Rollup merge of #126452 - compiler-errors:raw-lifetimes, r=spastorino

Implement raw lifetimes and labels (`'r#ident`)

This PR does two things:
1. Reserve lifetime prefixes, e.g. `'prefix#lt` in edition 2021.
2. Implements raw lifetimes, e.g. `'r#async` in edition 2021.

This PR additionally extends the `keyword_idents_2024` lint to also check lifetimes.

cc `@traviscross`
r? parser

compiler/rustc_ast/src/mut_visit.rs

@@ -752,7 +752,7 @@ fn visit_lazy_tts<T: MutVisitor>(vis: &mut T, lazy_tts: &mut Option<LazyAttrToke
 pub fn visit_token<T: MutVisitor>(vis: &mut T, t: &mut Token) {
     let Token { kind, span } = t;
     match kind {
-        token::Ident(name, _ /*raw*/) | token::Lifetime(name) => {
+        token::Ident(name, _is_raw) | token::Lifetime(name, _is_raw) => {
             let mut ident = Ident::new(*name, *span);
             vis.visit_ident(&mut ident);
             *name = ident.name;
@@ -762,7 +762,7 @@ pub fn visit_token<T: MutVisitor>(vis: &mut T, t: &mut Token) {
         token::NtIdent(ident, _is_raw) => {
             vis.visit_ident(ident);
         }
-        token::NtLifetime(ident) => {
+        token::NtLifetime(ident, _is_raw) => {
             vis.visit_ident(ident);
         }
         token::Interpolated(nt) => {

compiler/rustc_ast/src/token.rs

@@ -331,11 +331,11 @@ pub enum TokenKind {
     /// Do not forget about `NtLifetime` when you want to match on lifetime identifiers.
     /// It's recommended to use `Token::(lifetime,uninterpolate,uninterpolated_span)` to
     /// treat regular and interpolated lifetime identifiers in the same way.
-    Lifetime(Symbol),
+    Lifetime(Symbol, IdentIsRaw),
     /// This identifier (and its span) is the lifetime passed to the
     /// declarative macro. The span in the surrounding `Token` is the span of
     /// the `lifetime` metavariable in the macro's RHS.
-    NtLifetime(Ident),
+    NtLifetime(Ident, IdentIsRaw),
 
     /// An embedded AST node, as produced by a macro. This only exists for
     /// historical reasons. We'd like to get rid of it, for multiple reasons.
@@ -458,7 +458,7 @@ impl Token {
     /// if they keep spans or perform edition checks.
     pub fn uninterpolated_span(&self) -> Span {
         match self.kind {
-            NtIdent(ident, _) | NtLifetime(ident) => ident.span,
+            NtIdent(ident, _) | NtLifetime(ident, _) => ident.span,
             Interpolated(ref nt) => nt.use_span(),
             _ => self.span,
         }
@@ -661,7 +661,9 @@ impl Token {
     pub fn uninterpolate(&self) -> Cow<'_, Token> {
         match self.kind {
             NtIdent(ident, is_raw) => Cow::Owned(Token::new(Ident(ident.name, is_raw), ident.span)),
-            NtLifetime(ident) => Cow::Owned(Token::new(Lifetime(ident.name), ident.span)),
+            NtLifetime(ident, is_raw) => {
+                Cow::Owned(Token::new(Lifetime(ident.name, is_raw), ident.span))
+            }
             _ => Cow::Borrowed(self),
         }
     }
@@ -679,11 +681,11 @@ impl Token {
 
     /// Returns a lifetime identifier if this token is a lifetime.
     #[inline]
-    pub fn lifetime(&self) -> Option<Ident> {
+    pub fn lifetime(&self) -> Option<(Ident, IdentIsRaw)> {
         // We avoid using `Token::uninterpolate` here because it's slow.
         match self.kind {
-            Lifetime(name) => Some(Ident::new(name, self.span)),
+            Lifetime(name, is_raw) => Some((Ident::new(name, self.span), is_raw)),
-            NtLifetime(ident) => Some(ident),
+            NtLifetime(ident, is_raw) => Some((ident, is_raw)),
             _ => None,
         }
     }
@@ -865,7 +867,7 @@ impl Token {
                 _ => return None,
             },
             SingleQuote => match joint.kind {
-                Ident(name, IdentIsRaw::No) => Lifetime(Symbol::intern(&format!("'{name}"))),
+                Ident(name, is_raw) => Lifetime(Symbol::intern(&format!("'{name}")), is_raw),
                 _ => return None,
             },
 

compiler/rustc_ast/src/tokenstream.rs

@@ -482,11 +482,11 @@ impl TokenStream {
             token::NtIdent(ident, is_raw) => {
                 TokenTree::Token(Token::new(token::Ident(ident.name, is_raw), ident.span), spacing)
             }
-            token::NtLifetime(ident) => TokenTree::Delimited(
+            token::NtLifetime(ident, is_raw) => TokenTree::Delimited(
                 DelimSpan::from_single(token.span),
                 DelimSpacing::new(Spacing::JointHidden, spacing),
                 Delimiter::Invisible,
-                TokenStream::token_alone(token::Lifetime(ident.name), ident.span),
+                TokenStream::token_alone(token::Lifetime(ident.name, is_raw), ident.span),
             ),
             token::Interpolated(ref nt) => TokenTree::Delimited(
                 DelimSpan::from_single(token.span),

