Rollup merge of #92191 - jackh726:issue-89352, r=nikomatsakis

Prefer projection candidates instead of param_env candidates for Sized predicates

Fixes #89352

Also includes some drive by logging and verbose printing changes that I found useful when debugging this, but I can remove this if needed.

This is a little hacky - but imo no more than the rest of `candidate_should_be_dropped_in_favor_of`. Importantly, in a Chalk-like world, both candidates should be completely compatible.

r? ```@nikomatsakis```

5 files changed, 40 insertions, 8 deletions

diff --git a/src/test/ui/associated-types/substs-ppaux.rs b/src/test/ui/associated-types/substs-ppaux.rs
index 66cd94d7a1b..974a1d961a0 100644
--- a/src/test/ui/associated-types/substs-ppaux.rs
+++ b/src/test/ui/associated-types/substs-ppaux.rs
@@ -25,7 +25,7 @@ fn foo<'z>() where &'z (): Sized {
     let x: () = <i8 as Foo<'static, 'static,  u32>>::bar::<'static, char>;
     //[verbose]~^ ERROR mismatched types
     //[verbose]~| expected unit type `()`
-    //[verbose]~| found fn item `fn() {<i8 as Foo<ReStatic, ReStatic>>::bar::<ReStatic, char>}`
+    //[verbose]~| found fn item `fn() {<i8 as Foo<ReStatic, ReStatic, u32>>::bar::<ReStatic, char>}`
     //[normal]~^^^^ ERROR mismatched types
     //[normal]~| expected unit type `()`
     //[normal]~| found fn item `fn() {<i8 as Foo<'static, 'static>>::bar::<'static, char>}`
diff --git a/src/test/ui/associated-types/substs-ppaux.verbose.stderr b/src/test/ui/associated-types/substs-ppaux.verbose.stderr
index b831f3b7a76..cf480223da2 100644
--- a/src/test/ui/associated-types/substs-ppaux.verbose.stderr
+++ b/src/test/ui/associated-types/substs-ppaux.verbose.stderr
@@ -20,7 +20,7 @@ error[E0308]: mismatched types
   --> $DIR/substs-ppaux.rs:25:17
    |
 LL |     fn bar<'a, T>() where T: 'a {}
-   |     --------------------------- fn() {<i8 as Foo<ReStatic, ReStatic>>::bar::<ReStatic, char>} defined here
+   |     --------------------------- fn() {<i8 as Foo<ReStatic, ReStatic, u32>>::bar::<ReStatic, char>} defined here
 ...
 LL |     let x: () = <i8 as Foo<'static, 'static,  u32>>::bar::<'static, char>;
    |            --   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found fn item
@@ -28,7 +28,7 @@ LL |     let x: () = <i8 as Foo<'static, 'static,  u32>>::bar::<'static, char>;
    |            expected due to this
    |
    = note: expected unit type `()`
-                found fn item `fn() {<i8 as Foo<ReStatic, ReStatic>>::bar::<ReStatic, char>}`
+                found fn item `fn() {<i8 as Foo<ReStatic, ReStatic, u32>>::bar::<ReStatic, char>}`
 help: use parentheses to call this function
    |
 LL |     let x: () = <i8 as Foo<'static, 'static,  u32>>::bar::<'static, char>();
diff --git a/src/test/ui/generic-associated-types/issue-89352.rs b/src/test/ui/generic-associated-types/issue-89352.rs
new file mode 100644
index 00000000000..d9c656d5f58
--- /dev/null
+++ b/src/test/ui/generic-associated-types/issue-89352.rs
@@ -0,0 +1,32 @@
+// check-pass
+
+#![feature(generic_associated_types)]
+
+use std::marker::PhantomData;
+
+pub trait GenAssoc<T> {
+    type Iter<'at>;
+    fn iter(&self) -> Self::Iter<'_>;
+    fn reborrow<'longt: 'shortt, 'shortt>(iter: Self::Iter<'longt>) -> Self::Iter<'shortt>;
+}
+
+pub struct Wrapper<'a, T: 'a, A: GenAssoc<T>> {
+    a: A::Iter<'a>,
+    _p: PhantomData<T>,
+}
+
+impl<'ai, T: 'ai, A: GenAssoc<T>> GenAssoc<T> for Wrapper<'ai, T, A>
+where
+    A::Iter<'ai>: Clone,
+{
+    type Iter<'b> = ();
