Auto merge of #96515 - lcnr:user-types-in-pat, r=nikomatsakis

correctly deal with user type ascriptions in pat

supersedes #93856

`thir::PatKind::AscribeUserType` previously resulted in `CanonicalUserTypeAnnotations` where the inferred type already had a subtyping relation according to `variance` to the `user_ty`.

The bug can pretty much be summarized as follows:

- during mir building
  - `user_ty -> inferred_ty`: considers variance
  - `StatementKind::AscribeUserType`: `inferred_ty` is the type of the place, so no variance needed
- during mir borrowck
  - `user_ty -> inferred_ty`: does not consider variance
  - `StatementKind::AscribeUserType`: applies variance

This mostly worked fine. The lifetimes in `inferred_ty` were only bound by its relation to `user_ty` and to the `place` of `StatementKind::AscribeUserType`, so it doesn't matter where exactly the subtyping happens.

It does however matter when having higher ranked subtying. At this point the place where the subtyping happens is forced, causing this mismatch between building and borrowck to result in unintended errors.

cc #96514 which is pretty much the same issue

r? `@nikomatsakis`

15 files changed, 239 insertions, 84 deletions

diff --git a/src/test/mir-opt/address_of.address_of_reborrow.SimplifyCfg-initial.after.mir b/src/test/mir-opt/address_of.address_of_reborrow.SimplifyCfg-initial.after.mir
index 9fa478f8a82..ee8e2178148 100644
--- a/src/test/mir-opt/address_of.address_of_reborrow.SimplifyCfg-initial.after.mir
+++ b/src/test/mir-opt/address_of.address_of_reborrow.SimplifyCfg-initial.after.mir
@@ -1,36 +1,36 @@
 // MIR for `address_of_reborrow` after SimplifyCfg-initial
 
