Rollup merge of rust-lang#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, rust-lang#102275 (comment).

The FCP was completed in rust-lang#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() {

src/test/ui/half-open-range-patterns/exclusive_range_pattern_syntax_collision.rs

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

src/test/ui/half-open-range-patterns/exclusive_range_pattern_syntax_collision2.rs

@@ -1,4 +1,3 @@
-#![feature(half_open_range_patterns)]
 #![feature(exclusive_range_pattern)]
 
 fn main() {

src/test/ui/half-open-range-patterns/exclusive_range_pattern_syntax_collision3.rs

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/exclusive_range_pattern_syntax_collision3.rs:6:12
+  --> $DIR/exclusive_range_pattern_syntax_collision3.rs:5:12
    |
 LL |     match [5..4, 99..105, 43..44] {
    |           ----------------------- this expression has type `[std::ops::Range<{integer}>; 3]`
@@ -10,7 +10,7 @@ LL |         [..9, 99..100, _] => {},
                 found type `{integer}`
 
 error[E0308]: mismatched types
-  --> $DIR/exclusive_range_pattern_syntax_collision3.rs:6:15
+  --> $DIR/exclusive_range_pattern_syntax_collision3.rs:5:15
    |
 LL |     match [5..4, 99..105, 43..44] {
    |           ----------------------- this expression has type `[std::ops::Range<{integer}>; 3]`
@@ -23,7 +23,7 @@ LL |         [..9, 99..100, _] => {},
                 found type `{integer}`
 
 error[E0308]: mismatched types
-  --> $DIR/exclusive_range_pattern_syntax_collision3.rs:6:19
+  --> $DIR/exclusive_range_pattern_syntax_collision3.rs:5:19
    |
 LL |     match [5..4, 99..105, 43..44] {
    |           ----------------------- this expression has type `[std::ops::Range<{integer}>; 3]`

src/test/ui/half-open-range-patterns/exclusive_range_pattern_syntax_collision3.stderr

@@ -0,0 +1,7 @@
+#![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;
+    //~^ `X..` patterns in slices are experimental
+}

src/test/ui/half-open-range-patterns/feature-gate-half-open-range-patterns-in-slices.rs

@@ -0,0 +1,12 @@
+error[E0658]: `X..` patterns in slices are experimental
+  --> $DIR/feature-gate-half-open-range-patterns-in-slices.rs:5:10
+   |
+LL |     let [a @ 3.., b @ ..3, c @ 4..6, ..] = xs;
+   |          ^^^^^^^
+   |
+   = note: see issue #67264 <https://github.com/rust-lang/rust/issues/67264> for more information
+   = help: add `#![feature(half_open_range_patterns_in_slices)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/half-open-range-patterns/feature-gate-half-open-range-patterns-in-slices.stderr

@@ -1,4 +1,3 @@
-#![feature(half_open_range_patterns)]
 #![feature(exclusive_range_pattern)]
 
 fn main() {

src/test/ui/half-open-range-patterns/feature-gate-half-open-range-patterns.rs

@@ -1,17 +1,17 @@
 error[E0029]: only `char` and numeric types are allowed in range patterns
-  --> $DIR/half-open-range-pats-bad-types.rs:5:9
+  --> $DIR/half-open-range-pats-bad-types.rs:4:9
    |
 LL |     let "a".. = "a";
    |         ^^^ this is of type `&'static str` but it should be `char` or numeric
 
 error[E0029]: only `char` and numeric types are allowed in range patterns
-  --> $DIR/half-open-range-pats-bad-types.rs:6:11
+  --> $DIR/half-open-range-pats-bad-types.rs:5:11
    |
 LL |     let .."a" = "a";
    |           ^^^ this is of type `&'static str` but it should be `char` or numeric
 
 error[E0029]: only `char` and numeric types are allowed in range patterns
-  --> $DIR/half-open-range-pats-bad-types.rs:7:12
+  --> $DIR/half-open-range-pats-bad-types.rs:6:12
    |
 LL |     let ..="a" = "a";
    |            ^^^ this is of type `&'static str` but it should be `char` or numeric

src/test/ui/half-open-range-patterns/feature-gate-half-open-range-patterns.stderr

@@ -1,6 +1,5 @@
 // Test various non-exhaustive matches for `X..`, `..=X` and `..X` ranges.
 
-#![feature(half_open_range_patterns)]
 #![feature(exclusive_range_pattern)]
 #![allow(illegal_floating_point_literal_pattern)]