Stabilize expr_2021 fragment in all editions

Co-authored-by: Michael Goulet <michael@errs.io>
Co-authored-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>

compiler/rustc_expand/src/mbe/macro_check.rs

@@ -119,7 +119,7 @@
 use rustc_span::{ErrorGuaranteed, Span};
 use smallvec::SmallVec;
 
-use super::quoted::VALID_FRAGMENT_NAMES_MSG_2021;
+use super::quoted::VALID_FRAGMENT_NAMES_MSG;
 use crate::errors;
 use crate::mbe::{KleeneToken, TokenTree};
 
@@ -274,7 +274,7 @@ fn check_binders(
                     psess.dcx().emit_err(errors::MissingFragmentSpecifier {
                         span,
                         add_span: span.shrink_to_hi(),
-                        valid: VALID_FRAGMENT_NAMES_MSG_2021,
+                        valid: VALID_FRAGMENT_NAMES_MSG,
                     });
                 } else {
                     psess.buffer_lint(

compiler/rustc_expand/src/mbe/quoted.rs

@@ -1,4 +1,3 @@
-use rustc_ast::token::NtExprKind::*;
 use rustc_ast::token::{self, Delimiter, IdentIsRaw, NonterminalKind, Token};
 use rustc_ast::{NodeId, tokenstream};
 use rustc_ast_pretty::pprust;
@@ -13,12 +12,9 @@
 use crate::mbe::macro_parser::count_metavar_decls;
 use crate::mbe::{Delimited, KleeneOp, KleeneToken, MetaVarExpr, SequenceRepetition, TokenTree};
 
-const VALID_FRAGMENT_NAMES_MSG: &str = "valid fragment specifiers are \
+pub(crate) const VALID_FRAGMENT_NAMES_MSG: &str = "valid fragment specifiers are \
-    `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, \
+    `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, \
-    `item` and `vis`";
+    `meta`, `tt`, `item` and `vis`, along with `expr_2021` and `pat_param` for edition compatibility";
-pub(crate) const VALID_FRAGMENT_NAMES_MSG_2021: &str = "valid fragment specifiers are \
-    `ident`, `block`, `stmt`, `expr`, `expr_2021`, `pat`, `ty`, `lifetime`, `literal`, `path`, \
-    `meta`, `tt`, `item` and `vis`";
 
 /// Takes a `tokenstream::TokenStream` and returns a `Vec<self::TokenTree>`. Specifically, this
 /// takes a generic `TokenStream`, such as is used in the rest of the compiler, and returns a
@@ -92,39 +88,13 @@ pub(super) fn parse(
                                     };
                                     let kind = NonterminalKind::from_symbol(fragment.name, edition)
                                         .unwrap_or_else(|| {
-                                            let help = match fragment.name {
-                                                sym::expr_2021 => {
-                                                    format!(
-                                                        "fragment specifier `expr_2021` \
-                                                         requires Rust 2021 or later\n\
-                                                         {VALID_FRAGMENT_NAMES_MSG}"
-                                                    )
-                                                }
-                                                _ if edition().at_least_rust_2021()
-                                                    && features.expr_fragment_specifier_2024 =>
-                                                {
-                                                    VALID_FRAGMENT_NAMES_MSG_2021.into()
-                                                }
-                                                _ => VALID_FRAGMENT_NAMES_MSG.into(),
-                                            };
                                             sess.dcx().emit_err(errors::InvalidFragmentSpecifier {
                                                 span,
                                                 fragment,
-                                                help,
+                                                help: VALID_FRAGMENT_NAMES_MSG.into(),
                                             });
                                             NonterminalKind::Ident
                                         });
-                                    if kind == NonterminalKind::Expr(Expr2021 { inferred: false })
-                                        && !features.expr_fragment_specifier_2024
-                                    {
-                                        rustc_session::parse::feature_err(
-                                            sess,
-                                            sym::expr_fragment_specifier_2024,
-                                            span,
-                                            "fragment specifier `expr_2021` is unstable",
-                                        )
-                                        .emit();
-                                    }
                                     result.push(TokenTree::MetaVarDecl(span, ident, Some(kind)));
                                     continue;
                                 }

compiler/rustc_feature/src/accepted.rs

@@ -189,6 +189,8 @@ macro_rules! declare_features {
     (accepted, exhaustive_integer_patterns, "1.33.0", Some(50907)),
     /// Allows explicit generic arguments specification with `impl Trait` present.
     (accepted, explicit_generic_args_with_impl_trait, "1.63.0", Some(83701)),
+    /// Uses 2024 rules for matching `expr` fragments in macros. Also enables `expr_2021` fragment.
+    (accepted, expr_fragment_specifier_2024, "CURRENT_RUSTC_VERSION", Some(123742)),
     /// Allows arbitrary expressions in key-value attributes at parse time.
     (accepted, extended_key_value_attributes, "1.54.0", Some(78835)),
     /// Allows resolving absolute paths as paths from other crates.

