[gcc r14-7476] gccrs: parser: macro: reject separator in `?` repetition

[Arthur Cohen]

https://gcc.gnu.org/g:694063d84e47f57c99d4558e789932c31a7bf6dd

commit r14-7476-g694063d84e47f57c99d4558e789932c31a7bf6dd
Author: Sebastian Kirmayer <gnu@kirmayer.eu>
Date:   Wed Apr 5 06:09:11 2023 +0200

    gccrs: parser: macro: reject separator in `?` repetition
    
    A matcher like $(a),? is no longer accepted.
    
    Fixes #2092.
    
    gcc/rust/ChangeLog:
    
            * parse/rust-parse-impl.h
            (Parser<ManagedTokenSource>::parse_macro_match_repetition):
            reject separator in `?` repetition
    
    gcc/testsuite/ChangeLog:
    
            * rust/compile/macro-issue2092.rs: New test.
    
    Signed-off-by: Sebastian Kirmayer <gnu@kirmayer.eu>

Diff:
---
 gcc/rust/parse/rust-parse-impl.h              | 10 ++++++++++
 gcc/testsuite/rust/compile/macro-issue2092.rs |  4 ++++
 2 files changed, 14 insertions(+)

diff --git a/gcc/rust/parse/rust-parse-impl.h b/gcc/rust/parse/rust-parse-impl.h
index e636252c255..6d20f480bb7 100644
--- a/gcc/rust/parse/rust-parse-impl.h
+++ b/gcc/rust/parse/rust-parse-impl.h
@@ -2261,6 +2261,16 @@ Parser<ManagedTokenSource>::parse_macro_match_repetition ()
     case QUESTION_MARK:
       op = AST::MacroMatchRepetition::ZERO_OR_ONE;
       lexer.skip_token ();
+
+      if (separator != nullptr)
+	{
+	  add_error (
+	    Error (separator->get_locus (),
+		   "the %<?%> macro repetition operator does not take a "
+		   "separator"));
+	  separator = nullptr;
+	}
+
       break;
     default:
       add_error (
diff --git a/gcc/testsuite/rust/compile/macro-issue2092.rs b/gcc/testsuite/rust/compile/macro-issue2092.rs
new file mode 100644
index 00000000000..ec207430168
--- /dev/null
+++ b/gcc/testsuite/rust/compile/macro-issue2092.rs
@@ -0,0 +1,4 @@
+macro_rules! foo {
+    // { dg-error "does not take a separator" "#2092" { target *-*-*} .+1 }
+    ($(a),?) => {};
+}