Rollup merge of #56366 - alexreg:stabilise-self_in_typedefs, r=Centril

Stabilize self_in_typedefs feature

[**Tracking Issue**](https://github.com/rust-lang/rust/issues/49303)

r? @centril

11 files changed, 25 insertions, 82 deletions

diff --git a/src/doc/unstable-book/src/language-features/self-in-typedefs.md b/src/doc/unstable-book/src/language-features/self-in-typedefs.md
deleted file mode 100644
index 2416e85c17d..00000000000
--- a/src/doc/unstable-book/src/language-features/self-in-typedefs.md
+++ /dev/null
@@ -1,24 +0,0 @@
-# `self_in_typedefs`
-
-The tracking issue for this feature is: [#49303]
-
-[#49303]: https://github.com/rust-lang/rust/issues/49303
-
-------------------------
-
-The `self_in_typedefs` feature gate lets you use the special `Self` identifier
-in `struct`, `enum`, and `union` type definitions.
-
-A simple example is:
-
-```rust
-#![feature(self_in_typedefs)]
-
-enum List<T>
-where
-    Self: PartialOrd<Self> // can write `Self` instead of `List<T>`
-{
-    Nil,
-    Cons(T, Box<Self>) // likewise here
-}
-```
diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs
index c1d4643c240..fdac1e3b816 100644
--- a/src/librustc_resolve/lib.rs
+++ b/src/librustc_resolve/lib.rs
@@ -2373,13 +2373,9 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
         self.with_current_self_item(item, |this| {
             this.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
                 let item_def_id = this.definitions.local_def_id(item.id);
-                if this.session.features_untracked().self_in_typedefs {
-                    this.with_self_rib(Def::SelfTy(None, Some(item_def_id)), |this| {
-                        visit::walk_item(this, item);
-                    });
-                } else {
+                this.with_self_rib(Def::SelfTy(None, Some(item_def_id)), |this| {
                     visit::walk_item(this, item);
-                }
+                });
             });
         });
     }
@@ -3185,16 +3181,8 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
             if is_self_type(path, ns) {
                 __diagnostic_used!(E0411);
                 err.code(DiagnosticId::Error("E0411".into()));
-                let available_in = if this.session.features_untracked().self_in_typedefs {
-                    "impls, traits, and type definitions"
-                } else {
-                    "traits and impls"
-                };
-                err.span_label(span, format!("`Self` is only available in {}", available_in));
-                if this.current_self_item.is_some() && nightly_options::is_nightly_build() {
-                    err.help("add #![feature(self_in_typedefs)] to the crate attributes \
-                              to enable");
-                }
+                err.span_label(span, format!("`Self` is only available in impls, traits, \
+                                              and type definitions"));
                 return (err, Vec::new());
             }
             if is_self_value(path, ns) {
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index d0c4d1c7dce..1ced452e458 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -462,9 +462,6 @@ declare_features! (
     // Allows `use x::y;` to resolve through `self::x`, not just `::x`
     (active, uniform_paths, "1.30.0", Some(53130), None),
 
-    // Allows `Self` in type definitions
-    (active, self_in_typedefs, "1.30.0", Some(49303), None),
-
     // Allows unsized rvalues at arguments and parameters
     (active, unsized_locals, "1.30.0", Some(48055), None),
 
@@ -675,21 +672,23 @@ declare_features! (
     (accepted, extern_prelude, "1.30.0", Some(44660), None),
     // Parentheses in patterns
     (accepted, pattern_parentheses, "1.31.0", Some(51087), None),
-    // Allows the definition of `const fn` functions.
+    // Allows the definition of `const fn` functions
     (accepted, min_const_fn, "1.31.0", Some(53555), None),
     // Scoped lints
     (accepted, tool_lints, "1.31.0", Some(44690), None),
     // impl<I:Iterator> Iterator for &mut Iterator
     // impl Debug for Foo<'_>
     (accepted, impl_header_lifetime_elision, "1.31.0", Some(15872), None),
-    // `extern crate foo as bar;` puts `bar` into extern prelude.
+    // `extern crate foo as bar;` puts `bar` into extern prelude
     (accepted, extern_crate_item_prelude, "1.31.0", Some(55599), None),
     // Allows use of the :literal macro fragment specifier (RFC 1576)
     (accepted, macro_literal_matcher, "1.31.0", Some(35625), None),
     // Use `?` as the Kleene "at most one" operator
     (accepted, macro_at_most_once_rep, "1.32.0", Some(48075), None),
-    // Self struct constructor  (RFC 2302)
+    // `Self` struct constructor (RFC 2302)
     (accepted, self_struct_ctor, "1.32.0", Some(51994), None),
+    // `Self` in type definitions (RFC 2300)
+    (accepted, self_in_typedefs, "1.32.0", Some(49303), None),
 );
 
 // If you change this, please modify `src/doc/unstable-book` as well. You must
diff --git a/src/test/run-pass/self/self-in-typedefs.rs b/src/test/run-pass/self/self-in-typedefs.rs
index 92eccb47e18..84a7e18f91a 100644
--- a/src/test/run-pass/self/self-in-typedefs.rs
+++ b/src/test/run-pass/self/self-in-typedefs.rs
@@ -9,12 +9,11 @@
 // except according to those terms.
 