 | User Type Annotations
-| 0: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) } at $DIR/address-of.rs:7:5: 7:18
-| 1: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) } at $DIR/address-of.rs:9:5: 9:25
-| 2: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) } at $DIR/address-of.rs:13:12: 13:20
-| 3: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) } at $DIR/address-of.rs:13:12: 13:20
-| 4: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32; 10]) } at $DIR/address-of.rs:14:12: 14:28
-| 5: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32; 10]) } at $DIR/address-of.rs:14:12: 14:28
-| 6: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) } at $DIR/address-of.rs:15:12: 15:27
-| 7: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) } at $DIR/address-of.rs:15:12: 15:27
-| 8: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32]) } at $DIR/address-of.rs:16:12: 16:24
-| 9: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32]) } at $DIR/address-of.rs:16:12: 16:24
-| 10: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) } at $DIR/address-of.rs:18:5: 18:18
-| 11: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) } at $DIR/address-of.rs:20:5: 20:25
-| 12: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) } at $DIR/address-of.rs:23:12: 23:20
-| 13: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) } at $DIR/address-of.rs:23:12: 23:20
-| 14: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32; 10]) } at $DIR/address-of.rs:24:12: 24:28
-| 15: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32; 10]) } at $DIR/address-of.rs:24:12: 24:28
-| 16: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) } at $DIR/address-of.rs:25:12: 25:27
-| 17: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) } at $DIR/address-of.rs:25:12: 25:27
-| 18: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32]) } at $DIR/address-of.rs:26:12: 26:24
-| 19: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32]) } at $DIR/address-of.rs:26:12: 26:24
-| 20: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*mut ^0) } at $DIR/address-of.rs:28:5: 28:16
-| 21: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*mut dyn std::marker::Send) } at $DIR/address-of.rs:30:5: 30:23
-| 22: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*mut ^0) } at $DIR/address-of.rs:33:12: 33:18
-| 23: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*mut ^0) } at $DIR/address-of.rs:33:12: 33:18
-| 24: Canonical { max_universe: U0, variables: [], value: Ty(*mut [i32; 10]) } at $DIR/address-of.rs:34:12: 34:26
-| 25: Canonical { max_universe: U0, variables: [], value: Ty(*mut [i32; 10]) } at $DIR/address-of.rs:34:12: 34:26
-| 26: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*mut dyn std::marker::Send) } at $DIR/address-of.rs:35:12: 35:25
-| 27: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*mut dyn std::marker::Send) } at $DIR/address-of.rs:35:12: 35:25
-| 28: Canonical { max_universe: U0, variables: [], value: Ty(*mut [i32]) } at $DIR/address-of.rs:36:12: 36:22
-| 29: Canonical { max_universe: U0, variables: [], value: Ty(*mut [i32]) } at $DIR/address-of.rs:36:12: 36:22
+| 0: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) }, span: $DIR/address-of.rs:7:5: 7:18, inferred_ty: *const [i32; 10]
+| 1: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) }, span: $DIR/address-of.rs:9:5: 9:25, inferred_ty: *const dyn std::marker::Send
+| 2: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) }, span: $DIR/address-of.rs:13:12: 13:20, inferred_ty: *const [i32; 10]
+| 3: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) }, span: $DIR/address-of.rs:13:12: 13:20, inferred_ty: *const [i32; 10]
+| 4: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32; 10]) }, span: $DIR/address-of.rs:14:12: 14:28, inferred_ty: *const [i32; 10]
+| 5: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32; 10]) }, span: $DIR/address-of.rs:14:12: 14:28, inferred_ty: *const [i32; 10]
+| 6: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) }, span: $DIR/address-of.rs:15:12: 15:27, inferred_ty: *const dyn std::marker::Send
+| 7: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) }, span: $DIR/address-of.rs:15:12: 15:27, inferred_ty: *const dyn std::marker::Send
+| 8: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32]) }, span: $DIR/address-of.rs:16:12: 16:24, inferred_ty: *const [i32]
+| 9: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32]) }, span: $DIR/address-of.rs:16:12: 16:24, inferred_ty: *const [i32]
+| 10: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) }, span: $DIR/address-of.rs:18:5: 18:18, inferred_ty: *const [i32; 10]
+| 11: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) }, span: $DIR/address-of.rs:20:5: 20:25, inferred_ty: *const dyn std::marker::Send
+| 12: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) }, span: $DIR/address-of.rs:23:12: 23:20, inferred_ty: *const [i32; 10]
+| 13: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*const ^0) }, span: $DIR/address-of.rs:23:12: 23:20, inferred_ty: *const [i32; 10]
+| 14: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32; 10]) }, span: $DIR/address-of.rs:24:12: 24:28, inferred_ty: *const [i32; 10]
+| 15: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32; 10]) }, span: $DIR/address-of.rs:24:12: 24:28, inferred_ty: *const [i32; 10]
+| 16: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) }, span: $DIR/address-of.rs:25:12: 25:27, inferred_ty: *const dyn std::marker::Send
+| 17: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*const dyn std::marker::Send) }, span: $DIR/address-of.rs:25:12: 25:27, inferred_ty: *const dyn std::marker::Send
+| 18: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32]) }, span: $DIR/address-of.rs:26:12: 26:24, inferred_ty: *const [i32]
+| 19: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*const [i32]) }, span: $DIR/address-of.rs:26:12: 26:24, inferred_ty: *const [i32]
+| 20: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*mut ^0) }, span: $DIR/address-of.rs:28:5: 28:16, inferred_ty: *mut [i32; 10]
+| 21: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*mut dyn std::marker::Send) }, span: $DIR/address-of.rs:30:5: 30:23, inferred_ty: *mut dyn std::marker::Send
+| 22: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*mut ^0) }, span: $DIR/address-of.rs:33:12: 33:18, inferred_ty: *mut [i32; 10]
+| 23: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }], value: Ty(*mut ^0) }, span: $DIR/address-of.rs:33:12: 33:18, inferred_ty: *mut [i32; 10]
+| 24: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*mut [i32; 10]) }, span: $DIR/address-of.rs:34:12: 34:26, inferred_ty: *mut [i32; 10]
+| 25: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*mut [i32; 10]) }, span: $DIR/address-of.rs:34:12: 34:26, inferred_ty: *mut [i32; 10]
+| 26: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*mut dyn std::marker::Send) }, span: $DIR/address-of.rs:35:12: 35:25, inferred_ty: *mut dyn std::marker::Send
+| 27: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }], value: Ty(*mut dyn std::marker::Send) }, span: $DIR/address-of.rs:35:12: 35:25, inferred_ty: *mut dyn std::marker::Send
+| 28: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*mut [i32]) }, span: $DIR/address-of.rs:36:12: 36:22, inferred_ty: *mut [i32]
+| 29: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*mut [i32]) }, span: $DIR/address-of.rs:36:12: 36:22, inferred_ty: *mut [i32]
 |
 fn address_of_reborrow() -> () {
     let mut _0: ();                      // return place in scope 0 at $DIR/address-of.rs:3:26: 3:26
diff --git a/src/test/mir-opt/basic_assignment.main.SimplifyCfg-initial.after.mir b/src/test/mir-opt/basic_assignment.main.SimplifyCfg-initial.after.mir
index e751b825c05..a63a94b2ab5 100644
--- a/src/test/mir-opt/basic_assignment.main.SimplifyCfg-initial.after.mir
+++ b/src/test/mir-opt/basic_assignment.main.SimplifyCfg-initial.after.mir
@@ -1,8 +1,8 @@
 // MIR for `main` after SimplifyCfg-initial
 