compiler/rustc_feature/src/unstable.rs

@@ -450,8 +450,6 @@ pub fn internal(&self, feature: Symbol) -> bool {
     (unstable, exhaustive_patterns, "1.13.0", Some(51085)),
     /// Allows explicit tail calls via `become` expression.
     (incomplete, explicit_tail_calls, "1.72.0", Some(112788)),
-    /// Uses 2024 rules for matching `expr` fragments in macros. Also enables `expr_2021` fragment.
-    (incomplete, expr_fragment_specifier_2024, "1.80.0", Some(123742)),
     /// Allows using `efiapi`, `sysv64` and `win64` as calling convention
     /// for functions with varargs.
     (unstable, extended_varargs_abi_support, "1.65.0", Some(100189)),

tests/ui/lint/unused/unused-macro-with-bad-frag-spec.stderr

@@ -4,7 +4,7 @@ error: invalid fragment specifier `t_ty`
 LL |     ($wrong:t_ty) => ()
    |      ^^^^^^^^^^^
    |
-   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`
+   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`, along with `expr_2021` and `pat_param` for edition compatibility
 
 error: aborting due to 1 previous error
 

tests/ui/macros/expr_2021.rs

@@ -0,0 +1,14 @@
+//@ check-pass
+//@ edition: 2015
+
+// Ensures expr_2021 fragment specifier is accepted in old editions
+
+macro_rules! my_macro {
+    ($x:expr_2021) => {
+        println!("Hello, {}!", $x);
+    };
+}
+
+fn main() {
+    my_macro!("world");
+}

tests/ui/macros/expr_2021_cargo_fix_edition.fixed

@@ -1,8 +1,6 @@
 //@ run-rustfix
 //@ check-pass
 //@ compile-flags: --edition=2021
-#![allow(incomplete_features)]
-#![feature(expr_fragment_specifier_2024)]
 #![warn(edition_2024_expr_fragment_specifier)]
 
 macro_rules! m {

tests/ui/macros/expr_2021_cargo_fix_edition.rs

@@ -1,8 +1,6 @@
 //@ run-rustfix
 //@ check-pass
 //@ compile-flags: --edition=2021
-#![allow(incomplete_features)]
-#![feature(expr_fragment_specifier_2024)]
 #![warn(edition_2024_expr_fragment_specifier)]
 
 macro_rules! m {

tests/ui/macros/expr_2021_cargo_fix_edition.stderr

@@ -1,5 +1,5 @@
 warning: the `expr` fragment specifier will accept more expressions in the 2024 edition
-  --> $DIR/expr_2021_cargo_fix_edition.rs:9:9
+  --> $DIR/expr_2021_cargo_fix_edition.rs:7:9
    |
 LL |     ($e:expr) => {
    |         ^^^^
@@ -7,7 +7,7 @@ LL |     ($e:expr) => {
    = warning: this changes meaning in Rust 2024
    = note: for more information, see Migration Guide <https://doc.rust-lang.org/nightly/edition-guide/rust-2024/macro-fragment-specifiers.html>
 note: the lint level is defined here
-  --> $DIR/expr_2021_cargo_fix_edition.rs:6:9
+  --> $DIR/expr_2021_cargo_fix_edition.rs:4:9
    |
 LL | #![warn(edition_2024_expr_fragment_specifier)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -17,7 +17,7 @@ LL |     ($e:expr_2021) => {
    |         ~~~~~~~~~
 
 warning: the `expr` fragment specifier will accept more expressions in the 2024 edition
-  --> $DIR/expr_2021_cargo_fix_edition.rs:13:11
+  --> $DIR/expr_2021_cargo_fix_edition.rs:11:11
    |
 LL |     ($($i:expr)*) => { };
    |           ^^^^