 // run-pass
-#![allow(unions_with_drop_fields)]
 
-#![feature(self_in_typedefs)]
 #![feature(untagged_unions)]
 
 #![allow(dead_code)]
+#![allow(unions_with_drop_fields)]
 
 enum A<'a, T: 'a>
 where
diff --git a/src/test/ui/error-codes/E0411.stderr b/src/test/ui/error-codes/E0411.stderr
index a5f2e3a7b93..4e85f651b55 100644
--- a/src/test/ui/error-codes/E0411.stderr
+++ b/src/test/ui/error-codes/E0411.stderr
@@ -2,7 +2,7 @@ error[E0411]: cannot find type `Self` in this scope
   --> $DIR/E0411.rs:12:6
    |
 LL |     <Self>::foo; //~ ERROR E0411
-   |      ^^^^ `Self` is only available in traits and impls
+   |      ^^^^ `Self` is only available in impls, traits, and type definitions
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/feature-gates/feature-gate-self_in_typedefs.rs b/src/test/ui/feature-gates/feature-gate-self_in_typedefs.rs
deleted file mode 100644
index 4b476a0a645..00000000000
--- a/src/test/ui/feature-gates/feature-gate-self_in_typedefs.rs
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-enum StackList<'a, T: 'a> {
-    Nil,
-    Cons(T, &'a Self)
-    //~^ ERROR cannot find type `Self` in this scope
-    //~| `Self` is only available in traits and impls
-}
-
-fn main() {}
diff --git a/src/test/ui/feature-gates/feature-gate-self_in_typedefs.stderr b/src/test/ui/feature-gates/feature-gate-self_in_typedefs.stderr
deleted file mode 100644
index ab04953f3e5..00000000000
--- a/src/test/ui/feature-gates/feature-gate-self_in_typedefs.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-error[E0411]: cannot find type `Self` in this scope
-  --> $DIR/feature-gate-self_in_typedefs.rs:13:17
-   |
-LL |     Cons(T, &'a Self)
-   |                 ^^^^ `Self` is only available in traits and impls
-   |
-   = help: add #![feature(self_in_typedefs)] to the crate attributes to enable
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0411`.
diff --git a/src/test/ui/issues/issue-36638.rs b/src/test/ui/issues/issue-36638.rs
index 5e43536ef3f..acb501c29fc 100644
--- a/src/test/ui/issues/issue-36638.rs
+++ b/src/test/ui/issues/issue-36638.rs
@@ -12,6 +12,7 @@
 
 struct Foo<Self>(Self);
 //~^ ERROR expected identifier, found keyword `Self`
+//~^^ ERROR E0392
 
 trait Bar<Self> {}
 //~^ ERROR expected identifier, found keyword `Self`
diff --git a/src/test/ui/issues/issue-36638.stderr b/src/test/ui/issues/issue-36638.stderr
index d111fb469bf..155eb170b09 100644
--- a/src/test/ui/issues/issue-36638.stderr
+++ b/src/test/ui/issues/issue-36638.stderr
@@ -5,10 +5,19 @@ LL | struct Foo<Self>(Self);
    |            ^^^^ expected identifier, found keyword
 
 error: expected identifier, found keyword `Self`
-  --> $DIR/issue-36638.rs:16:11
+  --> $DIR/issue-36638.rs:17:11
    |
 LL | trait Bar<Self> {}
    |           ^^^^ expected identifier, found keyword
 
-error: aborting due to 2 previous errors
+error[E0392]: parameter `Self` is never used
+  --> $DIR/issue-36638.rs:13:12
+   |
+LL | struct Foo<Self>(Self);
+   |            ^^^^ unused type parameter
+   |
+   = help: consider removing `Self` or using a marker such as `std::marker::PhantomData`
+
+error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0392`.
diff --git a/src/test/ui/resolve/issue-24968.stderr b/src/test/ui/resolve/issue-24968.stderr
index 9a1d5ea170e..cfb20340504 100644
--- a/src/test/ui/resolve/issue-24968.stderr
+++ b/src/test/ui/resolve/issue-24968.stderr
@@ -2,7 +2,7 @@ error[E0411]: cannot find type `Self` in this scope
   --> $DIR/issue-24968.rs:11:11
    |
 LL | fn foo(_: Self) {
-   |           ^^^^ `Self` is only available in traits and impls
+   |           ^^^^ `Self` is only available in impls, traits, and type definitions
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/resolve/resolve-self-in-impl-2.stderr b/src/test/ui/resolve/resolve-self-in-impl-2.stderr
index 183b9b66327..b3a8261bcfc 100644
--- a/src/test/ui/resolve/resolve-self-in-impl-2.stderr
+++ b/src/test/ui/resolve/resolve-self-in-impl-2.stderr
@@ -2,7 +2,7 @@ error[E0411]: expected trait, found self type `Self`
   --> $DIR/resolve-self-in-impl-2.rs:14:6
    |
 LL | impl Self for S {} //~ ERROR expected trait, found self type `Self`
-   |      ^^^^ `Self` is only available in traits and impls
+   |      ^^^^ `Self` is only available in impls, traits, and type definitions
 
 error[E0405]: cannot find trait `N` in `Self`
   --> $DIR/resolve-self-in-impl-2.rs:15:12