Make ' a forbidden follower for the RawLifetimeOrLabel rule

This mirrors the changes from
rust-lang/rust#132341
which have been backported to appear in Rust 1.83

Author: mattheww

src/lexlucid/pretokenisation/pretokenisation_rules.rs

@@ -224,9 +224,9 @@ fn make_named_rules() -> BTreeMap<RuleName, Rule> {
                 )
             "##)),
 
-       // Lifetime or label
+       // Raw lifetime or label
        (RuleName::RawLifetimeOrLabel2021,
-        Rule::new_regex(
+        Rule::new_regex_with_forbidden_follower(
             |cp| PretokenData::RawLifetimeOrLabel {
                 name: cp["name"].into(),
             }, r##"\A
@@ -235,7 +235,8 @@ fn make_named_rules() -> BTreeMap<RuleName, Rule> {
                   [ \p{XID_Start} _ ]
                   \p{XID_Continue} *
                 )
-            "##)),
+            "##,
+            |c| c == '\'')),
 
        // Reserved lifetime or label prefix
        (RuleName::ReservedLifetimeOrLabelPrefix2021,

writeup/rationale.md

@@ -31,6 +31,7 @@ rather than trying to write non-overlapping lexer rules as the Reference does.
 The model described in this document uses one-character lookahead (beyond the token which will be matched) in the prelexing step, in two cases:
 
 - the lifetime-or-label rule, to prevent `'ab'c'` being analysed as `'ab` followed by `'c`
+  (and similarly for the raw-lifetime-or-label rule)
 - the rule for float literals ending in `.`, to make sure that `1.a` is analysed as `1` `.` `a` rather than `1.` `a`
 
 I think some kind of lookahead is unavoidable in these cases.

writeup/rules.md

@@ -219,6 +219,10 @@ when `character_sequence` represents an iterator over the sequence of characters
 )
 ```
 
+Forbidden followers:
+
+- The character <b>'</b>
+
 ##### Pretoken kind
 `RawLifetimeOrLabel`