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -11,7 +11,9 @@ use std::borrow::Cow;
 use ast::TraitBoundModifiers;
 use rustc_ast::attr::AttrIdGenerator;
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, BinOpToken, CommentKind, Delimiter, Nonterminal, Token, TokenKind};
+use rustc_ast::token::{
+    self, BinOpToken, CommentKind, Delimiter, IdentIsRaw, Nonterminal, Token, TokenKind,
+};
 use rustc_ast::tokenstream::{Spacing, TokenStream, TokenTree};
 use rustc_ast::util::classify;
 use rustc_ast::util::comments::{Comment, CommentStyle};
@@ -947,8 +949,13 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
             token::NtIdent(ident, is_raw) => {
                 IdentPrinter::for_ast_ident(ident, is_raw.into()).to_string().into()
             }
-            token::Lifetime(name) => name.to_string().into(),
+
-            token::NtLifetime(ident) => ident.name.to_string().into(),
+            token::Lifetime(name, IdentIsRaw::No)
+            | token::NtLifetime(Ident { name, .. }, IdentIsRaw::No) => name.to_string().into(),
+            token::Lifetime(name, IdentIsRaw::Yes)
+            | token::NtLifetime(Ident { name, .. }, IdentIsRaw::Yes) => {
+                format!("'r#{}", &name.as_str()[1..]).into()
+            }
 
             /* Other */
             token::DocComment(comment_kind, attr_style, data) => {

compiler/rustc_expand/src/mbe/macro_parser.rs

@@ -398,8 +398,10 @@ pub(crate) enum NamedMatch {
 fn token_name_eq(t1: &Token, t2: &Token) -> bool {
     if let (Some((ident1, is_raw1)), Some((ident2, is_raw2))) = (t1.ident(), t2.ident()) {
         ident1.name == ident2.name && is_raw1 == is_raw2
-    } else if let (Some(ident1), Some(ident2)) = (t1.lifetime(), t2.lifetime()) {
+    } else if let (Some((ident1, is_raw1)), Some((ident2, is_raw2))) =
-        ident1.name == ident2.name
+        (t1.lifetime(), t2.lifetime())
+    {
+        ident1.name == ident2.name && is_raw1 == is_raw2
     } else {
         t1.kind == t2.kind
     }

compiler/rustc_expand/src/mbe/transcribe.rs

@@ -283,9 +283,9 @@ pub(super) fn transcribe<'a>(
                             let kind = token::NtIdent(*ident, *is_raw);
                             TokenTree::token_alone(kind, sp)
                         }
-                        MatchedSingle(ParseNtResult::Lifetime(ident)) => {
+                        MatchedSingle(ParseNtResult::Lifetime(ident, is_raw)) => {
                             marker.visit_span(&mut sp);
-                            let kind = token::NtLifetime(*ident);
+                            let kind = token::NtLifetime(*ident, *is_raw);
                             TokenTree::token_alone(kind, sp)
                         }
                         MatchedSingle(ParseNtResult::Nt(nt)) => {

compiler/rustc_expand/src/proc_macro_server.rs

@@ -229,15 +229,16 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
                     span: ident.span,
                 })),
 
-                Lifetime(name) => {
+                Lifetime(name, is_raw) => {
                     let ident = symbol::Ident::new(name, span).without_first_quote();
                     trees.extend([
                         TokenTree::Punct(Punct { ch: b'\'', joint: true, span }),
-                        TokenTree::Ident(Ident { sym: ident.name, is_raw: false, span }),
+                        TokenTree::Ident(Ident { sym: ident.name, is_raw: is_raw.into(), span }),
                     ]);
                 }
-                NtLifetime(ident) => {
+                NtLifetime(ident, is_raw) => {
-                    let stream = TokenStream::token_alone(token::Lifetime(ident.name), ident.span);
+                    let stream =
+                        TokenStream::token_alone(token::Lifetime(ident.name, is_raw), ident.span);
                     trees.push(TokenTree::Group(Group {
                         delimiter: pm::Delimiter::None,
                         stream: Some(stream),

compiler/rustc_lexer/src/lib.rs

@@ -91,6 +91,15 @@ pub enum TokenKind {
     /// tokens.
     UnknownPrefix,
 
+    /// An unknown prefix in a lifetime, like `'foo#`.
+    ///
+    /// Note that like above, only the `'` and prefix are included in the token
+    /// and not the separator.
+    UnknownPrefixLifetime,
+
+    /// `'r#lt`, which in edition < 2021 is split into several tokens: `'r # lt`.
+    RawLifetime,
+
     /// Similar to the above, but *always* an error on every edition. This is used
     /// for emoji identifier recovery, as those are not meant to be ever accepted.
     InvalidPrefix,
@@ -677,9 +686,17 @@ impl Cursor<'_> {
             return Literal { kind, suffix_start };
         }
 
