RawLifetimeOrLabel reprocessing: reject some keywords

This mirrors the changes from
rust-lang/rust#132363
"Enforce that raw lifetimes must be valid raw identifiers"
which have been backported to appear in Rust 1.83

Author: mattheww

src/lexlucid/reprocessing.rs

@@ -161,9 +161,7 @@ pub fn reprocess(pretoken: &Pretoken) -> Result<FineToken, Error> {
         PretokenData::LifetimeOrLabel { name } => {
             FineTokenData::LifetimeOrLabel { name: name.clone() }
         }
-        PretokenData::RawLifetimeOrLabel { name } => {
-            FineTokenData::RawLifetimeOrLabel { name: name.clone() }
-        }
+        PretokenData::RawLifetimeOrLabel { name } => lex_raw_lifetime_or_label(name)?,
         PretokenData::SingleQuoteLiteral {
             prefix,
             literal_content,
@@ -280,6 +278,15 @@ fn lex_raw_identifier(identifier: &Charseq) -> Result<FineTokenData, Error> {
     })
 }
 
+/// Validates and interprets a `r#...` raw identifier.
+fn lex_raw_lifetime_or_label(name: &Charseq) -> Result<FineTokenData, Error> {
+    let s = name.to_string();
+    if s == "_" || s == "crate" || s == "self" || s == "super" || s == "Self" {
+        return Err(rejected("forbidden raw lifetime or label"));
+    }
+    Ok(FineTokenData::RawLifetimeOrLabel { name: name.clone() })
+}
+
 /// Validates and interprets a single-quoted (character or byte) literal.
 fn lex_single_quote_literal(
     prefix: &Charseq,

writeup/reprocessing_cases.md

@@ -169,7 +169,14 @@ A `LifetimeOrLabel` pretoken is always accepted.
 Fine-grained token kind produced:
 `RawLifetimeOrLabel`
 
-A `RawLifetimeOrLabel` pretoken is always accepted.
+The pretoken is rejected if (and only if) the <var>name</var> is one of the following sequences of characters:
+
+- <b>_</b>
+- <b>crate</b>
+- <b>self</b>
+- <b>super</b>
+- <b>Self</b>
+
 
 ##### Attributes
 <var>name</var>: copied