug!("`PointerLike` does not have an associated type: {:?}", goal);
     }
 
     fn consider_builtin_fn_trait_candidates(

compiler/rustc_trait_selection/src/solve/trait_goals.rs

@@ -131,7 +131,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
         )
     }
 
-    fn consider_builtin_pointer_sized_candidate(
+    fn consider_builtin_pointer_like_candidate(
         ecx: &mut EvalCtxt<'_, 'tcx>,
         goal: Goal<'tcx, Self>,
     ) -> QueryResult<'tcx> {

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

@@ -94,7 +94,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 self.assemble_candidates_for_transmutability(obligation, &mut candidates);
             } else if lang_items.tuple_trait() == Some(def_id) {
                 self.assemble_candidate_for_tuple(obligation, &mut candidates);
-            } else if lang_items.pointer_sized() == Some(def_id) {
+            } else if lang_items.pointer_like() == Some(def_id) {
                 self.assemble_candidate_for_ptr_sized(obligation, &mut candidates);
             } else {
                 if lang_items.clone_trait() == Some(def_id) {

library/core/src/marker.rs

@@ -872,13 +872,14 @@ pub trait Destruct {}
 pub trait Tuple {}
 
 /// A marker for things
-#[unstable(feature = "pointer_sized_trait", issue = "none")]
-#[lang = "pointer_sized"]
+#[unstable(feature = "pointer_like_trait", issue = "none")]
+#[cfg_attr(bootstrap, lang = "pointer_sized")]
+#[cfg_attr(not(bootstrap), lang = "pointer_like")]
 #[rustc_on_unimplemented(
-    message = "`{Self}` needs to be a pointer-sized type",
-    label = "`{Self}` needs to be a pointer-sized type"
+    message = "`{Self}` needs to have the same alignment and size as a pointer",
+    label = "`{Self}` needs to be a pointer-like type"
 )]
-pub trait PointerSized {}
+pub trait PointerLike {}
 
 /// Implementations of `Copy` for primitive types.
 ///

tests/ui/dyn-star/align.over_aligned.stderr

@@ -7,13 +7,13 @@ LL | #![feature(dyn_star)]
    = note: see issue #102425 <https://github.com/rust-lang/rust/issues/102425> for more information
    = note: `#[warn(incomplete_features)]` on by default
 
-error[E0277]: `AlignedUsize` needs to be a pointer-sized type
+error[E0277]: `AlignedUsize` needs to have the same alignment and size as a pointer
   --> $DIR/align.rs:15:13
    |
 LL |     let x = AlignedUsize(12) as dyn* Debug;
-   |             ^^^^^^^^^^^^^^^^ `AlignedUsize` needs to be a pointer-sized type
+   |             ^^^^^^^^^^^^^^^^ `AlignedUsize` needs to be a pointer-like type
    |
-   = help: the trait `PointerSized` is not implemented for `AlignedUsize`
+   = help: the trait `PointerLike` is not implemented for `AlignedUsize`
 
 error: aborting due to previous error; 1 warning emitted
 

tests/ui/dyn-star/align.rs

@@ -13,5 +13,5 @@ struct AlignedUsize(usize);
 
 fn main() {
     let x = AlignedUsize(12) as dyn* Debug;
-    //[over_aligned]~^ ERROR `AlignedUsize` needs to be a pointer-sized type
+    //[over_aligned]~^ ERROR `AlignedUsize` needs to have the same alignment and size as a pointer
 }

tests/ui/dyn-star/check-size-at-cast-polymorphic-bad.rs

@@ -9,7 +9,7 @@ fn dyn_debug(_: (dyn* Debug + '_)) {
 
 fn polymorphic<T: Debug + ?Sized>(t: &T) {
     dyn_debug(t);
-    //~^ ERROR `&T` needs to be a pointer-sized type
+    //~^ ERROR `&T` needs to have the same alignment and size as a pointer
 }
 