+        if self.first() == 'r' && self.second() == '#' && is_id_start(self.third()) {
+            // Eat "r" and `#`, and identifier start characters.
+            self.bump();
+            self.bump();
+            self.bump();
+            self.eat_while(is_id_continue);
+            return RawLifetime;
+        }
+
         // Either a lifetime or a character literal with
         // length greater than 1.
-
         let starts_with_number = self.first().is_ascii_digit();
 
         // Skip the literal contents.
@@ -688,15 +705,17 @@ impl Cursor<'_> {
         self.bump();
         self.eat_while(is_id_continue);
 
-        // Check if after skipping literal contents we've met a closing
+        match self.first() {
-        // single quote (which means that user attempted to create a
+            // Check if after skipping literal contents we've met a closing
-        // string with single quotes).
+            // single quote (which means that user attempted to create a
-        if self.first() == '\'' {
+            // string with single quotes).
-            self.bump();
+            '\'' => {
-            let kind = Char { terminated: true };
+                self.bump();
-            Literal { kind, suffix_start: self.pos_within_token() }
+                let kind = Char { terminated: true };
-        } else {
+                Literal { kind, suffix_start: self.pos_within_token() }
-            Lifetime { starts_with_number }
+            }
+            '#' if !starts_with_number => UnknownPrefixLifetime,
+            _ => Lifetime { starts_with_number },
         }
     }
 

compiler/rustc_lint/messages.ftl

@@ -708,6 +708,10 @@ lint_range_endpoint_out_of_range = range endpoint is out of range for `{$ty}`
 lint_range_use_inclusive_range = use an inclusive range instead
 
 
+lint_raw_prefix = prefix `'r` is reserved
+    .label = reserved prefix
+    .suggestion = insert whitespace here to avoid this being parsed as a prefix in Rust 2021
+
 lint_reason_must_be_string_literal = reason must be a string literal
 
 lint_reason_must_come_last = reason in lint attribute must come last

compiler/rustc_lint/src/builtin.rs

@@ -1851,9 +1851,16 @@ impl KeywordIdents {
                 TokenTree::Token(token, _) => {
                     if let Some((ident, token::IdentIsRaw::No)) = token.ident() {
                         if !prev_dollar {
-                            self.check_ident_token(cx, UnderMacro(true), ident);
+                            self.check_ident_token(cx, UnderMacro(true), ident, "");
                         }
-                    } else if *token == TokenKind::Dollar {
+                    } else if let Some((ident, token::IdentIsRaw::No)) = token.lifetime() {
+                        self.check_ident_token(
+                            cx,
+                            UnderMacro(true),
+                            ident.without_first_quote(),
+                            "'",
+                        );
+                    } else if token.kind == TokenKind::Dollar {
                         prev_dollar = true;
                         continue;
                     }
@@ -1869,6 +1876,7 @@ impl KeywordIdents {
         cx: &EarlyContext<'_>,
         UnderMacro(under_macro): UnderMacro,
         ident: Ident,
+        prefix: &'static str,
     ) {
         let (lint, edition) = match ident.name {
             kw::Async | kw::Await | kw::Try => (KEYWORD_IDENTS_2018, Edition::Edition2018),
@@ -1902,7 +1910,7 @@ impl KeywordIdents {
         cx.emit_span_lint(
             lint,
             ident.span,
-            BuiltinKeywordIdents { kw: ident, next: edition, suggestion: ident.span },
+            BuiltinKeywordIdents { kw: ident, next: edition, suggestion: ident.span, prefix },
         );
     }
 }
@@ -1915,7 +1923,11 @@ impl EarlyLintPass for KeywordIdents {
         self.check_tokens(cx, &mac.args.tokens);
     }
     fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: Ident) {
-        self.check_ident_token(cx, UnderMacro(false), ident);
+        if ident.name.as_str().starts_with('\'') {
+            self.check_ident_token(cx, UnderMacro(false), ident.without_first_quote(), "'");
+        } else {
+            self.check_ident_token(cx, UnderMacro(false), ident, "");
+        }
     }
 }
 

compiler/rustc_lint/src/context/diagnostics.rs

@@ -172,6 +172,10 @@ pub(super) fn decorate_lint(sess: &Session, diagnostic: BuiltinLintDiag, diag: &
             }
             .decorate_lint(diag);
         }
+        BuiltinLintDiag::RawPrefix(label_span) => {
+            lints::RawPrefix { label: label_span, suggestion: label_span.shrink_to_hi() }
+                .decorate_lint(diag);
+        }
         BuiltinLintDiag::UnusedBuiltinAttribute { attr_name, macro_name, invoc_span } => {
             lints::UnusedBuiltinAttribute { invoc_span, attr_name, macro_name }.decorate_lint(diag);
         }

compiler/rustc_lint/src/lints.rs

@@ -363,8 +363,9 @@ pub(crate) enum BuiltinEllipsisInclusiveRangePatternsLint {
 pub(crate) struct BuiltinKeywordIdents {
     pub kw: Ident,
     pub next: Edition,
-    #[suggestion(code = "r#{kw}", applicability = "machine-applicable")]
+    #[suggestion(code = "{prefix}r#{kw}", applicability = "machine-applicable")]
     pub suggestion: Span,
+    pub prefix: &'static str,
 }
 