 | User Type Annotations
-| 0: Canonical { max_universe: U0, variables: [], value: Ty(std::option::Option<std::boxed::Box<u32>>) } at $DIR/basic_assignment.rs:18:17: 18:33
-| 1: Canonical { max_universe: U0, variables: [], value: Ty(std::option::Option<std::boxed::Box<u32>>) } at $DIR/basic_assignment.rs:18:17: 18:33
+| 0: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(std::option::Option<std::boxed::Box<u32>>) }, span: $DIR/basic_assignment.rs:18:17: 18:33, inferred_ty: std::option::Option<std::boxed::Box<u32>>
+| 1: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(std::option::Option<std::boxed::Box<u32>>) }, span: $DIR/basic_assignment.rs:18:17: 18:33, inferred_ty: std::option::Option<std::boxed::Box<u32>>
 |
 fn main() -> () {
     let mut _0: ();                      // return place in scope 0 at $DIR/basic_assignment.rs:10:11: 10:11
diff --git a/src/test/mir-opt/issue_72181_1.main.mir_map.0.mir b/src/test/mir-opt/issue_72181_1.main.mir_map.0.mir
index 4aff4445158..7e966b21bed 100644
--- a/src/test/mir-opt/issue_72181_1.main.mir_map.0.mir
+++ b/src/test/mir-opt/issue_72181_1.main.mir_map.0.mir
@@ -1,8 +1,8 @@
 // MIR for `main` 0 mir_map
 
 | User Type Annotations
-| 0: Canonical { max_universe: U0, variables: [], value: Ty(Void) } at $DIR/issue-72181-1.rs:16:12: 16:16
-| 1: Canonical { max_universe: U0, variables: [], value: Ty(Void) } at $DIR/issue-72181-1.rs:16:12: 16:16
+| 0: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(Void) }, span: $DIR/issue-72181-1.rs:16:12: 16:16, inferred_ty: Void
+| 1: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(Void) }, span: $DIR/issue-72181-1.rs:16:12: 16:16, inferred_ty: Void
 |
 fn main() -> () {
     let mut _0: ();                      // return place in scope 0 at $DIR/issue-72181-1.rs:15:11: 15:11
diff --git a/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir b/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir
index 945290b6a82..5bf8655fcec 100644
--- a/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir
+++ b/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir
@@ -1,10 +1,10 @@
 // MIR for `main` 0 mir_map
 