 fn main() {}

tests/ui/dyn-star/check-size-at-cast-polymorphic-bad.stderr

@@ -1,14 +1,14 @@
-error[E0277]: `&T` needs to be a pointer-sized type
+error[E0277]: `&T` needs to have the same alignment and size as a pointer
   --> $DIR/check-size-at-cast-polymorphic-bad.rs:11:15
    |
 LL |     dyn_debug(t);
-   |               ^ `&T` needs to be a pointer-sized type
+   |               ^ `&T` needs to be a pointer-like type
    |
-   = help: the trait `PointerSized` is not implemented for `&T`
+   = help: the trait `PointerLike` is not implemented for `&T`
 help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement
    |
-LL | fn polymorphic<T: Debug + ?Sized>(t: &T) where &T: PointerSized {
-   |                                          ++++++++++++++++++++++
+LL | fn polymorphic<T: Debug + ?Sized>(t: &T) where &T: PointerLike {
+   |                                          +++++++++++++++++++++
 
 error: aborting due to previous error
 

tests/ui/dyn-star/check-size-at-cast.rs

@@ -5,6 +5,6 @@ use std::fmt::Debug;
 
 fn main() {
     let i = [1, 2, 3, 4] as dyn* Debug;
-    //~^ ERROR `[i32; 4]` needs to be a pointer-sized type
+    //~^ ERROR `[i32; 4]` needs to have the same alignment and size as a pointer
     dbg!(i);
 }

tests/ui/dyn-star/check-size-at-cast.stderr

@@ -1,10 +1,10 @@
-error[E0277]: `[i32; 4]` needs to be a pointer-sized type
+error[E0277]: `[i32; 4]` needs to have the same alignment and size as a pointer
   --> $DIR/check-size-at-cast.rs:7:13
    |
 LL |     let i = [1, 2, 3, 4] as dyn* Debug;
-   |             ^^^^^^^^^^^^ `[i32; 4]` needs to be a pointer-sized type
+   |             ^^^^^^^^^^^^ `[i32; 4]` needs to be a pointer-like type
    |
-   = help: the trait `PointerSized` is not implemented for `[i32; 4]`
+   = help: the trait `PointerLike` is not implemented for `[i32; 4]`
 
 error: aborting due to previous error
 

tests/ui/dyn-star/upcast.stderr

@@ -7,13 +7,13 @@ LL | #![feature(dyn_star, trait_upcasting)]
    = note: see issue #102425 <https://github.com/rust-lang/rust/issues/102425> for more information
    = note: `#[warn(incomplete_features)]` on by default
 
-error[E0277]: `dyn* Foo` needs to be a pointer-sized type
+error[E0277]: `dyn* Foo` needs to have the same alignment and size as a pointer
   --> $DIR/upcast.rs:30:23
    |
 LL |     let w: dyn* Bar = w;
-   |                       ^ `dyn* Foo` needs to be a pointer-sized type
+   |                       ^ `dyn* Foo` needs to be a pointer-like type
    |
-   = help: the trait `PointerSized` is not implemented for `dyn* Foo`
+   = help: the trait `PointerLike` is not implemented for `dyn* Foo`
 
 error: aborting due to previous error; 1 warning emitted
 

tests/ui/traits/new-solver/pointer-like.rs

@@ -0,0 +1,14 @@
+// compile-flags: -Ztrait-solver=next
+
+#![feature(pointer_like_trait)]
+
+use std::marker::PointerLike;
+
+fn require_(_: impl PointerLike) {}
+
+fn main() {
+    require_(1usize);
+    require_(1u16);
+    //~^ ERROR `u16` needs to have the same alignment and size as a pointer
+    require_(&1i16);
+}

tests/ui/traits/new-solver/pointer-like.stderr

@@ -0,0 +1,24 @@
+error[E0277]: `u16` needs to have the same alignment and size as a pointer
+  --> $DIR/pointer-like.rs:11:14
+   |
+LL |     require_(1u16);
+   |     -------- ^^^^ the trait `PointerLike` is not implemented for `u16`
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = note: the trait bound `u16: PointerLike` is not satisfied
+note: required by a bound in `require_`
+  --> $DIR/pointer-like.rs:7:21
+   |
+LL | fn require_(_: impl PointerLike) {}
+   |                     ^^^^^^^^^^^ required by this bound in `require_`
+help: consider borrowing here
+   |
+LL |     require_(&1u16);
+   |              +
+LL |     require_(&mut 1u16);
+   |              ++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.