 #[derive(LintDiagnostic)]
@@ -2814,6 +2815,15 @@ pub(crate) struct ReservedPrefix {
     pub prefix: String,
 }
 
+#[derive(LintDiagnostic)]
+#[diag(lint_raw_prefix)]
+pub(crate) struct RawPrefix {
+    #[label]
+    pub label: Span,
+    #[suggestion(code = " ", applicability = "machine-applicable")]
+    pub suggestion: Span,
+}
+
 #[derive(LintDiagnostic)]
 #[diag(lint_unused_builtin_attribute)]
 pub(crate) struct UnusedBuiltinAttribute {

compiler/rustc_lint_defs/src/lib.rs

@@ -612,6 +612,8 @@ pub enum BuiltinLintDiag {
     LegacyDeriveHelpers(Span),
     OrPatternsBackCompat(Span, String),
     ReservedPrefix(Span, String),
+    /// `'r#` in edition < 2021.
+    RawPrefix(Span),
     TrailingMacro(bool, Ident),
     BreakWithLabelAndLoop(Span),
     UnicodeTextFlow(Span, String),

compiler/rustc_parse/src/lexer/mod.rs

@@ -13,7 +13,6 @@ use rustc_session::lint::builtin::{
 };
 use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::parse::ParseSess;
-use rustc_span::edition::Edition;
 use rustc_span::symbol::Symbol;
 use rustc_span::{BytePos, Pos, Span};
 use tracing::debug;
@@ -188,9 +187,7 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
                     preceded_by_whitespace = true;
                     continue;
                 }
-                rustc_lexer::TokenKind::Ident => {
+                rustc_lexer::TokenKind::Ident => self.ident(start),
-                    self.ident(start)
-                }
                 rustc_lexer::TokenKind::RawIdent => {
                     let sym = nfc_normalize(self.str_from(start + BytePos(2)));
                     let span = self.mk_sp(start, self.pos);
@@ -205,20 +202,31 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
                     self.report_unknown_prefix(start);
                     self.ident(start)
                 }
-                rustc_lexer::TokenKind::InvalidIdent
+                rustc_lexer::TokenKind::UnknownPrefixLifetime => {
-                | rustc_lexer::TokenKind::InvalidPrefix
+                    self.report_unknown_prefix(start);
+                    // Include the leading `'` in the real identifier, for macro
+                    // expansion purposes. See #12512 for the gory details of why
+                    // this is necessary.
+                    let lifetime_name = self.str_from(start);
+                    self.last_lifetime = Some(self.mk_sp(start, start + BytePos(1)));
+                    let ident = Symbol::intern(lifetime_name);
+                    token::Lifetime(ident, IdentIsRaw::No)
+                }
+                rustc_lexer::TokenKind::InvalidIdent | rustc_lexer::TokenKind::InvalidPrefix
                     // Do not recover an identifier with emoji if the codepoint is a confusable
                     // with a recoverable substitution token, like `➖`.
-                    if !UNICODE_ARRAY
+                    if !UNICODE_ARRAY.iter().any(|&(c, _, _)| {
-                        .iter()
+                        let sym = self.str_from(start);
-                        .any(|&(c, _, _)| {
+                        sym.chars().count() == 1 && c == sym.chars().next().unwrap()
-                            let sym = self.str_from(start);
+                    }) =>
-                            sym.chars().count() == 1 && c == sym.chars().next().unwrap()
-                        }) =>
                 {
                     let sym = nfc_normalize(self.str_from(start));
                     let span = self.mk_sp(start, self.pos);
-                    self.psess.bad_unicode_identifiers.borrow_mut().entry(sym).or_default()
+                    self.psess
+                        .bad_unicode_identifiers
+                        .borrow_mut()
+                        .entry(sym)
+                        .or_default()
                         .push(span);
                     token::Ident(sym, IdentIsRaw::No)
                 }
@@ -249,9 +257,9 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
                     let suffix = if suffix_start < self.pos {
                         let string = self.str_from(suffix_start);
                         if string == "_" {
-                            self
+                            self.dcx().emit_err(errors::UnderscoreLiteralSuffix {
-                                .dcx()
+                                span: self.mk_sp(suffix_start, self.pos),
-                                .emit_err(errors::UnderscoreLiteralSuffix { span: self.mk_sp(suffix_start, self.pos) });
+                            });
                             None
                         } else {
                             Some(Symbol::intern(string))
@@ -269,12 +277,47 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
                     self.last_lifetime = Some(self.mk_sp(start, start + BytePos(1)));
                     if starts_with_number {
                         let span = self.mk_sp(start, self.pos);
-                        self.dcx().struct_err("lifetimes cannot start with a number")
+                        self.dcx()
+                            .struct_err("lifetimes cannot start with a number")
                             .with_span(span)
                             .stash(span, StashKey::LifetimeIsChar);
                     }
                     let ident = Symbol::intern(lifetime_name);
-                    token::Lifetime(ident)
+                    token::Lifetime(ident, IdentIsRaw::No)
+                }
+                rustc_lexer::TokenKind::RawLifetime => {
+                    self.last_lifetime = Some(self.mk_sp(start, start + BytePos(1)));
+
+                    let ident_start = start + BytePos(3);
+                    let prefix_span = self.mk_sp(start, ident_start);
+
+                    if prefix_span.at_least_rust_2021() {
+                        let lifetime_name_without_tick = self.str_from(ident_start);
+                        // Put the `'` back onto the lifetime name.
+                        let mut lifetime_name = String::with_capacity(lifetime_name_without_tick.len() + 1);
+                        lifetime_name.push('\'');
+                        lifetime_name += lifetime_name_without_tick;
+                        let sym = Symbol::intern(&lifetime_name);
+
+                        token::Lifetime(sym, IdentIsRaw::Yes)
+                    } else {
+                        // Otherwise, this should be parsed like `'r`. Warn about it though.
+                        self.psess.buffer_lint(
+                            RUST_2021_PREFIXES_INCOMPATIBLE_SYNTAX,
+                            prefix_span,
+                            ast::CRATE_NODE_ID,
+                            BuiltinLintDiag::RawPrefix(prefix_span),
+                        );
+
+                        // Reset the state so we just lex the `'r`.
+                        let lt_start = start + BytePos(2);
+                        self.pos = lt_start;
+                        self.cursor = Cursor::new(&str_before[2 as usize..]);
+
+                        let lifetime_name = self.str_from(start);
+                        let ident = Symbol::intern(lifetime_name);
+                        token::Lifetime(ident, IdentIsRaw::No)
+                    }
                 }
                 rustc_lexer::TokenKind::Semi => token::Semi,
                 rustc_lexer::TokenKind::Comma => token::Comma,
@@ -331,16 +374,19 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
                     // first remove compound tokens like `<<` from `rustc_lexer`, and then add
                     // fancier error recovery to it, as there will be less overall work to do this
                     // way.
-                    let (token, sugg) = unicode_chars::check_for_substitution(self, start, c, repeats+1);
+                    let (token, sugg) =
+                        unicode_chars::check_for_substitution(self, start, c, repeats + 1);
                     self.dcx().emit_err(errors::UnknownTokenStart {
                         span: self.mk_sp(start, self.pos + Pos::from_usize(repeats * c.len_utf8())),
                         escaped: escaped_char(c),
                         sugg,
-                        null: if c == '\x00' {Some(errors::UnknownTokenNull)} else {None},
+                        null: if c == '\x00' { Some(errors::UnknownTokenNull) } else { None },
                         repeat: if repeats > 0 {
                             swallow_next_invalid = repeats;
                             Some(errors::UnknownTokenRepeat { repeats })
-                        } else {None}
+                        } else {
+                            None
+                        },
                     });
 
