Switch library rustc_unimplemented to use `Self` and `This`

11 files changed, 67 insertions, 70 deletions

diff --git a/library/core/src/convert/mod.rs b/library/core/src/convert/mod.rs
index e1b10e1074d..aeafc1be359 100644
--- a/library/core/src/convert/mod.rs
+++ b/library/core/src/convert/mod.rs
@@ -575,7 +575,7 @@ pub trait Into<T>: Sized {
 #[rustc_diagnostic_item = "From"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented(on(
-    all(_Self = "&str", T = "alloc::string::String"),
+    all(Self = "&str", T = "alloc::string::String"),
     note = "to coerce a `{T}` into a `{Self}`, use `&*` as a prefix",
 ))]
 #[doc(search_unbox)]
diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 4f7f8a5b84d..5978cb660f6 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -856,10 +856,10 @@ impl Display for Arguments<'_> {
     on(
         crate_local,
         label = "`{Self}` cannot be formatted using `{{:?}}`",
-        note = "add `#[derive(Debug)]` to `{Self}` or manually `impl {Debug} for {Self}`"
+        note = "add `#[derive(Debug)]` to `{Self}` or manually `impl {This} for {Self}`"
     ),
-    message = "`{Self}` doesn't implement `{Debug}`",
-    label = "`{Self}` cannot be formatted using `{{:?}}` because it doesn't implement `{Debug}`"
+    message = "`{Self}` doesn't implement `{This}`",
+    label = "`{Self}` cannot be formatted using `{{:?}}` because it doesn't implement `{This}`"
 )]
 #[doc(alias = "{:?}")]
 #[rustc_diagnostic_item = "Debug"]
@@ -969,12 +969,12 @@ pub use macros::Debug;
 /// ```
 #[rustc_on_unimplemented(
     on(
-        any(_Self = "std::path::Path", _Self = "std::path::PathBuf"),
+        any(Self = "std::path::Path", Self = "std::path::PathBuf"),
         label = "`{Self}` cannot be formatted with the default formatter; call `.display()` on it",
         note = "call `.display()` or `.to_string_lossy()` to safely print paths, \
                 as they may contain non-Unicode data"
     ),
-    message = "`{Self}` doesn't implement `{Display}`",
+    message = "`{Self}` doesn't implement `{This}`",
     label = "`{Self}` cannot be formatted with the default formatter",
     note = "in format strings you may be able to use `{{:?}}` (or {{:#?}} for pretty-print) instead"
 )]
diff --git a/library/core/src/iter/traits/collect.rs b/library/core/src/iter/traits/collect.rs
index 97bb21c8a36..3bc9cff8072 100644
--- a/library/core/src/iter/traits/collect.rs
+++ b/library/core/src/iter/traits/collect.rs
@@ -97,32 +97,32 @@ use super::TrustedLen;
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented(
     on(
-        _Self = "&[{A}]",
+        Self = "&[{A}]",
         message = "a slice of type `{Self}` cannot be built since we need to store the elements somewhere",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        all(A = "{integer}", any(_Self = "&[{integral}]",)),
+        all(A = "{integer}", any(Self = "&[{integral}]",)),
         message = "a slice of type `{Self}` cannot be built since we need to store the elements somewhere",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        _Self = "[{A}]",
+        Self = "[{A}]",
         message = "a slice of type `{Self}` cannot be built since `{Self}` has no definite size",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        all(A = "{integer}", any(_Self = "[{integral}]",)),
+        all(A = "{integer}", any(Self = "[{integral}]",)),
         message = "a slice of type `{Self}` cannot be built since `{Self}` has no definite size",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        _Self = "[{A}; _]",
+        Self = "[{A}; _]",
         message = "an array of type `{Self}` cannot be built directly from an iterator",
         label = "try collecting into a `Vec<{A}>`, then using `.try_into()`",
     ),
     on(
-        all(A = "{integer}", any(_Self = "[{integral}; _]",)),
+        all(A = "{integer}", any(Self = "[{integral}; _]",)),
         message = "an array of type `{Self}` cannot be built directly from an iterator",
         label = "try collecting into a `Vec<{A}>`, then using `.try_into()`",
     ),
@@ -239,41 +239,38 @@ pub trait FromIterator<A>: Sized {
 #[rustc_diagnostic_item = "IntoIterator"]
 #[rustc_on_unimplemented(
     on(
-        _Self = "core::ops::range::RangeTo<Idx>",
+        Self = "core::ops::range::RangeTo<Idx>",
         label = "if you meant to iterate until a value, add a starting value",
         note = "`..end` is a `RangeTo`, which cannot be iterated on; you might have meant to have a \
               bounded `Range`: `0..end`"
     ),
     on(
-        _Self = "core::ops::range::RangeToInclusive<Idx>",
