Remove the option-to-result back-compat hack

Author: scottmcm

library/core/src/result.rs

@@ -1650,28 +1650,3 @@ impl<T, E, F: From<E>> ops::FromResidual<Result<!, E>> for Result<T, F> {
         }
     }
 }
-
-mod sadness {
-    use super::*;
-
-    /// This is a remnant of the old `NoneError` which is never going to be stabilized.
-    /// It's here as a snapshot of an oversight that allowed this to work in the past,
-    /// so we're stuck supporting it even though we'd really rather not.
-    #[unstable(feature = "legacy_try_trait", issue = "none")]
-    #[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
-    pub struct PleaseCallTheOkOrMethodToUseQuestionMarkOnOptionsInAMethodThatReturnsResult;
-
-    #[unstable(feature = "try_trait_v2", issue = "42327")]
-    impl<T, E> ops::FromResidual<Option<!>> for Result<T, E>
-    where
-        E: From<PleaseCallTheOkOrMethodToUseQuestionMarkOnOptionsInAMethodThatReturnsResult>,
-    {
-        fn from_residual(x: Option<!>) -> Self {
-            match x {
-                None => Err(From::from(
-                    PleaseCallTheOkOrMethodToUseQuestionMarkOnOptionsInAMethodThatReturnsResult,
-                )),
-            }
-        }
-    }
-}

src/test/ui/option-to-result.rs

@@ -2,7 +2,7 @@ fn main(){ }
 
 fn test_result() -> Result<(),()> {
     let a:Option<()> = Some(());
-    a?;//~ ERROR `?` couldn't convert the error to `()`
+    a?;//~ ERROR the `?` operator can only be used in a function that returns `Result` or `Option`
     Ok(())
 }
 

src/test/ui/option-to-result.stderr

@@ -1,14 +1,15 @@
-error[E0277]: `?` couldn't convert the error to `()`
+error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
   --> $DIR/option-to-result.rs:5:5
    |
-LL | fn test_result() -> Result<(),()> {
-   |                     ------------- expected `()` because of this
-LL |     let a:Option<()> = Some(());
-LL |     a?;
-   |     ^^ the trait `From<result::sadness::PleaseCallTheOkOrMethodToUseQuestionMarkOnOptionsInAMethodThatReturnsResult>` is not implemented for `()`
+LL | / fn test_result() -> Result<(),()> {
+LL | |     let a:Option<()> = Some(());
+LL | |     a?;
+   | |     ^^ cannot use the `?` operator in a function that returns `Result<(), ()>`
+LL | |     Ok(())
+LL | | }
+   | |_- this function should return `Result` or `Option` to accept `?`
    |
-   = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
-   = note: required because of the requirements on the impl of `FromResidual<Option<!>>` for `Result<(), ()>`
+   = help: the trait `FromResidual<Option<!>>` is not implemented for `Result<(), ()>`
    = note: required by `from_residual`
 
 error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)

src/test/ui/try-block/try-block-bad-type.rs

@@ -15,7 +15,7 @@ pub fn main() {
     let res: Result<i32, i32> = try { }; //~ ERROR type mismatch
 
     let res: () = try { };
-    //~^ ERROR the trait bound `(): Try` is not satisfied
+    //~^ ERROR the trait bound `(): Try2021` is not satisfied
 
-    let res: i32 = try { 5 }; //~ ERROR the trait bound `i32: Try` is not satisfied
+    let res: i32 = try { 5 }; //~ ERROR the trait bound `i32: Try2021` is not satisfied
 }

src/test/ui/try-block/try-block-bad-type.stderr

@@ -10,31 +10,31 @@ LL |         Err("")?;
    = note: required because of the requirements on the impl of `FromResidual<Result<!, &str>>` for `Result<u32, TryFromSliceError>`
    = note: required by `from_residual`
 
-error[E0271]: type mismatch resolving `<Result<i32, i32> as Try>::Ok == &str`
+error[E0271]: type mismatch resolving `<Result<i32, i32> as Try2021>::Ok == &str`
   --> $DIR/try-block-bad-type.rs:12:9
    |
 LL |         ""
    |         ^^ expected `i32`, found `&str`
 
-error[E0271]: type mismatch resolving `<Result<i32, i32> as Try>::Ok == ()`
+error[E0271]: type mismatch resolving `<Result<i32, i32> as Try2021>::Ok == ()`
   --> $DIR/try-block-bad-type.rs:15:39
    |
 LL |     let res: Result<i32, i32> = try { };
    |                                       ^ expected `i32`, found `()`
 
-error[E0277]: the trait bound `(): Try` is not satisfied
+error[E0277]: the trait bound `(): Try2021` is not satisfied
   --> $DIR/try-block-bad-type.rs:17:25
    |
 LL |     let res: () = try { };
-   |                         ^ the trait `Try` is not implemented for `()`
+   |                         ^ the trait `Try2021` is not implemented for `()`
    |
    = note: required by `from_output`
 
-error[E0277]: the trait bound `i32: Try` is not satisfied
+error[E0277]: the trait bound `i32: Try2021` is not satisfied
   --> $DIR/try-block-bad-type.rs:20:26
    |
 LL |     let res: i32 = try { 5 };
-   |                          ^ the trait `Try` is not implemented for `i32`
+   |                          ^ the trait `Try2021` is not implemented for `i32`
    |
    = note: required by `from_output`
 

src/test/ui/try-trait/try-on-option-in-result-method.rs

@@ -4,7 +4,7 @@ fn main() {}
 
 fn foo() -> Result<u32, ()> {
     let x: Option<u32> = None;
-    x?; //~ ERROR `?` couldn't convert the error to `()`
+    x?; //~ ERROR the `?` operator
     Ok(22)
 }
 

src/test/ui/try-trait/try-on-option.rs

@@ -1,14 +1,15 @@
-error[E0277]: `?` couldn't convert the error to `()`
+error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
   --> $DIR/try-on-option.rs:7:5
    |
-LL | fn foo() -> Result<u32, ()> {
-   |             --------------- expected `()` because of this
-LL |     let x: Option<u32> = None;
-LL |     x?;
-   |     ^^ the trait `From<result::sadness::PleaseCallTheOkOrMethodToUseQuestionMarkOnOptionsInAMethodThatReturnsResult>` is not implemented for `()`
+LL | / fn foo() -> Result<u32, ()> {
+LL | |     let x: Option<u32> = None;
+LL | |     x?;
+   | |     ^^ cannot use the `?` operator in a function that returns `Result<u32, ()>`
+LL | |     Ok(22)
+LL | | }
+   | |_- this function should return `Result` or `Option` to accept `?`
    |
-   = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
-   = note: required because of the requirements on the impl of `FromResidual<Option<!>>` for `Result<u32, ()>`
+   = help: the trait `FromResidual<Option<!>>` is not implemented for `Result<u32, ()>`
    = note: required by `from_residual`
 
 error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)