                     if let Some(token) = token {
@@ -699,7 +745,7 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
 
         let expn_data = prefix_span.ctxt().outer_expn_data();
 
-        if expn_data.edition >= Edition::Edition2021 {
+        if expn_data.edition.at_least_rust_2021() {
             // In Rust 2021, this is a hard error.
             let sugg = if prefix == "rb" {
                 Some(errors::UnknownPrefixSugg::UseBr(prefix_span))

compiler/rustc_parse/src/parser/expr.rs

@@ -2050,7 +2050,7 @@ impl<'a> Parser<'a> {
         };
         // On an error path, eagerly consider a lifetime to be an unclosed character lit, if that
         // makes sense.
-        if let Some(ident) = self.token.lifetime()
+        if let Some((ident, IdentIsRaw::No)) = self.token.lifetime()
             && could_be_unclosed_char_literal(ident)
         {
             let lt = self.expect_lifetime();
@@ -2925,9 +2925,9 @@ impl<'a> Parser<'a> {
     }
 
     pub(crate) fn eat_label(&mut self) -> Option<Label> {
-        if let Some(ident) = self.token.lifetime() {
+        if let Some((ident, is_raw)) = self.token.lifetime() {
             // Disallow `'fn`, but with a better error message than `expect_lifetime`.
-            if ident.without_first_quote().is_reserved() {
+            if matches!(is_raw, IdentIsRaw::No) && ident.without_first_quote().is_reserved() {
                 self.dcx().emit_err(errors::InvalidLabel { span: ident.span, name: ident.name });
             }
 

compiler/rustc_parse/src/parser/mod.rs

@@ -1666,7 +1666,7 @@ enum FlatToken {
 pub enum ParseNtResult {
     Tt(TokenTree),
     Ident(Ident, IdentIsRaw),
-    Lifetime(Ident),
+    Lifetime(Ident, IdentIsRaw),
 
