Rollup merge of #104594 - compiler-errors:dyn-star-rcvr, r=eholk,estebank

Properly handle `Pin<&mut dyn* Trait>` receiver in codegen

This ensures we can actually await a `dyn* Future`, which seems important for async fn in dyn trait.

Also, disable `dyn*` trait upcasting. It's not exactly complete right now, and can cause strange ICEs for no reason -- nobody's using it either. I thought it was cute to implement when I did it, but I didn't think about how it interacts structurally with `CoerceUnsized` correctly.

Fixes #104794, presumably removing `dyn*` upcasting and its `CoerceUnsized` issues does the trick.

10 files changed, 137 insertions, 4 deletions

diff --git a/src/test/ui/dyn-star/dispatch-on-pin-mut.rs b/src/test/ui/dyn-star/dispatch-on-pin-mut.rs
new file mode 100644
index 00000000000..5774c8b2a67
--- /dev/null
+++ b/src/test/ui/dyn-star/dispatch-on-pin-mut.rs
@@ -0,0 +1,52 @@
+// run-pass
+// edition:2021
+// check-run-results
+
+#![feature(dyn_star)]
+//~^ WARN the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
+
+use std::future::Future;
+
+async fn foo(f: dyn* Future<Output = i32>) {
+    println!("value: {}", f.await);
+}
+
+async fn async_main() {
+    foo(Box::pin(async { 1 })).await
+}
+
+// ------------------------------------------------------------------------- //
+// Implementation Details Below...
+
+use std::pin::Pin;
+use std::task::*;
+
+pub fn noop_waker() -> Waker {
+    let raw = RawWaker::new(std::ptr::null(), &NOOP_WAKER_VTABLE);
+
+    // SAFETY: the contracts for RawWaker and RawWakerVTable are upheld
+    unsafe { Waker::from_raw(raw) }
+}
+
+const NOOP_WAKER_VTABLE: RawWakerVTable = RawWakerVTable::new(noop_clone, noop, noop, noop);
+
+unsafe fn noop_clone(_p: *const ()) -> RawWaker {
+    RawWaker::new(std::ptr::null(), &NOOP_WAKER_VTABLE)
+}
+
+unsafe fn noop(_p: *const ()) {}
+
+fn main() {
+    let mut fut = async_main();
+
+    // Poll loop, just to test the future...
+    let waker = noop_waker();
+    let ctx = &mut Context::from_waker(&waker);
+
+    loop {
+        match unsafe { Pin::new_unchecked(&mut fut).poll(ctx) } {
+            Poll::Pending => {}
+            Poll::Ready(()) => break,
+        }
+    }
+}
diff --git a/src/test/ui/dyn-star/dispatch-on-pin-mut.run.stdout b/src/test/ui/dyn-star/dispatch-on-pin-mut.run.stdout
new file mode 100644
index 00000000000..96c5ca6985f
--- /dev/null
+++ b/src/test/ui/dyn-star/dispatch-on-pin-mut.run.stdout
@@ -0,0 +1 @@
+value: 1
diff --git a/src/test/ui/dyn-star/dispatch-on-pin-mut.stderr b/src/test/ui/dyn-star/dispatch-on-pin-mut.stderr
new file mode 100644
index 00000000000..fdf74aa7efe
--- /dev/null
+++ b/src/test/ui/dyn-star/dispatch-on-pin-mut.stderr
@@ -0,0 +1,11 @@
+warning: the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/dispatch-on-pin-mut.rs:5:12
+   |
+LL | #![feature(dyn_star)]
+   |            ^^^^^^^^
+   |
+   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.rs b/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.rs
index b4ff8a22286..c12b16f1605 100644
--- a/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.rs
+++ b/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.rs
@@ -1,7 +1,8 @@
-// check-pass
+// run-pass
+// check-run-results
 
 #![feature(dyn_star)]
-#![allow(incomplete_features)]
+//~^ WARN the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
 
 trait AddOne {
     fn add1(&mut self) -> usize;
diff --git a/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.run.stdout b/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.run.stdout
new file mode 100644
index 00000000000..b4db3ed707d
--- /dev/null
+++ b/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.run.stdout
@@ -0,0 +1,2 @@
+43
+44
diff --git a/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.stderr b/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.stderr
new file mode 100644
index 00000000000..933c133831a
--- /dev/null
+++ b/src/test/ui/dyn-star/dont-unsize-coerce-dyn-star.stderr
@@ -0,0 +1,11 @@
+warning: the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/dont-unsize-coerce-dyn-star.rs:4:12
+   |
+LL | #![feature(dyn_star)]
+   |            ^^^^^^^^
+   |
+   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/dyn-star/no-unsize-coerce-dyn-trait.rs b/src/test/ui/dyn-star/no-unsize-coerce-dyn-trait.rs
new file mode 100644
index 00000000000..a4eb669e321
--- /dev/null
+++ b/src/test/ui/dyn-star/no-unsize-coerce-dyn-trait.rs
@@ -0,0 +1,13 @@
+#![feature(dyn_star, trait_upcasting)]
+//~^ WARN the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
+
+trait A: B {}
+trait B {}
+impl A for usize {}
+impl B for usize {}
+
+fn main() {
+    let x: Box<dyn* A> = Box::new(1usize as dyn* A);
+    let y: Box<dyn* B> = x;
+    //~^ ERROR mismatched types
+}
diff --git a/src/test/ui/dyn-star/no-unsize-coerce-dyn-trait.stderr b/src/test/ui/dyn-star/no-unsize-coerce-dyn-trait.stderr
new file mode 100644
index 00000000000..2fc751b3b4a
--- /dev/null
+++ b/src/test/ui/dyn-star/no-unsize-coerce-dyn-trait.stderr
@@ -0,0 +1,23 @@
+warning: the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/no-unsize-coerce-dyn-trait.rs:1:12
+   |
+LL | #![feature(dyn_star, trait_upcasting)]
+   |            ^^^^^^^^
+   |
+   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0308]: mismatched types
+  --> $DIR/no-unsize-coerce-dyn-trait.rs:11:26
+   |
+LL |     let y: Box<dyn* B> = x;
+   |            -----------   ^ expected trait `B`, found trait `A`
+   |            |
+   |            expected due to this
+   |
+   = note: expected struct `Box<dyn* B>`
+              found struct `Box<dyn* A>`
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/dyn-star/upcast.rs b/src/test/ui/dyn-star/upcast.rs
index cee76ada7df..c667ac143a3 100644
--- a/src/test/ui/dyn-star/upcast.rs
+++ b/src/test/ui/dyn-star/upcast.rs
@@ -1,7 +1,6 @@
-// run-pass
+// known-bug: #104800
 
 #![feature(dyn_star, trait_upcasting)]
-#![allow(incomplete_features)]
 
 trait Foo: Bar {
     fn hello(&self);
diff --git a/src/test/ui/dyn-star/upcast.stderr b/src/test/ui/dyn-star/upcast.stderr
new file mode 100644
index 00000000000..6a95f7754e6
--- /dev/null
+++ b/src/test/ui/dyn-star/upcast.stderr
@@ -0,0 +1,20 @@
+warning: the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/upcast.rs:3:12
+   |
+LL | #![feature(dyn_star, trait_upcasting)]
+   |            ^^^^^^^^
+   |
+   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0277]: `dyn* Foo` needs to be a pointer-sized type
+  --> $DIR/upcast.rs:30:23
+   |
+LL |     let w: dyn* Bar = w;
+   |                       ^ `dyn* Foo` needs to be a pointer-sized type
+   |
+   = help: the trait `PointerSized` is not implemented for `dyn* Foo`
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0277`.