 | User Type Annotations
-| 0: Canonical { max_universe: U0, variables: [], value: Ty(*mut Test) } at $DIR/receiver-ptr-mutability.rs:14:14: 14:23
-| 1: Canonical { max_universe: U0, variables: [], value: Ty(*mut Test) } at $DIR/receiver-ptr-mutability.rs:14:14: 14:23
-| 2: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }], value: Ty(&&&&*mut Test) } at $DIR/receiver-ptr-mutability.rs:18:18: 18:31
-| 3: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }], value: Ty(&&&&*mut Test) } at $DIR/receiver-ptr-mutability.rs:18:18: 18:31
+| 0: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*mut Test) }, span: $DIR/receiver-ptr-mutability.rs:14:14: 14:23, inferred_ty: *mut Test
+| 1: user_ty: Canonical { max_universe: U0, variables: [], value: Ty(*mut Test) }, span: $DIR/receiver-ptr-mutability.rs:14:14: 14:23, inferred_ty: *mut Test
+| 2: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }], value: Ty(&&&&*mut Test) }, span: $DIR/receiver-ptr-mutability.rs:18:18: 18:31, inferred_ty: &&&&*mut Test
+| 3: user_ty: Canonical { max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }], value: Ty(&&&&*mut Test) }, span: $DIR/receiver-ptr-mutability.rs:18:18: 18:31, inferred_ty: &&&&*mut Test
 |
 fn main() -> () {
     let mut _0: ();                      // return place in scope 0 at $DIR/receiver-ptr-mutability.rs:13:11: 13:11
diff --git a/src/test/ui/hr-subtype/placeholder-pattern-fail.nll.stderr b/src/test/ui/hr-subtype/placeholder-pattern-fail.nll.stderr
new file mode 100644
index 00000000000..1836249efdb
--- /dev/null
+++ b/src/test/ui/hr-subtype/placeholder-pattern-fail.nll.stderr
@@ -0,0 +1,37 @@
+error[E0308]: mismatched types
+  --> $DIR/placeholder-pattern-fail.rs:9:12
+   |
+LL |     let _: for<'a, 'b> fn(Inv<'a>, Inv<'b>) = sub;
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ one type is more general than the other
+   |
+   = note: expected fn pointer `for<'a, 'b> fn(Inv<'a>, Inv<'b>)`
+              found fn pointer `for<'a> fn(Inv<'a>, Inv<'a>)`
+
+error[E0308]: mismatched types
+  --> $DIR/placeholder-pattern-fail.rs:9:12
+   |
+LL |     let _: for<'a, 'b> fn(Inv<'a>, Inv<'b>) = sub;
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ one type is more general than the other
+   |
+   = note: expected fn pointer `for<'a, 'b> fn(Inv<'a>, Inv<'b>)`
+              found fn pointer `for<'a> fn(Inv<'a>, Inv<'a>)`
+
+error: lifetime may not live long enough
+  --> $DIR/placeholder-pattern-fail.rs:14:13
+   |
+LL | fn simple1<'c>(x: (&'c i32,)) {
+   |            -- lifetime `'c` defined here
+LL |     let _x: (&'static i32,) = x;
+   |             ^^^^^^^^^^^^^^^ type annotation requires that `'c` must outlive `'static`
+
+error: lifetime may not live long enough
+  --> $DIR/placeholder-pattern-fail.rs:19:12
+   |
+LL | fn simple2<'c>(x: (&'c i32,)) {
+   |            -- lifetime `'c` defined here
+LL |     let _: (&'static i32,) = x;
+   |            ^^^^^^^^^^^^^^^ type annotation requires that `'c` must outlive `'static`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/hr-subtype/placeholder-pattern-fail.rs b/src/test/ui/hr-subtype/placeholder-pattern-fail.rs
new file mode 100644
index 00000000000..3b5b075cb58
--- /dev/null
+++ b/src/test/ui/hr-subtype/placeholder-pattern-fail.rs
@@ -0,0 +1,27 @@
+// Check that incorrect higher ranked subtyping
+// causes an error.
+struct Inv<'a>(fn(&'a ()) -> &'a ());
+fn hr_subtype<'c>(f: for<'a, 'b> fn(Inv<'a>, Inv<'a>)) {
+    // ok
+    let _: for<'a> fn(Inv<'a>, Inv<'a>) = f;
+    let sub: for<'a> fn(Inv<'a>, Inv<'a>) = f;
+    // no
+    let _: for<'a, 'b> fn(Inv<'a>, Inv<'b>) = sub;
+    //~^ ERROR mismatched types
+}
+
+fn simple1<'c>(x: (&'c i32,)) {
+    let _x: (&'static i32,) = x;
+    //~^ ERROR mismatched types
+}
+
+fn simple2<'c>(x: (&'c i32,)) {
+    let _: (&'static i32,) = x;
+    //~^ ERROR mismatched types
+}
+
+fn main() {
+    hr_subtype(|_, _| {});
+    simple1((&3,));
+    simple2((&3,));
+}
diff --git a/src/test/ui/hr-subtype/placeholder-pattern-fail.stderr b/src/test/ui/hr-subtype/placeholder-pattern-fail.stderr
new file mode 100644
index 00000000000..7bd5308052b
--- /dev/null
+++ b/src/test/ui/hr-subtype/placeholder-pattern-fail.stderr
@@ -0,0 +1,42 @@
+error[E0308]: mismatched types
+  --> $DIR/placeholder-pattern-fail.rs:9:47
+   |
+LL |     let _: for<'a, 'b> fn(Inv<'a>, Inv<'b>) = sub;
+   |                                               ^^^ one type is more general than the other
+   |
+   = note: expected fn pointer `for<'a, 'b> fn(Inv<'a>, Inv<'b>)`
+              found fn pointer `for<'a> fn(Inv<'a>, Inv<'a>)`
+
+error[E0308]: mismatched types
+  --> $DIR/placeholder-pattern-fail.rs:14:31
+   |
+LL |     let _x: (&'static i32,) = x;
+   |                               ^ lifetime mismatch
+   |
+   = note: expected tuple `(&'static i32,)`
+              found tuple `(&'c i32,)`
+note: the lifetime `'c` as defined here...
+  --> $DIR/placeholder-pattern-fail.rs:13:12
+   |
+LL | fn simple1<'c>(x: (&'c i32,)) {
+   |            ^^
+   = note: ...does not necessarily outlive the static lifetime
+
+error[E0308]: mismatched types
+  --> $DIR/placeholder-pattern-fail.rs:19:30
+   |
+LL |     let _: (&'static i32,) = x;