     /// This case will eventually be removed, along with `Token::Interpolate`.
     Nt(Lrc<Nonterminal>),

compiler/rustc_parse/src/parser/nonterminal.rs

@@ -88,7 +88,7 @@ impl<'a> Parser<'a> {
             },
             NonterminalKind::Pat(pat_kind) => token.can_begin_pattern(pat_kind),
             NonterminalKind::Lifetime => match &token.kind {
-                token::Lifetime(_) | token::NtLifetime(..) => true,
+                token::Lifetime(..) | token::NtLifetime(..) => true,
                 _ => false,
             },
             NonterminalKind::TT | NonterminalKind::Item | NonterminalKind::Stmt => {
@@ -171,9 +171,9 @@ impl<'a> Parser<'a> {
             NonterminalKind::Lifetime => {
                 // We want to keep `'keyword` parsing, just like `keyword` is still
                 // an ident for nonterminal purposes.
-                return if let Some(ident) = self.token.lifetime() {
+                return if let Some((ident, is_raw)) = self.token.lifetime() {
                     self.bump();
-                    Ok(ParseNtResult::Lifetime(ident))
+                    Ok(ParseNtResult::Lifetime(ident, is_raw))
                 } else {
                     Err(self.dcx().create_err(UnexpectedNonterminal::Lifetime {
                         span: self.token.span,

compiler/rustc_parse/src/parser/pat.rs

@@ -1,6 +1,6 @@
 use rustc_ast::mut_visit::{walk_pat, MutVisitor};
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, BinOpToken, Delimiter, Token};
+use rustc_ast::token::{self, BinOpToken, Delimiter, IdentIsRaw, Token};
 use rustc_ast::{
     self as ast, AttrVec, BindingMode, ByRef, Expr, ExprKind, MacCall, Mutability, Pat, PatField,
     PatFieldsRest, PatKind, Path, QSelf, RangeEnd, RangeSyntax,
@@ -548,7 +548,7 @@ impl<'a> Parser<'a> {
                     None => PatKind::Path(qself, path),
                 }
             }
-        } else if let Some(lt) = self.token.lifetime()
+        } else if let Some((lt, IdentIsRaw::No)) = self.token.lifetime()
             // In pattern position, we're totally fine with using "next token isn't colon"
             // as a heuristic. We could probably just always try to recover if it's a lifetime,
             // because we never have `'a: label {}` in a pattern position anyways, but it does
@@ -689,7 +689,7 @@ impl<'a> Parser<'a> {
     /// Parse `&pat` / `&mut pat`.
     fn parse_pat_deref(&mut self, expected: Option<Expected>) -> PResult<'a, PatKind> {
         self.expect_and()?;
-        if let Some(lifetime) = self.token.lifetime() {
+        if let Some((lifetime, _)) = self.token.lifetime() {
             self.bump(); // `'a`
 
             self.dcx().emit_err(UnexpectedLifetimeInPattern {

compiler/rustc_parse/src/parser/ty.rs

@@ -1,5 +1,5 @@
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, BinOpToken, Delimiter, Token, TokenKind};
+use rustc_ast::token::{self, BinOpToken, Delimiter, IdentIsRaw, Token, TokenKind};
 use rustc_ast::util::case::Case;
 use rustc_ast::{
     self as ast, BareFnTy, BoundAsyncness, BoundConstness, BoundPolarity, FnRetTy, GenericBound,
@@ -1285,8 +1285,9 @@ impl<'a> Parser<'a> {
 
     /// Parses a single lifetime `'a` or panics.
     pub(super) fn expect_lifetime(&mut self) -> Lifetime {
-        if let Some(ident) = self.token.lifetime() {
+        if let Some((ident, is_raw)) = self.token.lifetime() {
-            if ident.without_first_quote().is_reserved()
+            if matches!(is_raw, IdentIsRaw::No)
+                && ident.without_first_quote().is_reserved()
                 && ![kw::UnderscoreLifetime, kw::StaticLifetime].contains(&ident.name)
             {
                 self.dcx().emit_err(errors::KeywordLifetime { span: ident.span });

src/librustdoc/html/highlight.rs

@@ -879,7 +879,9 @@ impl<'src> Classifier<'src> {
             | TokenKind::UnknownPrefix
             | TokenKind::InvalidPrefix
             | TokenKind::InvalidIdent => Class::Ident(self.new_span(before, text)),
-            TokenKind::Lifetime { .. } => Class::Lifetime,
+            TokenKind::Lifetime { .. }
+            | TokenKind::RawLifetime
+            | TokenKind::UnknownPrefixLifetime => Class::Lifetime,
             TokenKind::Eof => panic!("Eof in advance"),
         };
         // Anything that didn't return above is the simple case where we the

src/tools/rust-analyzer/crates/parser/src/lexed_str.rs

@@ -198,6 +198,13 @@ impl<'a> Converter<'a> {
                     }
                     LIFETIME_IDENT
                 }
+                rustc_lexer::TokenKind::UnknownPrefixLifetime => {
+                    err = "Unknown lifetime prefix";
+                    LIFETIME_IDENT
+                }
+                rustc_lexer::TokenKind::RawLifetime => {
+                    LIFETIME_IDENT
+                }
 
                 rustc_lexer::TokenKind::Semi => T![;],
                 rustc_lexer::TokenKind::Comma => T![,],

