Rollup merge of #132363 - compiler-errors:raw-lt-id-valid, r=wesleywiser

Enforce that raw lifetimes must be valid raw identifiers

Make sure that the identifier part of a raw lifetime is a valid raw identifier. This precludes `'r#_` and all module segment paths for now.

I don't believe this is compelling to support. This was raised by `@ehuss` in https://github.com/rust-lang/reference/pull/1603#discussion_r1822726753 (well, specifically the `'r#_` case), but I don't see why we shouldn't just make it consistent with raw identifiers.

3 files changed, 20 insertions, 4 deletions

diff --git a/compiler/rustc_parse/messages.ftl b/compiler/rustc_parse/messages.ftl
index 1af7fb9b86a..ef259703f0c 100644
--- a/compiler/rustc_parse/messages.ftl
+++ b/compiler/rustc_parse/messages.ftl
@@ -77,6 +77,8 @@ parse_box_syntax_removed_suggestion = use `Box::new()` instead
 
 parse_cannot_be_raw_ident = `{$ident}` cannot be a raw identifier
 
+parse_cannot_be_raw_lifetime = `{$ident}` cannot be a raw lifetime
+
 parse_catch_after_try = keyword `catch` cannot follow a `try` block
     .help = try using `match` on the result of the `try` block instead
 
diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs
index fdd500e90f8..7ec4ad6dc35 100644
--- a/compiler/rustc_parse/src/errors.rs
+++ b/compiler/rustc_parse/src/errors.rs
@@ -2019,6 +2019,14 @@ pub(crate) struct CannotBeRawIdent {
 }
 
 #[derive(Diagnostic)]
+#[diag(parse_cannot_be_raw_lifetime)]
+pub(crate) struct CannotBeRawLifetime {
+    #[primary_span]
+    pub span: Span,
+    pub ident: Symbol,
+}
+
+#[derive(Diagnostic)]
 #[diag(parse_keyword_lifetime)]
 pub(crate) struct KeywordLifetime {
     #[primary_span]
diff --git a/compiler/rustc_parse/src/lexer/mod.rs b/compiler/rustc_parse/src/lexer/mod.rs
index d627ef3d2cb..226de65445c 100644
--- a/compiler/rustc_parse/src/lexer/mod.rs
+++ b/compiler/rustc_parse/src/lexer/mod.rs
@@ -294,15 +294,21 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
                     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);
+                        let span = self.mk_sp(start, self.pos);
+
+                        let lifetime_name_without_tick = Symbol::intern(&self.str_from(ident_start));
+                        if !lifetime_name_without_tick.can_be_raw() {
+                            self.dcx().emit_err(errors::CannotBeRawLifetime { span, ident: lifetime_name_without_tick });
+                        }
+
                         // Put the `'` back onto the lifetime name.
-                        let mut lifetime_name = String::with_capacity(lifetime_name_without_tick.len() + 1);
+                        let mut lifetime_name = String::with_capacity(lifetime_name_without_tick.as_str().len() + 1);
                         lifetime_name.push('\'');
-                        lifetime_name += lifetime_name_without_tick;
+                        lifetime_name += lifetime_name_without_tick.as_str();
                         let sym = Symbol::intern(&lifetime_name);
 
                         // Make sure we mark this as a raw identifier.
-                        self.psess.raw_identifier_spans.push(self.mk_sp(start, self.pos));
+                        self.psess.raw_identifier_spans.push(span);
 
                         token::Lifetime(sym, IdentIsRaw::Yes)
                     } else {