From 7a62f29f3171767090949778ce0f161e930706b9 Mon Sep 17 00:00:00 2001
From: Deadbeef <ent3rm4n@gmail.com>
Date: Sun, 4 Jul 2021 14:52:17 +0800
Subject: [PATCH] Stabilize `arbitrary_enum_discriminant`

---
 compiler/rustc_ast_passes/src/feature_gate.rs | 64 +------------------
 .../src/error_codes/E0732.md                  |  4 --
 compiler/rustc_feature/src/accepted.rs        |  2 +
 compiler/rustc_feature/src/active.rs          |  3 -
 compiler/rustc_typeck/src/check/check.rs      |  2 +-
 .../arbitrary-enum-discriminant.md            | 37 -----------
 .../arbitrary_enum_discriminant-no-repr.rs    |  1 -
 ...arbitrary_enum_discriminant-no-repr.stderr |  2 +-
 .../arbitrary_enum_discriminant.rs            |  2 +-
 .../enum-discriminant/discriminant_value.rs   |  2 +-
 ...eature-gate-arbitrary_enum_discriminant.rs | 10 ---
 ...re-gate-arbitrary_enum_discriminant.stderr | 36 -----------
 .../issue-70453-generics-in-discr-ice-2.rs    |  2 +-
 .../issue-70453-polymorphic-ctfe.rs           |  2 +-
 .../issue-70509-partial_eq.rs                 |  2 +-
 .../issue-70509-partial_eq.stderr             |  2 +-
 .../intrinsics/panic-uninitialized-zeroed.rs  |  2 +-
 src/test/ui/parser/issue-17383.rs             |  7 --
 src/test/ui/parser/issue-17383.stderr         | 15 -----
 .../ui/parser/tag-variant-disr-non-nullary.rs | 12 ----
 .../tag-variant-disr-non-nullary.stderr       | 25 --------
 21 files changed, 13 insertions(+), 221 deletions(-)
 delete mode 100644 src/doc/unstable-book/src/language-features/arbitrary-enum-discriminant.md
 delete mode 100644 src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.rs
 delete mode 100644 src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.stderr
 delete mode 100644 src/test/ui/parser/issue-17383.rs
 delete mode 100644 src/test/ui/parser/issue-17383.stderr
 delete mode 100644 src/test/ui/parser/tag-variant-disr-non-nullary.rs
 delete mode 100644 src/test/ui/parser/tag-variant-disr-non-nullary.stderr

diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs
index 3e757e3843e38..1652c6809349f 100644
--- a/compiler/rustc_ast_passes/src/feature_gate.rs
+++ b/compiler/rustc_ast_passes/src/feature_gate.rs
@@ -1,11 +1,11 @@
 use rustc_ast as ast;
 use rustc_ast::visit::{self, AssocCtxt, FnCtxt, FnKind, Visitor};
 use rustc_ast::{AssocTyConstraint, AssocTyConstraintKind, NodeId};
-use rustc_ast::{PatKind, RangeEnd, VariantData};
+use rustc_ast::{PatKind, RangeEnd};
 use rustc_errors::struct_span_err;
 use rustc_feature::{AttributeGate, BUILTIN_ATTRIBUTE_MAP};
 use rustc_feature::{Features, GateIssue};
-use rustc_session::parse::{feature_err, feature_err_issue};
+use rustc_session::parse::feature_err_issue;
 use rustc_session::Session;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::sym;
@@ -218,46 +218,6 @@ impl<'a> PostExpansionVisitor<'a> {
         }
     }
 
-    fn maybe_report_invalid_custom_discriminants(&self, variants: &[ast::Variant]) {
-        let has_fields = variants.iter().any(|variant| match variant.data {
-            VariantData::Tuple(..) | VariantData::Struct(..) => true,
-            VariantData::Unit(..) => false,
-        });
-
-        let discriminant_spans = variants
-            .iter()
-            .filter(|variant| match variant.data {
-                VariantData::Tuple(..) | VariantData::Struct(..) => false,
-                VariantData::Unit(..) => true,
-            })
-            .filter_map(|variant| variant.disr_expr.as_ref().map(|c| c.value.span))
-            .collect::<Vec<_>>();
-
-        if !discriminant_spans.is_empty() && has_fields {
-            let mut err = feature_err(
-                &self.sess.parse_sess,
-                sym::arbitrary_enum_discriminant,
-                discriminant_spans.clone(),
-                "custom discriminant values are not allowed in enums with tuple or struct variants",
-            );
-            for sp in discriminant_spans {
-                err.span_label(sp, "disallowed custom discriminant");
-            }
-            for variant in variants.iter() {
-                match &variant.data {
-                    VariantData::Struct(..) => {
-                        err.span_label(variant.span, "struct variant defined here");
-                    }
-                    VariantData::Tuple(..) => {
-                        err.span_label(variant.span, "tuple variant defined here");
-                    }
-                    VariantData::Unit(..) => {}
-                }
-            }
-            err.emit();
-        }
-    }
-
     fn check_gat(&self, generics: &ast::Generics, span: Span) {
         if !generics.params.is_empty() {
             gate_feature_post!(
@@ -410,26 +370,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 }
             }
 