+        Self = "core::ops::range::RangeToInclusive<Idx>",
         label = "if you meant to iterate until a value (including it), add a starting value",
         note = "`..=end` is a `RangeToInclusive`, which cannot be iterated on; you might have meant \
               to have a bounded `RangeInclusive`: `0..=end`"
     ),
     on(
-        _Self = "[]",
+        Self = "[]",
         label = "`{Self}` is not an iterator; try calling `.into_iter()` or `.iter()`"
     ),
-    on(_Self = "&[]", label = "`{Self}` is not an iterator; try calling `.iter()`"),
+    on(Self = "&[]", label = "`{Self}` is not an iterator; try calling `.iter()`"),
     on(
-        _Self = "alloc::vec::Vec<T, A>",
+        Self = "alloc::vec::Vec<T, A>",
         label = "`{Self}` is not an iterator; try calling `.into_iter()` or `.iter()`"
     ),
+    on(Self = "&str", label = "`{Self}` is not an iterator; try calling `.chars()` or `.bytes()`"),
     on(
-        _Self = "&str",
+        Self = "alloc::string::String",
         label = "`{Self}` is not an iterator; try calling `.chars()` or `.bytes()`"
     ),
     on(
-        _Self = "alloc::string::String",
-        label = "`{Self}` is not an iterator; try calling `.chars()` or `.bytes()`"
-    ),
-    on(
-        _Self = "{integral}",
+        Self = "{integral}",
         note = "if you want to iterate between `start` until a value `end`, use the exclusive range \
               syntax `start..end` or the inclusive range syntax `start..=end`"
     ),
     on(
-        _Self = "{float}",
+        Self = "{float}",
         note = "if you want to iterate between `start` until a value `end`, use the exclusive range \
               syntax `start..end` or the inclusive range syntax `start..=end`"
     ),
diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs
index d1e71f0e60f..cf85bdb1352 100644
--- a/library/core/src/iter/traits/iterator.rs
+++ b/library/core/src/iter/traits/iterator.rs
@@ -22,11 +22,11 @@ fn _assert_is_dyn_compatible(_: &dyn Iterator<Item = ()>) {}
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented(
     on(
-        _Self = "core::ops::range::RangeTo<Idx>",
+        Self = "core::ops::range::RangeTo<Idx>",
         note = "you might have meant to use a bounded `Range`"
     ),
     on(
-        _Self = "core::ops::range::RangeToInclusive<Idx>",
+        Self = "core::ops::range::RangeToInclusive<Idx>",
         note = "you might have meant to use a bounded `RangeInclusive`"
     ),
     label = "`{Self}` is not an iterator",
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index f33b8d188d8..700fb0f386e 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -550,72 +550,72 @@ pub trait BikeshedGuaranteedNoDrop {}
 #[lang = "sync"]
 #[rustc_on_unimplemented(
     on(
-        _Self = "core::cell::once::OnceCell<T>",
+        Self = "core::cell::once::OnceCell<T>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::OnceLock` instead"
     ),
     on(
-        _Self = "core::cell::Cell<u8>",
+        Self = "core::cell::Cell<u8>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU8` instead",
     ),
     on(
-        _Self = "core::cell::Cell<u16>",
+        Self = "core::cell::Cell<u16>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU16` instead",
     ),
     on(
-        _Self = "core::cell::Cell<u32>",
+        Self = "core::cell::Cell<u32>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU32` instead",
     ),
     on(
-        _Self = "core::cell::Cell<u64>",
+        Self = "core::cell::Cell<u64>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU64` instead",
     ),
     on(
-        _Self = "core::cell::Cell<usize>",
+        Self = "core::cell::Cell<usize>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicUsize` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i8>",
+        Self = "core::cell::Cell<i8>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI8` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i16>",
+        Self = "core::cell::Cell<i16>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI16` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i32>",
+        Self = "core::cell::Cell<i32>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI32` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i64>",
+        Self = "core::cell::Cell<i64>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI64` instead",
     ),
     on(
-        _Self = "core::cell::Cell<isize>",
+        Self = "core::cell::Cell<isize>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicIsize` instead",
     ),
     on(
-        _Self = "core::cell::Cell<bool>",