tests/ui/macros/expr_2021_inline_const.edi2021.stderr

@@ -1,5 +1,5 @@
 error: no rules expected the token `const`
-  --> $DIR/expr_2021_inline_const.rs:26:12
+  --> $DIR/expr_2021_inline_const.rs:23:12
    |
 LL | macro_rules! m2021 {
    | ------------------ when calling this macro
@@ -8,13 +8,13 @@ LL |     m2021!(const { 1 });
    |            ^^^^^ no rules expected this token in macro call
    |
 note: while trying to match meta-variable `$e:expr_2021`
-  --> $DIR/expr_2021_inline_const.rs:10:6
+  --> $DIR/expr_2021_inline_const.rs:7:6
    |
 LL |     ($e:expr_2021) => {
    |      ^^^^^^^^^^^^
 
 error: no rules expected the token `const`
-  --> $DIR/expr_2021_inline_const.rs:27:12
+  --> $DIR/expr_2021_inline_const.rs:24:12
    |
 LL | macro_rules! m2024 {
    | ------------------ when calling this macro
@@ -23,7 +23,7 @@ LL |     m2024!(const { 1 });
    |            ^^^^^ no rules expected this token in macro call
    |
 note: while trying to match meta-variable `$e:expr`
-  --> $DIR/expr_2021_inline_const.rs:16:6
+  --> $DIR/expr_2021_inline_const.rs:13:6
    |
 LL |     ($e:expr) => {
    |      ^^^^^^^

tests/ui/macros/expr_2021_inline_const.edi2024.stderr

@@ -1,5 +1,5 @@
 error: no rules expected the token `const`
-  --> $DIR/expr_2021_inline_const.rs:26:12
+  --> $DIR/expr_2021_inline_const.rs:23:12
    |
 LL | macro_rules! m2021 {
    | ------------------ when calling this macro
@@ -8,7 +8,7 @@ LL |     m2021!(const { 1 });
    |            ^^^^^ no rules expected this token in macro call
    |
 note: while trying to match meta-variable `$e:expr_2021`
-  --> $DIR/expr_2021_inline_const.rs:10:6
+  --> $DIR/expr_2021_inline_const.rs:7:6
    |
 LL |     ($e:expr_2021) => {
    |      ^^^^^^^^^^^^

tests/ui/macros/expr_2021_inline_const.rs

@@ -3,9 +3,6 @@
 //@[edi2021]compile-flags: --edition=2021
 
 // This test ensures that the inline const match only on edition 2024
-#![feature(expr_fragment_specifier_2024)]
-#![allow(incomplete_features)]
-
 macro_rules! m2021 {
     ($e:expr_2021) => {
         $e

tests/ui/macros/expr_2024_underscore_expr.edi2021.stderr

@@ -1,5 +1,5 @@
 error: no rules expected the token `_`
-  --> $DIR/expr_2024_underscore_expr.rs:22:12
+  --> $DIR/expr_2024_underscore_expr.rs:19:12
    |
 LL | macro_rules! m2021 {
    | ------------------ when calling this macro
@@ -8,13 +8,13 @@ LL |     m2021!(_);
    |            ^ no rules expected this token in macro call
    |
 note: while trying to match meta-variable `$e:expr_2021`
-  --> $DIR/expr_2024_underscore_expr.rs:10:6
+  --> $DIR/expr_2024_underscore_expr.rs:7:6
    |
 LL |     ($e:expr_2021) => {
    |      ^^^^^^^^^^^^
 
 error: no rules expected the token `_`
-  --> $DIR/expr_2024_underscore_expr.rs:23:12
+  --> $DIR/expr_2024_underscore_expr.rs:20:12
    |
 LL | macro_rules! m2024 {
    | ------------------ when calling this macro
@@ -23,7 +23,7 @@ LL |     m2024!(_);
    |            ^ no rules expected this token in macro call
    |
 note: while trying to match meta-variable `$e:expr`
-  --> $DIR/expr_2024_underscore_expr.rs:16:6
+  --> $DIR/expr_2024_underscore_expr.rs:13:6
    |
 LL |     ($e:expr) => {
    |      ^^^^^^^

tests/ui/macros/expr_2024_underscore_expr.edi2024.stderr

@@ -1,5 +1,5 @@
 error: no rules expected the token `_`
-  --> $DIR/expr_2024_underscore_expr.rs:22:12
+  --> $DIR/expr_2024_underscore_expr.rs:19:12
    |
 LL | macro_rules! m2021 {
    | ------------------ when calling this macro
@@ -8,7 +8,7 @@ LL |     m2021!(_);
    |            ^ no rules expected this token in macro call
    |
 note: while trying to match meta-variable `$e:expr_2021`
-  --> $DIR/expr_2024_underscore_expr.rs:10:6
+  --> $DIR/expr_2024_underscore_expr.rs:7:6
    |
 LL |     ($e:expr_2021) => {
    |      ^^^^^^^^^^^^