-            ast::ItemKind::Enum(ast::EnumDef { ref variants, .. }, ..) => {
-                for variant in variants {
-                    match (&variant.data, &variant.disr_expr) {
-                        (ast::VariantData::Unit(..), _) => {}
-                        (_, Some(disr_expr)) => gate_feature_post!(
-                            &self,
-                            arbitrary_enum_discriminant,
-                            disr_expr.value.span,
-                            "discriminants on non-unit variants are experimental"
-                        ),
-                        _ => {}
-                    }
-                }
-
-                let has_feature = self.features.arbitrary_enum_discriminant;
-                if !has_feature && !i.span.allows_unstable(sym::arbitrary_enum_discriminant) {
-                    self.maybe_report_invalid_custom_discriminants(&variants);
-                }
-            }
-
             ast::ItemKind::Impl(box ast::ImplKind {
                 polarity, defaultness, ref of_trait, ..
             }) => {
diff --git a/compiler/rustc_error_codes/src/error_codes/E0732.md b/compiler/rustc_error_codes/src/error_codes/E0732.md
index 7347e6654c5b3..9536fdbf0df87 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0732.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0732.md
@@ -3,8 +3,6 @@ An `enum` with a discriminant must specify a `#[repr(inttype)]`.
 Erroneous code example:
 
 ```compile_fail,E0732
-#![feature(arbitrary_enum_discriminant)]
-
 enum Enum { // error!
     Unit = 1,
     Tuple() = 2,
@@ -20,8 +18,6 @@ is a well-defined way to extract a variant's discriminant from a value;
 for instance:
 
 ```
-#![feature(arbitrary_enum_discriminant)]
-
 #[repr(u8)]
 enum Enum {
     Unit = 3,
diff --git a/compiler/rustc_feature/src/accepted.rs b/compiler/rustc_feature/src/accepted.rs
index 9ce5a149697f7..f3c710e0f6af3 100644
--- a/compiler/rustc_feature/src/accepted.rs
+++ b/compiler/rustc_feature/src/accepted.rs
@@ -294,6 +294,8 @@ declare_features! (
     (accepted, const_fn_transmute, "1.56.0", Some(53605), None),
     /// Allows accessing fields of unions inside `const` functions.
     (accepted, const_fn_union, "1.56.0", Some(51909), None),
+    /// Allows explicit discriminants on non-unit enum variants.
+    (accepted, arbitrary_enum_discriminant, "1.56.0", Some(60553), None),
 
     // -------------------------------------------------------------------------
     // feature-group-end: accepted features
diff --git a/compiler/rustc_feature/src/active.rs b/compiler/rustc_feature/src/active.rs
index 3cb1dd170386b..6f838a4cfc999 100644
--- a/compiler/rustc_feature/src/active.rs
+++ b/compiler/rustc_feature/src/active.rs
@@ -479,9 +479,6 @@ declare_features! (
     /// Allows #[repr(transparent)] on unions (RFC 2645).
     (active, transparent_unions, "1.37.0", Some(60405), None),
 
-    /// Allows explicit discriminants on non-unit enum variants.
-    (active, arbitrary_enum_discriminant, "1.37.0", Some(60553), None),
-
     /// Allows `async || body` closures.
     (active, async_closure, "1.37.0", Some(62290), None),
 
diff --git a/compiler/rustc_typeck/src/check/check.rs b/compiler/rustc_typeck/src/check/check.rs
index b5db3331d0447..a7bd9fd4020d3 100644
--- a/compiler/rustc_typeck/src/check/check.rs
+++ b/compiler/rustc_typeck/src/check/check.rs
@@ -1442,7 +1442,7 @@ fn check_enum<'tcx>(
         }
     }
 
