Rollup merge of #102275 - Urgau:stabilize-half_open_range_patterns, r=cjgillot

Stabilize `half_open_range_patterns`

This PR stabilize `feature(half_open_range_patterns)`:
```
Allows using `..=X` as a pattern.
```

And adds a new `feature(half_open_range_patterns_in_slices)` for the slice part, #102275 (comment).

The FCP was completed in #67264.

Author: JohnTitor

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -461,7 +461,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                     if let PatKind::Range(Some(_), None, Spanned { .. }) = inner_pat.kind {
                         gate_feature_post!(
                             &self,
-                            half_open_range_patterns,
+                            half_open_range_patterns_in_slices,
                             pat.span,
                             "`X..` patterns in slices are experimental"
                         );
@@ -589,7 +589,10 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
     gate_all!(generators, "yield syntax is experimental");
     gate_all!(raw_ref_op, "raw address of syntax is experimental");
     gate_all!(const_trait_impl, "const trait impls are experimental");
-    gate_all!(half_open_range_patterns, "half-open range patterns are unstable");
+    gate_all!(
+        half_open_range_patterns_in_slices,
+        "half-open range patterns in slices are unstable"
+    );
     gate_all!(inline_const, "inline-const is experimental");
     gate_all!(inline_const_pat, "inline-const in pattern position is experimental");
     gate_all!(associated_const_equality, "associated const equality is incomplete");

compiler/rustc_feature/src/accepted.rs

@@ -169,6 +169,8 @@ declare_features! (
     (accepted, global_allocator, "1.28.0", Some(27389), None),
     // FIXME: explain `globs`.
     (accepted, globs, "1.0.0", None, None),
+    /// Allows using `..=X` as a pattern.
+    (accepted, half_open_range_patterns, "CURRENT_RUSTC_VERSION", Some(67264), None),
     /// Allows using the `u128` and `i128` types.
     (accepted, i128_type, "1.26.0", Some(35118), None),
     /// Allows the use of `if let` expressions.

compiler/rustc_feature/src/active.rs

@@ -414,6 +414,8 @@ declare_features! (
     (incomplete, generic_const_exprs, "1.56.0", Some(76560), None),
     /// Allows using `..X`, `..=X`, `...X`, and `X..` as a pattern.
     (active, half_open_range_patterns, "1.41.0", Some(67264), None),
+    /// Allows using `..=X` as a patterns in slices.
+    (active, half_open_range_patterns_in_slices, "CURRENT_RUSTC_VERSION", Some(67264), None),
     /// Allows `if let` guard in match arms.
     (active, if_let_guard, "1.47.0", Some(51114), None),
     /// Allows using imported `main` function

compiler/rustc_middle/src/lib.rs

@@ -44,7 +44,7 @@
 #![feature(type_alias_impl_trait)]
 #![feature(associated_type_bounds)]
 #![feature(rustc_attrs)]
-#![feature(half_open_range_patterns)]
+#![cfg_attr(bootstrap, feature(half_open_range_patterns))]
 #![feature(control_flow_enum)]
 #![feature(associated_type_defaults)]
 #![feature(trusted_step)]

compiler/rustc_parse/src/parser/pat.rs

@@ -777,7 +777,6 @@ impl<'a> Parser<'a> {
     /// expression syntax `...expr` for splatting in expressions.
     fn parse_pat_range_to(&mut self, mut re: Spanned<RangeEnd>) -> PResult<'a, PatKind> {
         let end = self.parse_pat_range_end()?;
-        self.sess.gated_spans.gate(sym::half_open_range_patterns, re.span.to(self.prev_token.span));
         if let RangeEnd::Included(ref mut syn @ RangeSyntax::DotDotDot) = &mut re.node {
             *syn = RangeSyntax::DotDotEq;
             self.struct_span_err(re.span, "range-to patterns with `...` are not allowed")

compiler/rustc_span/src/symbol.rs

@@ -785,6 +785,7 @@ symbols! {
         globs,
         gt,
         half_open_range_patterns,
+        half_open_range_patterns_in_slices,
         hash,
         hexagon_target_feature,
         hidden,

src/doc/unstable-book/src/language-features/half-open-range-patterns-in-slices.md

@@ -0,0 +1,30 @@
+# `half_open_range_patterns_in_slices`
+
+The tracking issue for this feature is: [#67264]
+It is part of the `exclusive_range_pattern` feature,
+tracked at [#37854].
+
+[#67264]: https://github.com/rust-lang/rust/issues/67264
+[#37854]: https://github.com/rust-lang/rust/issues/37854
+-----
+
+This feature allow using top-level half-open range patterns in slices.
+
+```rust
+#![feature(half_open_range_patterns_in_slices)]
+#![feature(exclusive_range_pattern)]
+
+fn main() {
+    let xs = [13, 1, 5, 2, 3, 1, 21, 8];
+    let [a @ 3.., b @ ..3, c @ 4..6, ..] = xs else { return; };
+}
+```
+
+Note that this feature is not required if the patterns are wrapped between parenthesis.
+
+```rust
+fn main() {
+    let xs = [13, 1];
+    let [(a @ 3..), c] = xs else { return; };
+}
+```

src/doc/unstable-book/src/language-features/half-open-range-patterns.md

@@ -1,7 +1,7 @@
 // compile-flags: -Zunleash-the-miri-inside-of-you
 // aux-build:static_cross_crate.rs
 // stderr-per-bitwidth
-#![feature(exclusive_range_pattern, half_open_range_patterns)]
+#![feature(exclusive_range_pattern, half_open_range_patterns_in_slices)]
 
 extern crate static_cross_crate;
 

src/test/ui/consts/miri_unleashed/const_refers_to_static_cross_crate.rs

@@ -1,4 +1,4 @@
-#![feature(half_open_range_patterns)]
+#![feature(half_open_range_patterns_in_slices)]
 #![feature(exclusive_range_pattern)]
 
 fn main() {