+        Self = "core::cell::Cell<bool>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicBool` instead",
     ),
     on(
         all(
-            _Self = "core::cell::Cell<T>",
-            not(_Self = "core::cell::Cell<u8>"),
-            not(_Self = "core::cell::Cell<u16>"),
-            not(_Self = "core::cell::Cell<u32>"),
-            not(_Self = "core::cell::Cell<u64>"),
-            not(_Self = "core::cell::Cell<usize>"),
-            not(_Self = "core::cell::Cell<i8>"),
-            not(_Self = "core::cell::Cell<i16>"),
-            not(_Self = "core::cell::Cell<i32>"),
-            not(_Self = "core::cell::Cell<i64>"),
-            not(_Self = "core::cell::Cell<isize>"),
-            not(_Self = "core::cell::Cell<bool>")
+            Self = "core::cell::Cell<T>",
+            not(Self = "core::cell::Cell<u8>"),
+            not(Self = "core::cell::Cell<u16>"),
+            not(Self = "core::cell::Cell<u32>"),
+            not(Self = "core::cell::Cell<u64>"),
+            not(Self = "core::cell::Cell<usize>"),
+            not(Self = "core::cell::Cell<i8>"),
+            not(Self = "core::cell::Cell<i16>"),
+            not(Self = "core::cell::Cell<i32>"),
+            not(Self = "core::cell::Cell<i64>"),
+            not(Self = "core::cell::Cell<isize>"),
+            not(Self = "core::cell::Cell<bool>")
         ),
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock`",
     ),
     on(
-        _Self = "core::cell::RefCell<T>",
+        Self = "core::cell::RefCell<T>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` instead",
     ),
     message = "`{Self}` cannot be shared between threads safely",
diff --git a/library/core/src/ops/arith.rs b/library/core/src/ops/arith.rs
index 54d79beca95..098ce4531f0 100644
--- a/library/core/src/ops/arith.rs
+++ b/library/core/src/ops/arith.rs
@@ -67,8 +67,8 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
 #[rustc_on_unimplemented(
-    on(all(_Self = "{integer}", Rhs = "{float}"), message = "cannot add a float to an integer",),
-    on(all(_Self = "{float}", Rhs = "{integer}"), message = "cannot add an integer to a float",),
+    on(all(Self = "{integer}", Rhs = "{float}"), message = "cannot add a float to an integer",),
+    on(all(Self = "{float}", Rhs = "{integer}"), message = "cannot add an integer to a float",),
     message = "cannot add `{Rhs}` to `{Self}`",
     label = "no implementation for `{Self} + {Rhs}`",
     append_const_msg
diff --git a/library/core/src/ops/function.rs b/library/core/src/ops/function.rs
index e9014458b48..df48c104410 100644
--- a/library/core/src/ops/function.rs
+++ b/library/core/src/ops/function.rs
@@ -62,7 +62,7 @@ use crate::marker::Tuple;
         note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
     ),
     on(
-        _Self = "unsafe fn",
+        Self = "unsafe fn",
         note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
         label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
@@ -149,7 +149,7 @@ pub trait Fn<Args: Tuple>: FnMut<Args> {
         note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
     ),
     on(
-        _Self = "unsafe fn",
+        Self = "unsafe fn",
         note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
         label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
@@ -228,7 +228,7 @@ pub trait FnMut<Args: Tuple>: FnOnce<Args> {
         note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
     ),
     on(
-        _Self = "unsafe fn",
+        Self = "unsafe fn",
         note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
         label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
diff --git a/library/core/src/ops/index.rs b/library/core/src/ops/index.rs
index 46e19bed43a..8092fa9eb2f 100644
--- a/library/core/src/ops/index.rs
+++ b/library/core/src/ops/index.rs
@@ -144,17 +144,17 @@ pub trait Index<Idx: ?Sized> {
 #[lang = "index_mut"]
 #[rustc_on_unimplemented(
     on(
-        _Self = "&str",
+        Self = "&str",
         note = "you can use `.chars().nth()` or `.bytes().nth()`
 see chapter in The Book <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
     ),
     on(
-        _Self = "str",
+        Self = "str",
         note = "you can use `.chars().nth()` or `.bytes().nth()`
 see chapter in The Book <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
     ),
     on(
-        _Self = "alloc::string::String",
+        Self = "alloc::string::String",
         note = "you can use `.chars().nth()` or `.bytes().nth()`
 see chapter in The Book <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
     ),