-    if tcx.adt_def(def_id).repr.int.is_none() && tcx.features().arbitrary_enum_discriminant {
+    if tcx.adt_def(def_id).repr.int.is_none() {
         let is_unit = |var: &hir::Variant<'_>| matches!(var.data, hir::VariantData::Unit(..));
 
         let has_disr = |var: &hir::Variant<'_>| var.disr_expr.is_some();
diff --git a/src/doc/unstable-book/src/language-features/arbitrary-enum-discriminant.md b/src/doc/unstable-book/src/language-features/arbitrary-enum-discriminant.md
deleted file mode 100644
index e0bb782270e22..0000000000000
--- a/src/doc/unstable-book/src/language-features/arbitrary-enum-discriminant.md
+++ /dev/null
@@ -1,37 +0,0 @@
-# `arbitrary_enum_discriminant`
-
-The tracking issue for this feature is: [#60553]
-
-[#60553]: https://github.com/rust-lang/rust/issues/60553
-
-------------------------
-
-The `arbitrary_enum_discriminant` feature permits tuple-like and
-struct-like enum variants with `#[repr(<int-type>)]` to have explicit discriminants.
-
-## Examples
-
-```rust
-#![feature(arbitrary_enum_discriminant)]
-
-#[allow(dead_code)]
-#[repr(u8)]
-enum Enum {
-    Unit = 3,
-    Tuple(u16) = 2,
-    Struct {
-        a: u8,
-        b: u16,
-    } = 1,
-}
-
-impl Enum {
-    fn tag(&self) -> u8 {
-        unsafe { *(self as *const Self as *const u8) }
-    }
-}
-
-assert_eq!(3, Enum::Unit.tag());
-assert_eq!(2, Enum::Tuple(5).tag());
-assert_eq!(1, Enum::Struct{a: 7, b: 11}.tag());
-```
diff --git a/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.rs b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.rs
index 4da7b5ab24b29..a6e5f70fdefa6 100644
--- a/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.rs
+++ b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.rs
@@ -1,5 +1,4 @@
 #![crate_type="lib"]
-#![feature(arbitrary_enum_discriminant)]
 
 enum Enum {
 //~^ ERROR `#[repr(inttype)]` must be specified
diff --git a/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.stderr b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.stderr
index 2db5372da0c6e..7af063c591d56 100644
--- a/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.stderr
+++ b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.stderr
@@ -1,5 +1,5 @@
 error[E0732]: `#[repr(inttype)]` must be specified
-  --> $DIR/arbitrary_enum_discriminant-no-repr.rs:4:1
+  --> $DIR/arbitrary_enum_discriminant-no-repr.rs:3:1
    |
 LL | / enum Enum {
 LL | |
diff --git a/src/test/ui/enum-discriminant/arbitrary_enum_discriminant.rs b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant.rs
index f2270602d87eb..360bddb7bd1e4 100644
--- a/src/test/ui/enum-discriminant/arbitrary_enum_discriminant.rs
+++ b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant.rs
@@ -1,5 +1,5 @@
 // run-pass
-#![feature(arbitrary_enum_discriminant, const_raw_ptr_deref, test)]
+#![feature(const_raw_ptr_deref, test)]
 
 extern crate test;
 
diff --git a/src/test/ui/enum-discriminant/discriminant_value.rs b/src/test/ui/enum-discriminant/discriminant_value.rs
index eb60aaf4b2d04..7ed1d9660a69c 100644
--- a/src/test/ui/enum-discriminant/discriminant_value.rs
+++ b/src/test/ui/enum-discriminant/discriminant_value.rs
@@ -1,6 +1,6 @@
 // run-pass
 #![allow(stable_features)]
-#![feature(arbitrary_enum_discriminant, core, core_intrinsics)]
+#![feature(core, core_intrinsics)]
 