+   |                              ^ lifetime mismatch
+   |
+   = note: expected tuple `(&'static i32,)`
+              found tuple `(&'c i32,)`
+note: the lifetime `'c` as defined here...
+  --> $DIR/placeholder-pattern-fail.rs:18:12
+   |
+LL | fn simple2<'c>(x: (&'c i32,)) {
+   |            ^^
+   = note: ...does not necessarily outlive the static lifetime
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/hr-subtype/placeholder-pattern.rs b/src/test/ui/hr-subtype/placeholder-pattern.rs
new file mode 100644
index 00000000000..061e66e54d2
--- /dev/null
+++ b/src/test/ui/hr-subtype/placeholder-pattern.rs
@@ -0,0 +1,18 @@
+// check-pass
+// Check that higher ranked subtyping correctly works when using
+// placeholder patterns.
+fn hr_subtype<'c>(f: for<'a, 'b> fn(&'a (), &'b ())) {
+    let _: for<'a> fn(&'a (), &'a ()) = f;
+    let _: for<'a, 'b> fn(&'a (), &'b ()) = f;
+    let _: for<'a> fn(&'a (), &'c ()) = f;
+    let _: fn(&'c (), &'c ()) = f;
+}
+
+fn simple<'c>(x: (&'static i32,)) {
+    let _: (&'c i32,) = x;
+}
+
+fn main() {
+    hr_subtype(|_, _| {});
+    simple((&3,));
+}
diff --git a/src/test/ui/lifetimes/re-empty-in-error.nll.stderr b/src/test/ui/lifetimes/re-empty-in-error.nll.stderr
new file mode 100644
index 00000000000..9becdab9186
--- /dev/null
+++ b/src/test/ui/lifetimes/re-empty-in-error.nll.stderr
@@ -0,0 +1,10 @@
+error: higher-ranked lifetime error
+  --> $DIR/re-empty-in-error.rs:8:5
+   |
+LL |     foo(&10);
+   |     ^^^^^^^^
+   |
+   = note: could not prove for<'b, 'r> &'b (): 'r
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/lifetimes/re-empty-in-error.rs b/src/test/ui/lifetimes/re-empty-in-error.rs
new file mode 100644
index 00000000000..41c3718592d
--- /dev/null
+++ b/src/test/ui/lifetimes/re-empty-in-error.rs
@@ -0,0 +1,10 @@
+// We didn't have a single test mentioning
+// `ReEmpty` and this test changes that.
+fn foo<'a>(_a: &'a u32) where for<'b> &'b (): 'a {
+    //~^ NOTE type must outlive the empty lifetime as required by this binding
+}
+
+fn main() {
+    foo(&10);
+    //~^ ERROR the type `&'b ()` does not fulfill the required lifetime
+}
diff --git a/src/test/ui/lifetimes/re-empty-in-error.stderr b/src/test/ui/lifetimes/re-empty-in-error.stderr
new file mode 100644
index 00000000000..227e3ca6139
--- /dev/null
+++ b/src/test/ui/lifetimes/re-empty-in-error.stderr
@@ -0,0 +1,15 @@
+error[E0477]: the type `&'b ()` does not fulfill the required lifetime
+  --> $DIR/re-empty-in-error.rs:8:5
+   |
+LL |     foo(&10);
+   |     ^^^
+   |
+note: type must outlive the empty lifetime as required by this binding
+  --> $DIR/re-empty-in-error.rs:3:47
+   |
+LL | fn foo<'a>(_a: &'a u32) where for<'b> &'b (): 'a {
+   |                                               ^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0477`.
diff --git a/src/test/ui/nll/issue-57280-1-flipped.rs b/src/test/ui/nll/issue-57280-1-flipped.rs
new file mode 100644
index 00000000000..ad4b8dcfde4
--- /dev/null
+++ b/src/test/ui/nll/issue-57280-1-flipped.rs
@@ -0,0 +1,23 @@
+// This test should compile, as the lifetimes
+// in matches don't really matter.
+//
+// We currently use contravariance when checking the
+// type of match arms.
+
+trait Foo<'a> {
+    const C: &'a u32;
+}
+
+impl<'a, T> Foo<'a> for T {
+    const C: &'a u32 = &22;
+}
+
+fn foo<'a>(x: &'static u32) {
+    match x {
+        <() as Foo<'a>>::C => { }
+        //~^ ERROR lifetime may not live long enough
+        &_ => { }
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/nll/issue-57280-1-flipped.stderr b/src/test/ui/nll/issue-57280-1-flipped.stderr
new file mode 100644
index 00000000000..7a2135a2ade
--- /dev/null
+++ b/src/test/ui/nll/issue-57280-1-flipped.stderr
@@ -0,0 +1,11 @@
+error: lifetime may not live long enough
+  --> $DIR/issue-57280-1-flipped.rs:17:9
+   |
+LL | fn foo<'a>(x: &'static u32) {
+   |        -- lifetime `'a` defined here
+LL |     match x {
+LL |         <() as Foo<'a>>::C => { }
+   |         ^^^^^^^^^^^^^^^^^^ type annotation requires that `'a` must outlive `'static`
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.rs b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.rs
index 9ad7cad39d0..811832848d9 100644
--- a/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.rs
+++ b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.rs
@@ -1,24 +1,8 @@
-// known-bug
-// failure-status: 101
-// compile-flags: --edition=2021 --crate-type=lib
-// rustc-env:RUST_BACKTRACE=0
-
-// normalize-stderr-test "thread 'rustc' panicked.*" -> "thread 'rustc' panicked"
-// normalize-stderr-test "note:.*RUST_BACKTRACE=1.*\n" -> ""
-// normalize-stderr-test "\nerror: internal compiler error.*\n\n" -> ""
-// normalize-stderr-test "note:.*unexpectedly panicked.*\n\n" -> ""
-// normalize-stderr-test "note: we would appreciate a bug report.*\n\n" -> ""
-// normalize-stderr-test "note: compiler flags.*\n\n" -> ""
-// normalize-stderr-test "note: rustc.*running on.*\n\n" -> ""
-// normalize-stderr-test "#.*\n" -> ""
-// normalize-stderr-test ".*delayed.*\n" -> ""
-
-// tracked in https://github.com/rust-lang/rust/issues/96572
-
+// compile-flags: --edition=2021
 #![feature(type_alias_impl_trait)]
 