src/tools/rustfmt/src/expr.rs

@@ -462,7 +462,7 @@ fn rewrite_empty_block(
         return None;
     }
 
-    let label_str = rewrite_label(label);
+    let label_str = rewrite_label(context, label);
     if attrs.map_or(false, |a| !inner_attributes(a).is_empty()) {
         return None;
     }
@@ -527,7 +527,7 @@ fn rewrite_single_line_block(
     if let Some(block_expr) = stmt::Stmt::from_simple_block(context, block, attrs) {
         let expr_shape = shape.offset_left(last_line_width(prefix))?;
         let expr_str = block_expr.rewrite(context, expr_shape)?;
-        let label_str = rewrite_label(label);
+        let label_str = rewrite_label(context, label);
         let result = format!("{prefix}{label_str}{{ {expr_str} }}");
         if result.len() <= shape.width && !result.contains('\n') {
             return Some(result);
@@ -562,7 +562,7 @@ pub(crate) fn rewrite_block_with_visitor(
     }
 
     let inner_attrs = attrs.map(inner_attributes);
-    let label_str = rewrite_label(label);
+    let label_str = rewrite_label(context, label);
     visitor.visit_block(block, inner_attrs.as_deref(), has_braces);
     let visitor_context = visitor.get_context();
     context
@@ -939,7 +939,7 @@ impl<'a> ControlFlow<'a> {
             fresh_shape
         };
 
-        let label_string = rewrite_label(self.label);
+        let label_string = rewrite_label(context, self.label);
         // 1 = space after keyword.
         let offset = self.keyword.len() + label_string.len() + 1;
 
@@ -1168,9 +1168,9 @@ impl<'a> Rewrite for ControlFlow<'a> {
     }
 }
 
-fn rewrite_label(opt_label: Option<ast::Label>) -> Cow<'static, str> {
+fn rewrite_label(context: &RewriteContext<'_>, opt_label: Option<ast::Label>) -> Cow<'static, str> {
     match opt_label {
-        Some(label) => Cow::from(format!("{}: ", label.ident)),
+        Some(label) => Cow::from(format!("{}: ", context.snippet(label.ident.span))),
         None => Cow::from(""),
     }
 }

src/tools/rustfmt/src/macros.rs

@@ -1074,7 +1074,7 @@ fn force_space_before(tok: &TokenKind) -> bool {
 fn ident_like(tok: &Token) -> bool {
     matches!(
         tok.kind,
-        TokenKind::Ident(..) | TokenKind::Literal(..) | TokenKind::Lifetime(_)
+        TokenKind::Ident(..) | TokenKind::Literal(..) | TokenKind::Lifetime(..)
     )
 }
 
@@ -1099,7 +1099,9 @@ fn next_space(tok: &TokenKind) -> SpaceState {
         | TokenKind::OpenDelim(_)
         | TokenKind::CloseDelim(_) => SpaceState::Never,
 
-        TokenKind::Literal(..) | TokenKind::Ident(..) | TokenKind::Lifetime(_) => SpaceState::Ident,
+        TokenKind::Literal(..) | TokenKind::Ident(..) | TokenKind::Lifetime(..) => {
+            SpaceState::Ident
+        }
 
         _ => SpaceState::Always,
     }

src/tools/rustfmt/src/types.rs

@@ -548,7 +548,7 @@ impl Rewrite for ast::AnonConst {
 
 impl Rewrite for ast::Lifetime {
     fn rewrite(&self, context: &RewriteContext<'_>, _: Shape) -> Option<String> {
-        Some(rewrite_ident(context, self.ident).to_owned())
+        Some(context.snippet(self.ident.span).to_owned())
     }
 }
 

src/tools/rustfmt/tests/target/raw-lifetimes.rs

@@ -0,0 +1,15 @@
+// rustfmt-edition: 2021
+
+// Simple idempotence test for raw lifetimes.
+
+fn test<'r#gen>() -> &'r#gen () {
+    // Test raw lifetimes...
+}
+
+fn label() {
+    'r#label: {
+        // Test raw labels.
+    }
+}
+
+fn main() {}

tests/ui/lexer/prefixed-lifetime.rs

@@ -0,0 +1,10 @@
+//@ edition: 2021
+
+macro_rules! w {
+    ($($tt:tt)*) => {};
+}
+
+w!('foo#lifetime);
+//~^ ERROR prefix `'foo` is unknown
+
+fn main() {}

tests/ui/lexer/prefixed-lifetime.stderr

@@ -0,0 +1,14 @@
+error: prefix `'foo` is unknown
+  --> $DIR/prefixed-lifetime.rs:7:4
+   |
+LL | w!('foo#lifetime);
+   |    ^^^^ unknown prefix
+   |
+   = note: prefixed identifiers and literals are reserved since Rust 2021
+help: consider inserting whitespace here
+   |
+LL | w!('foo #lifetime);
+   |        +
+
+error: aborting due to 1 previous error
+

tests/ui/lifetimes/raw/gen-lt.e2024.stderr

@@ -0,0 +1,8 @@
+error: lifetimes cannot use keyword names
+  --> $DIR/gen-lt.rs:11:11
+   |
+LL | fn gen_lt<'gen>() {}
+   |           ^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/lifetimes/raw/gen-lt.rs