 extern crate core;
 use core::intrinsics::discriminant_value;
diff --git a/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.rs b/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.rs
deleted file mode 100644
index 3e90af4d36af3..0000000000000
--- a/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.rs
+++ /dev/null
@@ -1,10 +0,0 @@
-#![crate_type="lib"]
-
-enum Enum {
-  Unit = 1,
-  //~^ ERROR custom discriminant values are not allowed in enums with tuple or struct variants
-  Tuple() = 2,
-  //~^ ERROR discriminants on non-unit variants are experimental
-  Struct{} = 3,
-  //~^ ERROR discriminants on non-unit variants are experimental
-}
diff --git a/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.stderr b/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.stderr
deleted file mode 100644
index b5f61e6e991d8..0000000000000
--- a/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.stderr
+++ /dev/null
@@ -1,36 +0,0 @@
-error[E0658]: discriminants on non-unit variants are experimental
-  --> $DIR/feature-gate-arbitrary_enum_discriminant.rs:6:13
-   |
-LL |   Tuple() = 2,
-   |             ^
-   |
-   = note: see issue #60553 <https://github.com/rust-lang/rust/issues/60553> for more information
-   = help: add `#![feature(arbitrary_enum_discriminant)]` to the crate attributes to enable
-
-error[E0658]: discriminants on non-unit variants are experimental
-  --> $DIR/feature-gate-arbitrary_enum_discriminant.rs:8:14
-   |
-LL |   Struct{} = 3,
-   |              ^
-   |
-   = note: see issue #60553 <https://github.com/rust-lang/rust/issues/60553> for more information
-   = help: add `#![feature(arbitrary_enum_discriminant)]` to the crate attributes to enable
-
-error[E0658]: custom discriminant values are not allowed in enums with tuple or struct variants
-  --> $DIR/feature-gate-arbitrary_enum_discriminant.rs:4:10
-   |
-LL |   Unit = 1,
-   |          ^ disallowed custom discriminant
-LL |
-LL |   Tuple() = 2,
-   |   ----------- tuple variant defined here
-LL |
-LL |   Struct{} = 3,
-   |   ------------ struct variant defined here
-   |
-   = note: see issue #60553 <https://github.com/rust-lang/rust/issues/60553> for more information
-   = help: add `#![feature(arbitrary_enum_discriminant)]` to the crate attributes to enable
-
-error: aborting due to 3 previous errors
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/enum-discriminant/issue-70453-generics-in-discr-ice-2.rs b/src/test/ui/enum-discriminant/issue-70453-generics-in-discr-ice-2.rs
index f927dd189038a..ad9fcc25b4127 100644
--- a/src/test/ui/enum-discriminant/issue-70453-generics-in-discr-ice-2.rs
+++ b/src/test/ui/enum-discriminant/issue-70453-generics-in-discr-ice-2.rs
@@ -1,4 +1,4 @@
-#![feature(arbitrary_enum_discriminant, core_intrinsics)]
+#![feature(core_intrinsics)]
 
 extern crate core;
 use core::intrinsics::discriminant_value;
diff --git a/src/test/ui/enum-discriminant/issue-70453-polymorphic-ctfe.rs b/src/test/ui/enum-discriminant/issue-70453-polymorphic-ctfe.rs
index e62582fb5161a..42a062239d34a 100644
--- a/src/test/ui/enum-discriminant/issue-70453-polymorphic-ctfe.rs
+++ b/src/test/ui/enum-discriminant/issue-70453-polymorphic-ctfe.rs
@@ -1,4 +1,4 @@
-#![feature(arbitrary_enum_discriminant, core_intrinsics)]
+#![feature(core_intrinsics)]
 
 extern crate core;
 use core::intrinsics::discriminant_value;
diff --git a/src/test/ui/enum-discriminant/issue-70509-partial_eq.rs b/src/test/ui/enum-discriminant/issue-70509-partial_eq.rs
index ae389e1146645..3adac7b72621c 100644
--- a/src/test/ui/enum-discriminant/issue-70509-partial_eq.rs
+++ b/src/test/ui/enum-discriminant/issue-70509-partial_eq.rs
@@ -1,5 +1,5 @@
 // run-pass
-#![feature(repr128, arbitrary_enum_discriminant)]
+#![feature(repr128)]
 //~^ WARN the feature `repr128` is incomplete
 