tests/ui/macros/expr_2024_underscore_expr.rs

@@ -3,9 +3,6 @@
 //@[edi2021]compile-flags: --edition=2021
 // This test ensures that the `_` tok is considered an
 // expression on edition 2024.
-#![feature(expr_fragment_specifier_2024)]
-#![allow(incomplete_features)]
-
 macro_rules! m2021 {
     ($e:expr_2021) => {
         $e = 1;

tests/ui/macros/feature-gate-expr_fragment_specifier_2024.rs

@@ -1,11 +0,0 @@
-//@  compile-flags: --edition=2024 -Z unstable-options
-
-macro_rules! m {
-    ($e:expr_2021) => { //~ ERROR: fragment specifier `expr_2021` is unstable
-        $e
-    };
-}
-
-fn main() {
-    m!(());
-}

tests/ui/macros/feature-gate-expr_fragment_specifier_2024.stderr

@@ -1,13 +0,0 @@
-error[E0658]: fragment specifier `expr_2021` is unstable
-  --> $DIR/feature-gate-expr_fragment_specifier_2024.rs:4:6
-   |
-LL |     ($e:expr_2021) => {
-   |      ^^^^^^^^^^^^
-   |
-   = note: see issue #123742 <https://github.com/rust-lang/rust/issues/123742> for more information
-   = help: add `#![feature(expr_fragment_specifier_2024)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0658`.

tests/ui/macros/invalid-fragment-specifier.stderr

@@ -4,7 +4,7 @@ error: invalid fragment specifier `id`
 LL |     ($wrong:id) => {};
    |      ^^^^^^^^^
    |
-   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`
+   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`, along with `expr_2021` and `pat_param` for edition compatibility
 
 error: invalid fragment specifier `r#if`
   --> $DIR/invalid-fragment-specifier.rs:7:6
@@ -12,7 +12,7 @@ error: invalid fragment specifier `r#if`
 LL |     ($wrong:r#if) => {};
    |      ^^^^^^^^^^^
    |
-   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`
+   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`, along with `expr_2021` and `pat_param` for edition compatibility
 
 error: aborting due to 2 previous errors
 

tests/ui/macros/issue-21356.stderr

@@ -4,7 +4,7 @@ error: invalid fragment specifier `t_ty`
 LL | macro_rules! test { ($wrong:t_ty ..) => () }
    |                      ^^^^^^^^^^^
    |
-   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`
+   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`, along with `expr_2021` and `pat_param` for edition compatibility
 
 error: aborting due to 1 previous error
 

tests/ui/macros/macro-missing-fragment.e2024.stderr

@@ -5,7 +5,7 @@ LL |     ( $( any_token $field_rust_type )* ) => {};
    |                    ^^^^^^^^^^^^^^^^
    |
    = note: fragment specifiers must be specified in the 2024 edition
-   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `expr_2021`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`
+   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`, along with `expr_2021` and `pat_param` for edition compatibility
 help: try adding a specifier here
    |
 LL |     ( $( any_token $field_rust_type:spec )* ) => {};
@@ -18,7 +18,7 @@ LL |     ( $name ) => {};
    |       ^^^^^
    |
    = note: fragment specifiers must be specified in the 2024 edition
-   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `expr_2021`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`
+   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`, along with `expr_2021` and `pat_param` for edition compatibility
 help: try adding a specifier here
    |
 LL |     ( $name:spec ) => {};
@@ -31,7 +31,7 @@ LL |     ( $name ) => {};
    |       ^^^^^
    |
    = note: fragment specifiers must be specified in the 2024 edition
-   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `expr_2021`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`
+   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`, along with `expr_2021` and `pat_param` for edition compatibility
 help: try adding a specifier here
    |
 LL |     ( $name:spec ) => {};

tests/ui/macros/metavar_cross_edition_recursive_macros.rs

@@ -6,7 +6,6 @@
 // This test captures the behavior of macro-generating-macros with fragment
 // specifiers across edition boundaries.
 
-#![feature(expr_fragment_specifier_2024)]
 #![feature(macro_metavar_expr)]
 #![allow(incomplete_features)]