macros: Allow checking past zeroable matches for follow-set restrictions

When trying to figure out if a match can follow another, we must figure
out whether or not that match is in the follow-set of the other. If that
match is zeroable (i.e a repetition using the * or ? kleene operators),
then we must be able to check the match after them: should our current
match not be present, the match after must be part of the follow-set.
This commits allows us to performs such checks properly and to "look
past" zeroable matches. This is not done with any lookahead, simply by
keeping a list of pointers to possible previous matches and checking all
of them for ambiguities.

1 files changed, 2 insertions, 2 deletions

diff --git a/gcc/rust/parse/rust-parse.h b/gcc/rust/parse/rust-parse.h
index 88bd311..5653293 100644
--- a/gcc/rust/parse/rust-parse.h
+++ b/gcc/rust/parse/rust-parse.h
@@ -714,8 +714,8 @@ extract_module_path (const AST::AttrVec &inner_attrs,
  * @return true if the follow-up is valid, false otherwise
  */
 bool
-is_match_compatible (AST::MacroMatch &last_match,
-		     AST::MacroMatch &current_match);
+is_match_compatible (const AST::MacroMatch &last_match,
+		     const AST::MacroMatch &current_match);
 } // namespace Rust
 
 // as now template, include implementations of all methods