Auto merge of #84767 - scottmcm:try_trait_actual, r=lcnr

Implement the new desugaring from `try_trait_v2`

~~Currently blocked on https://github.com/rust-lang/rust/issues/84782, which has a PR in https://github.com/rust-lang/rust/pull/84811~~ Rebased atop that fix.

`try_trait_v2` tracking issue: https://github.com/rust-lang/rust/issues/84277

Unfortunately this is already touching a ton of things, so if you have suggestions for good ways to split it up, I'd be happy to hear them.  (The combination between the use in the library, the compiler changes, the corresponding diagnostic differences, even MIR tests mean that I don't really have a great plan for it other than trying to have decently-readable commits.

r? `@ghost`

~~(This probably shouldn't go in during the last week before the fork anyway.)~~ Fork happened.

3 files changed, 19 insertions, 19 deletions

diff --git a/src/test/ui/async-await/issue-61076.rs b/src/test/ui/async-await/issue-61076.rs
index 4a8e841b33d..9fe3313ee6c 100644
--- a/src/test/ui/async-await/issue-61076.rs
+++ b/src/test/ui/async-await/issue-61076.rs
@@ -42,7 +42,7 @@ async fn bar() -> Result<(), ()> {
     foo()?; //~ ERROR the `?` operator can only be applied to values that implement `Try`
     //~^ NOTE the `?` operator cannot be applied to type `impl Future`
     //~| HELP the trait `Try` is not implemented for `impl Future`
-    //~| NOTE required by `into_result`
+    //~| NOTE required by `branch`
     //~| HELP consider `await`ing on the `Future`
     //~| NOTE in this expansion of desugaring of operator `?`
     //~| NOTE in this expansion of desugaring of operator `?`
@@ -65,7 +65,7 @@ async fn baz() -> Result<(), ()> {
     t?; //~ ERROR the `?` operator can only be applied to values that implement `Try`
     //~^ NOTE the `?` operator cannot be applied to type `T`
     //~| HELP the trait `Try` is not implemented for `T`
-    //~| NOTE required by `into_result`
+    //~| NOTE required by `branch`
     //~| HELP consider `await`ing on the `Future`
     //~| NOTE in this expansion of desugaring of operator `?`
     //~| NOTE in this expansion of desugaring of operator `?`
diff --git a/src/test/ui/async-await/issue-61076.stderr b/src/test/ui/async-await/issue-61076.stderr
index fd00522fac7..ad661fb2833 100644
--- a/src/test/ui/async-await/issue-61076.stderr
+++ b/src/test/ui/async-await/issue-61076.stderr
@@ -5,7 +5,7 @@ LL |     foo()?;
    |     ^^^^^^ the `?` operator cannot be applied to type `impl Future`
    |
    = help: the trait `Try` is not implemented for `impl Future`
-   = note: required by `into_result`
+   = note: required by `branch`
 help: consider `await`ing on the `Future`
    |
 LL |     foo().await?;
@@ -18,7 +18,7 @@ LL |     t?;
    |     ^^ the `?` operator cannot be applied to type `T`
    |
    = help: the trait `Try` is not implemented for `T`
-   = note: required by `into_result`
+   = note: required by `branch`
 help: consider `await`ing on the `Future`
    |
 LL |     t.await?;
diff --git a/src/test/ui/async-await/try-on-option-in-async.stderr b/src/test/ui/async-await/try-on-option-in-async.stderr
index 8e7823f3571..a3f122a4663 100644
--- a/src/test/ui/async-await/try-on-option-in-async.stderr
+++ b/src/test/ui/async-await/try-on-option-in-async.stderr
@@ -1,47 +1,47 @@
-error[E0277]: the `?` operator can only be used in an async block that returns `Result` or `Option` (or another type that implements `Try`)
-  --> $DIR/try-on-option-in-async.rs:8:9
+error[E0277]: the `?` operator can only be used in an async block that returns `Result` or `Option` (or another type that implements `FromResidual`)
+  --> $DIR/try-on-option-in-async.rs:8:10
    |
 LL |       async {
    |  ___________-
 LL | |         let x: Option<u32> = None;
 LL | |         x?;
-   | |         ^^ cannot use the `?` operator in an async block that returns `{integer}`
+   | |          ^ cannot use the `?` operator in an async block that returns `{integer}`
 LL | |         22
 LL | |     }
    | |_____- this function should return `Result` or `Option` to accept `?`
    |
-   = help: the trait `Try` is not implemented for `{integer}`
-   = note: required by `from_error`
+   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `{integer}`
+   = note: required by `from_residual`
 
-error[E0277]: the `?` operator can only be used in an async closure that returns `Result` or `Option` (or another type that implements `Try`)
-  --> $DIR/try-on-option-in-async.rs:17:9
+error[E0277]: the `?` operator can only be used in an async closure that returns `Result` or `Option` (or another type that implements `FromResidual`)
+  --> $DIR/try-on-option-in-async.rs:17:10
    |
 LL |       let async_closure = async || {
    |  __________________________________-
 LL | |         let x: Option<u32> = None;
 LL | |         x?;
-   | |         ^^ cannot use the `?` operator in an async closure that returns `u32`
+   | |          ^ cannot use the `?` operator in an async closure that returns `u32`
 LL | |         22_u32
 LL | |     };
    | |_____- this function should return `Result` or `Option` to accept `?`
    |
-   = help: the trait `Try` is not implemented for `u32`
-   = note: required by `from_error`
+   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `u32`
+   = note: required by `from_residual`
 
-error[E0277]: the `?` operator can only be used in an async function that returns `Result` or `Option` (or another type that implements `Try`)
-  --> $DIR/try-on-option-in-async.rs:26:5
+error[E0277]: the `?` operator can only be used in an async function that returns `Result` or `Option` (or another type that implements `FromResidual`)
+  --> $DIR/try-on-option-in-async.rs:26:6
    |
 LL |   async fn an_async_function() -> u32 {
    |  _____________________________________-
 LL | |     let x: Option<u32> = None;
 LL | |     x?;
-   | |     ^^ cannot use the `?` operator in an async function that returns `u32`
+   | |      ^ cannot use the `?` operator in an async function that returns `u32`
 LL | |     22
 LL | | }
    | |_- this function should return `Result` or `Option` to accept `?`
    |
-   = help: the trait `Try` is not implemented for `u32`
-   = note: required by `from_error`
+   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `u32`
+   = note: required by `from_residual`
 
 error: aborting due to 3 previous errors