@@ -0,0 +1,14 @@
+//@ revisions: e2021 e2024
+
+//@[e2021] edition:2021
+//@[e2024] edition:2024
+//@[e2024] compile-flags: -Zunstable-options
+
+//@[e2021] check-pass
+
+fn raw_gen_lt<'r#gen>() {}
+
+fn gen_lt<'gen>() {}
+//[e2024]~^ ERROR lifetimes cannot use keyword names
+
+fn main() {}

tests/ui/lifetimes/raw/lifetimes-eq.rs

@@ -0,0 +1,8 @@
+//@ edition: 2021
+//@ check-pass
+
+// Test that `'r#a` is `'a`.
+
+fn test<'r#a>(x: &'a ()) {}
+
+fn main() {}

tests/ui/lifetimes/raw/macro-lt.rs

@@ -0,0 +1,12 @@
+//@ check-pass
+//@ edition: 2021
+
+macro_rules! lifetime {
+    ($lt:lifetime) => {
+        fn hello<$lt>() {}
+    }
+}
+
+lifetime!('r#struct);
+
+fn main() {}

tests/ui/lifetimes/raw/multiple-prefixes.rs

@@ -0,0 +1,6 @@
+//@ edition: 2021
+
+fn test(x: &'r#r#r ()) {}
+//~^ ERROR expected type, found `#`
+
+fn main() {}

tests/ui/lifetimes/raw/multiple-prefixes.stderr

@@ -0,0 +1,8 @@
+error: expected type, found `#`
+  --> $DIR/multiple-prefixes.rs:3:17
+   |
+LL | fn test(x: &'r#r#r ()) {}
+   |                 ^ expected type
+
+error: aborting due to 1 previous error
+

tests/ui/lifetimes/raw/prim-lt.rs

@@ -0,0 +1,8 @@
+//@ check-pass
+//@ edition: 2021
+
+// Checks a primitive name can be defined as a lifetime.
+
+fn foo<'r#i32>() {}
+
+fn main() {}

tests/ui/lifetimes/raw/simple.rs

@@ -0,0 +1,21 @@
+//@ check-pass
+//@ edition: 2021
+
+fn foo<'r#struct>() {}
+
+fn hr<T>() where for<'r#struct> T: Into<&'r#struct ()> {}
+
+trait Foo<'r#struct> {}
+
+trait Bar<'r#struct> {
+    fn method(&'r#struct self) {}
+    fn method2(self: &'r#struct Self) {}
+}
+
+fn labeled() {
+    'r#struct: loop {
+        break 'r#struct;
+    }
+}
+
+fn main() {}

tests/ui/lifetimes/raw/static-lt.rs

@@ -0,0 +1,8 @@
+//@ check-pass
+//@ edition: 2021
+
+// Makes sure that `'r#static` is `'static`
+
+const FOO: &'r#static str = "hello, world";
+
+fn main() {}

tests/ui/lifetimes/raw/three-tokens.rs

@@ -0,0 +1,12 @@
+//@ edition: 2015
+//@ check-pass
+// Ensure that we parse `'r#lt` as three tokens in edition 2015.
+
+macro_rules! ed2015 {
+    ('r # lt) => {};
+    ($lt:lifetime) => { compile_error!() };
+}
+
+ed2015!('r#lt);
+
+fn main() {}

tests/ui/rust-2024/gen-kw.e2015.stderr

@@ -31,5 +31,14 @@ LL |     () => { mod test { fn gen() {} } }
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2024!
    = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
 
-error: aborting due to 3 previous errors
+error: `gen` is a keyword in the 2024 edition
+  --> $DIR/gen-kw.rs:25:9
+   |
+LL | fn test<'gen>() {}
+   |         ^^^^ help: you can use a raw identifier to stay compatible: `'r#gen`
+   |
+   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2024!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: aborting due to 4 previous errors
 

tests/ui/rust-2024/gen-kw.e2018.stderr

@@ -31,5 +31,14 @@ LL |     () => { mod test { fn gen() {} } }
    = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2024!
    = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
 
-error: aborting due to 3 previous errors
+error: `gen` is a keyword in the 2024 edition
+  --> $DIR/gen-kw.rs:25:9
+   |
+LL | fn test<'gen>() {}
+   |         ^^^^ help: you can use a raw identifier to stay compatible: `'r#gen`
+   |
+   = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2024!
+   = note: for more information, see issue #49716 <https://github.com/rust-lang/rust/issues/49716>
+
+error: aborting due to 4 previous errors
 

tests/ui/rust-2024/gen-kw.rs

@@ -22,4 +22,9 @@ macro_rules! t {
     //[e2018]~| WARNING this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2024!
 }
 
+fn test<'gen>() {}
+//~^ ERROR `gen` is a keyword in the 2024 edition
+//[e2015]~| WARNING this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2024!
+//[e2018]~| WARNING this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2024!
+
 t!();