[gcc/devel/rust/master] Fix parsing grammer of grouped expressions as the block tail expression

[Thomas Schwinge <tschwinge@gcc.gnu.org>]

https://gcc.gnu.org/g:fb1b2a6bf5eed9dd9405dca9b9c895f48509875e

commit fb1b2a6bf5eed9dd9405dca9b9c895f48509875e
Author: Philip Herron <philip.herron@embecosm.com>
Date:   Tue Jul 19 10:49:37 2022 +0100

    Fix parsing grammer of grouped expressions as the block tail expression
    
    When we want to compile a grouped expression we had a check for the
    LEFT_PAREN during the parse_expr_without_block but this can't be handled
    here since in this paticular example the grouped expressions is simply the
    lhs of the bit shift expression. This is already handled as part of
    parse_expr so we can simply remove the rule here and rely on parse_expr
    handling this.
    
    Fixes #1393

Diff:
---
 gcc/rust/parse/rust-parse-impl.h         |  6 ------
 gcc/testsuite/rust/compile/issue-1393.rs | 13 +++++++++++++
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/gcc/rust/parse/rust-parse-impl.h b/gcc/rust/parse/rust-parse-impl.h
index 227564cb65a..d925aca05e9 100644
--- a/gcc/rust/parse/rust-parse-impl.h
+++ b/gcc/rust/parse/rust-parse-impl.h
@@ -7276,12 +7276,6 @@ Parser<ManagedTokenSource>::parse_expr_without_block (
     case LEFT_SQUARE:
       // array expr (creation, not index)
       return parse_array_expr (std::move (outer_attrs));
-    case LEFT_PAREN:
-      /* either grouped expr or tuple expr - depends on whether there is a
-       * comma
-       * inside the parentheses - if so, tuple expr, otherwise, grouped expr.
-       */
-      return parse_grouped_or_tuple_expr (std::move (outer_attrs));
       default: {
 	/* HACK: piggyback on pratt parsed expr and abuse polymorphism to
 	 * essentially downcast */
diff --git a/gcc/testsuite/rust/compile/issue-1393.rs b/gcc/testsuite/rust/compile/issue-1393.rs
new file mode 100644
index 00000000000..e09f01b62e5
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-1393.rs
@@ -0,0 +1,13 @@
+fn tst() {
+    let a = 123;
+    let b = 0;
+    let _c = if b == 0 {
+        (a & 0x7fffff) << 1
+    } else {
+        (a & 0x7fffff) | 0x800000
+    };
+}
+
+fn main() {
+    tst()
+}