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_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 {