[gcc r13-5540] gccrs: parser: Parse RangeFullExpr without erroring out

[Arthur Cohen <cohenarthur@gcc.gnu.org>]

https://gcc.gnu.org/g:f7014b28b81f43f62086d75222a9cfe7ca562b27

commit r13-5540-gf7014b28b81f43f62086d75222a9cfe7ca562b27
Author: Arthur Cohen <arthur.cohen@embecosm.com>
Date:   Mon Aug 29 16:37:16 2022 +0200

    gccrs: parser: Parse RangeFullExpr without erroring out
    
    gcc/rust/ChangeLog:
    
            * parse/rust-parse-impl.h: Allow parsing full range expressions without
            erroring out.
    
    gcc/testsuite/ChangeLog:
    
            * rust/compile/parse_range.rs: New test.

Diff:
---
 gcc/rust/parse/rust-parse-impl.h          | 6 +++++-
 gcc/testsuite/rust/compile/parse_range.rs | 9 +++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/gcc/rust/parse/rust-parse-impl.h b/gcc/rust/parse/rust-parse-impl.h
index fe628647653..72207a1bc22 100644
--- a/gcc/rust/parse/rust-parse-impl.h
+++ b/gcc/rust/parse/rust-parse-impl.h
@@ -14112,9 +14112,13 @@ std::unique_ptr<AST::RangeExpr>
 Parser<ManagedTokenSource>::parse_nud_range_exclusive_expr (
   const_TokenPtr tok, AST::AttrVec outer_attrs ATTRIBUTE_UNUSED)
 {
+  auto restrictions = ParseRestrictions ();
+  restrictions.expr_can_be_null = true;
+
   // FIXME: this probably parses expressions accidently or whatever
   // try parsing RHS (as tok has already been consumed in parse_expression)
-  std::unique_ptr<AST::Expr> right = parse_expr (LBP_DOT_DOT, AST::AttrVec ());
+  std::unique_ptr<AST::Expr> right
+    = parse_expr (LBP_DOT_DOT, AST::AttrVec (), restrictions);
 
   Location locus = tok->get_locus ();
 
diff --git a/gcc/testsuite/rust/compile/parse_range.rs b/gcc/testsuite/rust/compile/parse_range.rs
new file mode 100644
index 00000000000..03469b1f8d5
--- /dev/null
+++ b/gcc/testsuite/rust/compile/parse_range.rs
@@ -0,0 +1,9 @@
+// { dg-additional-options "-fsyntax-only" }
+
+fn main() {
+    let a = [1, 2, 3, 4];
+    let _ = a[0..];
+    let _ = a[..3];
+    let _ = a[0..3];
+    let _ = a[..];
+}