diff --git a/library/core/src/ops/try_trait.rs b/library/core/src/ops/try_trait.rs
index 3ba2957526f..bac8ffb074b 100644
--- a/library/core/src/ops/try_trait.rs
+++ b/library/core/src/ops/try_trait.rs
@@ -117,12 +117,12 @@ use crate::ops::ControlFlow;
     on(
         all(from_desugaring = "TryBlock"),
         message = "a `try` block must return `Result` or `Option` \
-                    (or another type that implements `{Try}`)",
+                    (or another type that implements `{This}`)",
         label = "could not wrap the final value of the block as `{Self}` doesn't implement `Try`",
     ),
     on(
         all(from_desugaring = "QuestionMark"),
-        message = "the `?` operator can only be applied to values that implement `{Try}`",
+        message = "the `?` operator can only be applied to values that implement `{This}`",
         label = "the `?` operator cannot be applied to type `{Self}`"
     )
 )]
@@ -226,7 +226,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::result::Result<T, E>",
+            Self = "core::result::Result<T, E>",
             R = "core::option::Option<core::convert::Infallible>",
         ),
         message = "the `?` operator can only be used on `Result`s, not `Option`s, \
@@ -237,7 +237,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::result::Result<T, E>",
+            Self = "core::result::Result<T, E>",
         ),
         // There's a special error message in the trait selection code for
         // `From` in `?`, so this is not shown for result-in-result errors,
@@ -250,7 +250,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::option::Option<T>",
+            Self = "core::option::Option<T>",
             R = "core::result::Result<T, E>",
         ),
         message = "the `?` operator can only be used on `Option`s, not `Result`s, \
@@ -261,7 +261,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::option::Option<T>",
+            Self = "core::option::Option<T>",
         ),
         // `Option`-in-`Option` always works, as there's only one possible
         // residual, so this can also be phrased strongly.
@@ -273,7 +273,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::ops::control_flow::ControlFlow<B, C>",
+            Self = "core::ops::control_flow::ControlFlow<B, C>",
             R = "core::ops::control_flow::ControlFlow<B, C>",
         ),
         message = "the `?` operator in {ItemContext} that returns `ControlFlow<B, _>` \
@@ -285,7 +285,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::ops::control_flow::ControlFlow<B, C>",
+            Self = "core::ops::control_flow::ControlFlow<B, C>",
             // `R` is not a `ControlFlow`, as that case was matched previously
         ),
         message = "the `?` operator can only be used on `ControlFlow`s \
@@ -297,7 +297,7 @@ pub trait Try: FromResidual {
         all(from_desugaring = "QuestionMark"),
         message = "the `?` operator can only be used in {ItemContext} \
                     that returns `Result` or `Option` \
-                    (or another type that implements `{FromResidual}`)",
+                    (or another type that implements `{This}`)",
         label = "cannot use the `?` operator in {ItemContext} that returns `{Self}`",
         parent_label = "this function should return `Result` or `Option` to accept `?`"
     ),
diff --git a/library/core/src/slice/index.rs b/library/core/src/slice/index.rs
index aafa19c0dd3..409bad9f061 100644
--- a/library/core/src/slice/index.rs
+++ b/library/core/src/slice/index.rs
@@ -161,7 +161,7 @@ mod private_slice_index {
 #[rustc_on_unimplemented(
     on(T = "str", label = "string indices are ranges of `usize`",),
     on(
-        all(any(T = "str", T = "&str", T = "alloc::string::String"), _Self = "{integer}"),
+        all(any(T = "str", T = "&str", T = "alloc::string::String"), Self = "{integer}"),
         note = "you can use `.chars().nth()` or `.bytes().nth()`\n\
                 for more information, see chapter 8 in The Book: \
                 <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
diff --git a/library/std/src/process.rs b/library/std/src/process.rs
index df6b9a6e563..359e2082072 100644
--- a/library/std/src/process.rs
+++ b/library/std/src/process.rs
@@ -2532,7 +2532,7 @@ pub fn id() -> u32 {
 #[rustc_on_unimplemented(on(
     cause = "MainFunctionType",
     message = "`main` has invalid return type `{Self}`",
-    label = "`main` can only return types that implement `{Termination}`"
+    label = "`main` can only return types that implement `{This}`"
 ))]
 pub trait Termination {
     /// Is called to get the representation of the value as status code.