 #[derive(PartialEq, Debug)]
diff --git a/src/test/ui/enum-discriminant/issue-70509-partial_eq.stderr b/src/test/ui/enum-discriminant/issue-70509-partial_eq.stderr
index 5bf6ea56ebc77..04fb13f37a006 100644
--- a/src/test/ui/enum-discriminant/issue-70509-partial_eq.stderr
+++ b/src/test/ui/enum-discriminant/issue-70509-partial_eq.stderr
@@ -1,7 +1,7 @@
 warning: the feature `repr128` is incomplete and may not be safe to use and/or cause compiler crashes
   --> $DIR/issue-70509-partial_eq.rs:2:12
    |
-LL | #![feature(repr128, arbitrary_enum_discriminant)]
+LL | #![feature(repr128)]
    |            ^^^^^^^
    |
    = note: `#[warn(incomplete_features)]` on by default
diff --git a/src/test/ui/intrinsics/panic-uninitialized-zeroed.rs b/src/test/ui/intrinsics/panic-uninitialized-zeroed.rs
index 72c0d7913e525..88ef8182f0238 100644
--- a/src/test/ui/intrinsics/panic-uninitialized-zeroed.rs
+++ b/src/test/ui/intrinsics/panic-uninitialized-zeroed.rs
@@ -5,7 +5,7 @@
 
 // This test checks panic emitted from `mem::{uninitialized,zeroed}`.
 
-#![feature(never_type, arbitrary_enum_discriminant)]
+#![feature(never_type)]
 #![allow(deprecated, invalid_value)]
 
 use std::{
diff --git a/src/test/ui/parser/issue-17383.rs b/src/test/ui/parser/issue-17383.rs
deleted file mode 100644
index 7bf0e64f2c0a3..0000000000000
--- a/src/test/ui/parser/issue-17383.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-enum X {
-    A = 3,
-    //~^ ERROR custom discriminant values are not allowed in enums with tuple or struct variants
-    B(usize)
-}
-
-fn main() {}
diff --git a/src/test/ui/parser/issue-17383.stderr b/src/test/ui/parser/issue-17383.stderr
deleted file mode 100644
index 265d6e1486614..0000000000000
--- a/src/test/ui/parser/issue-17383.stderr
+++ /dev/null
@@ -1,15 +0,0 @@
-error[E0658]: custom discriminant values are not allowed in enums with tuple or struct variants
-  --> $DIR/issue-17383.rs:2:9
-   |
-LL |     A = 3,
-   |         ^ disallowed custom discriminant
-LL |
-LL |     B(usize)
-   |     -------- tuple variant defined here
-   |
-   = note: see issue #60553 <https://github.com/rust-lang/rust/issues/60553> for more information
-   = help: add `#![feature(arbitrary_enum_discriminant)]` to the crate attributes to enable
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/parser/tag-variant-disr-non-nullary.rs b/src/test/ui/parser/tag-variant-disr-non-nullary.rs
deleted file mode 100644
index a9cfdd549c752..0000000000000
--- a/src/test/ui/parser/tag-variant-disr-non-nullary.rs
+++ /dev/null
@@ -1,12 +0,0 @@
-enum Color {
-    Red = 0xff0000,
-    //~^ ERROR custom discriminant values are not allowed in enums with tuple or struct variants
-    Green = 0x00ff00,
-    Blue = 0x0000ff,
-    Black = 0x000000,
-    White = 0xffffff,
-    Other(usize),
-    Other2(usize, usize),
-}
-
-fn main() {}
diff --git a/src/test/ui/parser/tag-variant-disr-non-nullary.stderr b/src/test/ui/parser/tag-variant-disr-non-nullary.stderr
deleted file mode 100644
index 79f044a0675b7..0000000000000
--- a/src/test/ui/parser/tag-variant-disr-non-nullary.stderr
+++ /dev/null
@@ -1,25 +0,0 @@
-error[E0658]: custom discriminant values are not allowed in enums with tuple or struct variants
-  --> $DIR/tag-variant-disr-non-nullary.rs:2:11
-   |
-LL |     Red = 0xff0000,
-   |           ^^^^^^^^ disallowed custom discriminant
-LL |
-LL |     Green = 0x00ff00,
-   |             ^^^^^^^^ disallowed custom discriminant
-LL |     Blue = 0x0000ff,
-   |            ^^^^^^^^ disallowed custom discriminant
-LL |     Black = 0x000000,
-   |             ^^^^^^^^ disallowed custom discriminant
-LL |     White = 0xffffff,
-   |             ^^^^^^^^ disallowed custom discriminant
-LL |     Other(usize),
-   |     ------------ tuple variant defined here
-LL |     Other2(usize, usize),
-   |     -------------------- tuple variant defined here
-   |
-   = note: see issue #60553 <https://github.com/rust-lang/rust/issues/60553> for more information
-   = help: add `#![feature(arbitrary_enum_discriminant)]` to the crate attributes to enable
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0658`.