Merge #1044

1044: Restrict follow-up tokens on `expr` and `stmt` r=CohenArthur a=CohenArthur

This adds a base for respecting the [Macro Follow-Set Ambiguity specification](https://doc.rust-lang.org/reference/macro-ambiguity.html).

If the design is validated, adding more restrictions on other fragment specifiers should not be difficult

Addresses #947 

Co-authored-by: Arthur Cohen <arthur.cohen@embecosm.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/gcc/rust/parse/rust-parse.h b/gcc/rust/parse/rust-parse.h
index 9a31fb6..c86d194 100644
--- a/gcc/rust/parse/rust-parse.h
+++ b/gcc/rust/parse/rust-parse.h
@@ -702,6 +702,18 @@ private:
 std::string
 extract_module_path (const AST::AttrVec &inner_attrs,
 		     const AST::AttrVec &outer_attrs, const std::string &name);
+
+/**
+ * Check if a MacroMatch is allowed to follow the last parsed MacroMatch.
+ *
+ * @param last_match Last matcher parsed before the current match
+ * @param match Current matcher to check
+ *
+ * @return true if the follow-up is valid, false otherwise
+ */
+bool
+is_match_compatible (AST::MacroMatch &last_match,
+		     AST::MacroMatch &current_match);
 } // namespace Rust
 
 // as now template, include implementations of all methods