+    fn iter<'s>(&'s self) -> Self::Iter<'s> {
+        let a = A::reborrow::<'ai, 's>(self.a.clone());
+    }
+
+    fn reborrow<'long: 'short, 'short>(iter: Self::Iter<'long>) -> Self::Iter<'short> {
+        ()
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/nll/ty-outlives/projection-no-regions-closure.stderr b/src/test/ui/nll/ty-outlives/projection-no-regions-closure.stderr
index 983d6a06afa..459198eec5a 100644
--- a/src/test/ui/nll/ty-outlives/projection-no-regions-closure.stderr
+++ b/src/test/ui/nll/ty-outlives/projection-no-regions-closure.stderr
@@ -6,7 +6,7 @@ LL |     with_signature(x, |mut y| Box::new(y.next()))
    |
    = note: defining type: no_region::<'_#1r, T>::{closure#0} with closure substs [
                i32,
-               extern "rust-call" fn((std::boxed::Box<T>,)) -> std::boxed::Box<(dyn Anything + '_#2r)>,
+               extern "rust-call" fn((std::boxed::Box<T, std::alloc::Global>,)) -> std::boxed::Box<(dyn Anything + '_#2r), std::alloc::Global>,
                (),
            ]
    = note: number of external vids: 3
@@ -42,7 +42,7 @@ LL |     with_signature(x, |mut y| Box::new(y.next()))
    |
    = note: defining type: correct_region::<'_#1r, T>::{closure#0} with closure substs [
                i32,
-               extern "rust-call" fn((std::boxed::Box<T>,)) -> std::boxed::Box<(dyn Anything + '_#2r)>,
+               extern "rust-call" fn((std::boxed::Box<T, std::alloc::Global>,)) -> std::boxed::Box<(dyn Anything + '_#2r), std::alloc::Global>,
                (),
            ]
    = note: number of external vids: 3
@@ -69,7 +69,7 @@ LL |     with_signature(x, |mut y| Box::new(y.next()))
    |
    = note: defining type: wrong_region::<'_#1r, '_#2r, T>::{closure#0} with closure substs [
                i32,
-               extern "rust-call" fn((std::boxed::Box<T>,)) -> std::boxed::Box<(dyn Anything + '_#3r)>,
+               extern "rust-call" fn((std::boxed::Box<T, std::alloc::Global>,)) -> std::boxed::Box<(dyn Anything + '_#3r), std::alloc::Global>,
                (),
            ]
    = note: number of external vids: 4
@@ -105,7 +105,7 @@ LL |     with_signature(x, |mut y| Box::new(y.next()))
    |
    = note: defining type: outlives_region::<'_#1r, '_#2r, T>::{closure#0} with closure substs [
                i32,
-               extern "rust-call" fn((std::boxed::Box<T>,)) -> std::boxed::Box<(dyn Anything + '_#3r)>,
+               extern "rust-call" fn((std::boxed::Box<T, std::alloc::Global>,)) -> std::boxed::Box<(dyn Anything + '_#3r), std::alloc::Global>,
                (),
            ]
    = note: number of external vids: 4
diff --git a/src/test/ui/nll/ty-outlives/ty-param-closure-outlives-from-return-type.stderr b/src/test/ui/nll/ty-outlives/ty-param-closure-outlives-from-return-type.stderr
index 88d73e7a729..6e8b3021d33 100644
--- a/src/test/ui/nll/ty-outlives/ty-param-closure-outlives-from-return-type.stderr
+++ b/src/test/ui/nll/ty-outlives/ty-param-closure-outlives-from-return-type.stderr
@@ -6,7 +6,7 @@ LL |     with_signature(x, |y| y)
    |
    = note: defining type: no_region::<'_#1r, T>::{closure#0} with closure substs [
                i32,
-               extern "rust-call" fn((std::boxed::Box<T>,)) -> std::boxed::Box<(dyn std::fmt::Debug + '_#2r)>,
+               extern "rust-call" fn((std::boxed::Box<T, std::alloc::Global>,)) -> std::boxed::Box<(dyn std::fmt::Debug + '_#2r), std::alloc::Global>,
                (),
            ]
    = note: number of external vids: 3