Rollup merge of #127681 - dingxiangfei2009:smart-ptr-bounds, r=compiler-errors

derive(SmartPointer): rewrite bounds in where and generic bounds

Fix #127647

Due to the `Unsize` bounds, we need to commute the bounds on the pointee type to the new self type.

cc ```@Darksonn```

3 files changed, 144 insertions, 0 deletions

diff --git a/tests/ui/deriving/deriving-smart-pointer-expanded.rs b/tests/ui/deriving/deriving-smart-pointer-expanded.rs
new file mode 100644
index 00000000000..b78258c2529
--- /dev/null
+++ b/tests/ui/deriving/deriving-smart-pointer-expanded.rs
@@ -0,0 +1,22 @@
+//@ check-pass
+//@ compile-flags: -Zunpretty=expanded
+#![feature(derive_smart_pointer)]
+use std::marker::SmartPointer;
+
+pub trait MyTrait<T: ?Sized> {}
+
+#[derive(SmartPointer)]
+#[repr(transparent)]
+struct MyPointer<'a, #[pointee] T: ?Sized> {
+    ptr: &'a T,
+}
+
+#[derive(core::marker::SmartPointer)]
+#[repr(transparent)]
+pub struct MyPointer2<'a, Y, Z: MyTrait<T>, #[pointee] T: ?Sized + MyTrait<T>, X: MyTrait<T> = ()>
+where
+    Y: MyTrait<T>,
+{
+    data: &'a mut T,
+    x: core::marker::PhantomData<X>,
+}
diff --git a/tests/ui/deriving/deriving-smart-pointer-expanded.stdout b/tests/ui/deriving/deriving-smart-pointer-expanded.stdout
new file mode 100644
index 00000000000..3c7e7198180
--- /dev/null
+++ b/tests/ui/deriving/deriving-smart-pointer-expanded.stdout
@@ -0,0 +1,44 @@
+#![feature(prelude_import)]
+#![no_std]
+//@ check-pass
+//@ compile-flags: -Zunpretty=expanded
+#![feature(derive_smart_pointer)]
+#[prelude_import]
+use ::std::prelude::rust_2015::*;
+#[macro_use]
+extern crate std;
+use std::marker::SmartPointer;
+
+pub trait MyTrait<T: ?Sized> {}
+
+#[repr(transparent)]
+struct MyPointer<'a, #[pointee] T: ?Sized> {
+    ptr: &'a T,
+}
+#[automatically_derived]
+impl<'a, T: ?Sized + ::core::marker::Unsize<__S>, __S: ?Sized>
+    ::core::ops::DispatchFromDyn<MyPointer<'a, __S>> for MyPointer<'a, T> {
+}
+#[automatically_derived]
+impl<'a, T: ?Sized + ::core::marker::Unsize<__S>, __S: ?Sized>
+    ::core::ops::CoerceUnsized<MyPointer<'a, __S>> for MyPointer<'a, T> {
+}
+
+#[repr(transparent)]
+pub struct MyPointer2<'a, Y, Z: MyTrait<T>, #[pointee] T: ?Sized + MyTrait<T>,
+    X: MyTrait<T> = ()> where Y: MyTrait<T> {
+    data: &'a mut T,
+    x: core::marker::PhantomData<X>,
+}
+#[automatically_derived]
+impl<'a, Y, Z: MyTrait<T> + MyTrait<__S>, T: ?Sized + MyTrait<T> +
+    ::core::marker::Unsize<__S>, __S: ?Sized + MyTrait<__S>, X: MyTrait<T> +
+    MyTrait<__S>> ::core::ops::DispatchFromDyn<MyPointer2<'a, Y, Z, __S, X>>
+    for MyPointer2<'a, Y, Z, T, X> where Y: MyTrait<T>, Y: MyTrait<__S> {
+}
+#[automatically_derived]
+impl<'a, Y, Z: MyTrait<T> + MyTrait<__S>, T: ?Sized + MyTrait<T> +
+    ::core::marker::Unsize<__S>, __S: ?Sized + MyTrait<__S>, X: MyTrait<T> +
+    MyTrait<__S>> ::core::ops::CoerceUnsized<MyPointer2<'a, Y, Z, __S, X>> for
+    MyPointer2<'a, Y, Z, T, X> where Y: MyTrait<T>, Y: MyTrait<__S> {
+}
diff --git a/tests/ui/deriving/smart-pointer-bounds-issue-127647.rs b/tests/ui/deriving/smart-pointer-bounds-issue-127647.rs
new file mode 100644
index 00000000000..4cae1b32896
--- /dev/null
+++ b/tests/ui/deriving/smart-pointer-bounds-issue-127647.rs
@@ -0,0 +1,78 @@
+//@ check-pass
+
+#![feature(derive_smart_pointer)]
+
+#[derive(core::marker::SmartPointer)]
+#[repr(transparent)]
+pub struct Ptr<'a, #[pointee] T: OnDrop + ?Sized, X> {
+    data: &'a mut T,
+    x: core::marker::PhantomData<X>,
+}
+
+pub trait OnDrop {
+    fn on_drop(&mut self);
+}
+
+#[derive(core::marker::SmartPointer)]
+#[repr(transparent)]
+pub struct Ptr2<'a, #[pointee] T: ?Sized, X>
+where
+    T: OnDrop,
+{
+    data: &'a mut T,
+    x: core::marker::PhantomData<X>,
+}
+
+pub trait MyTrait<T: ?Sized> {}
+
+#[derive(core::marker::SmartPointer)]
+#[repr(transparent)]
+pub struct Ptr3<'a, #[pointee] T: ?Sized, X>
+where
+    T: MyTrait<T>,
+{
+    data: &'a mut T,
+    x: core::marker::PhantomData<X>,
+}
+
+#[derive(core::marker::SmartPointer)]
+#[repr(transparent)]
+pub struct Ptr4<'a, #[pointee] T: MyTrait<T> + ?Sized, X> {
+    data: &'a mut T,
+    x: core::marker::PhantomData<X>,
+}
+
+#[derive(core::marker::SmartPointer)]
+#[repr(transparent)]
+pub struct Ptr5<'a, #[pointee] T: ?Sized, X>
+where
+    Ptr5Companion<T>: MyTrait<T>,
+    Ptr5Companion2: MyTrait<T>,
+{
+    data: &'a mut T,
+    x: core::marker::PhantomData<X>,
+}
+
+pub struct Ptr5Companion<T: ?Sized>(core::marker::PhantomData<T>);
+pub struct Ptr5Companion2;
+
+#[derive(core::marker::SmartPointer)]
+#[repr(transparent)]
+pub struct Ptr6<'a, #[pointee] T: ?Sized, X: MyTrait<T> = (), const PARAM: usize = 0> {
+    data: &'a mut T,
+    x: core::marker::PhantomData<X>,
+}
+
+// a reduced example from https://lore.kernel.org/all/20240402-linked-list-v1-1-b1c59ba7ae3b@google.com/
+#[repr(transparent)]
+#[derive(core::marker::SmartPointer)]
+pub struct ListArc<#[pointee] T, const ID: u64 = 0>
+where
+    T: ListArcSafe<ID> + ?Sized,
+{
+    arc: *const T,
+}
+
+pub trait ListArcSafe<const ID: u64> {}
+
+fn main() {}