 fn main() {
-    type T = impl Copy;
+    type T = impl Copy; //~ ERROR unconstrained opaque type
     let foo: T = (1u32, 2u32);
     let (a, b): (u32, u32) = foo;
 }
diff --git a/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.stderr b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.stderr
index 84d2705bf24..03b172e6de5 100644
--- a/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.stderr
+++ b/src/test/ui/type-alias-impl-trait/cross_inference_pattern_bug.stderr
@@ -1,32 +1,10 @@
-error: internal compiler error: no errors encountered even though `delay_span_bug` issued
-
-error: internal compiler error: broken MIR in DefId(0:3 ~ cross_inference_pattern_bug[646d]::main) ((_1.0: u32)): can't project out of PlaceTy { ty: main::T, variant_index: None }
-  --> $DIR/cross_inference_pattern_bug.rs:23:10
-   |
-LL |     let (a, b): (u32, u32) = foo;
-   |          ^
-   |
-
-error: internal compiler error: TyKind::Error constructed but no error reported
-   |
-
-error: internal compiler error: TyKind::Error constructed but no error reported
+error: unconstrained opaque type
+  --> $DIR/cross_inference_pattern_bug.rs:5:14
    |
-
-error: internal compiler error: broken MIR in DefId(0:3 ~ cross_inference_pattern_bug[646d]::main) ((_1.1: u32)): can't project out of PlaceTy { ty: main::T, variant_index: None }
-  --> $DIR/cross_inference_pattern_bug.rs:23:13
-   |
-LL |     let (a, b): (u32, u32) = foo;
-   |             ^
-   |
-
-error: internal compiler error: TyKind::Error constructed but no error reported
-   |
-
-error: internal compiler error: TyKind::Error constructed but no error reported
+LL |     type T = impl Copy;
+   |              ^^^^^^^^^
    |
+   = note: `T` must be used in combination with a concrete type within the same module
 
-thread 'rustc' panicked
+error: aborting due to previous error
 
-query stack during panic:
-end of query stack