[committed 21/88] gccrs: fixed compiler error message on wildcard pattern within expression

[arthur . cohen]

From: Abdul Rafey <abdulraf...@gmail.com>

gcc/rust/ChangeLog:

        * parse/rust-parse-impl.h (Parser::null_denotation): Add proper error
        when seeing wildcard var on right side of assignment.

gcc/testsuite/ChangeLog:

        * rust/compile/issue-867.rs: New test.

Signed-off-by: Abdul Rafey <abdulraf...@gmail.com>
---
 gcc/rust/parse/rust-parse-impl.h        | 6 ++++++
 gcc/testsuite/rust/compile/issue-867.rs | 8 ++++++++
 2 files changed, 14 insertions(+)
 create mode 100644 gcc/testsuite/rust/compile/issue-867.rs

diff --git a/gcc/rust/parse/rust-parse-impl.h b/gcc/rust/parse/rust-parse-impl.h
index d71bafded63..af749ca9200 100644
--- a/gcc/rust/parse/rust-parse-impl.h
+++ b/gcc/rust/parse/rust-parse-impl.h
@@ -13021,6 +13021,12 @@ Parser<ManagedTokenSource>::null_denotation 
(const_TokenPtr tok,
     case UNSAFE:
       return parse_unsafe_block_expr (std::move (outer_attrs),
                                      tok->get_locus ());
+    case UNDERSCORE:
+      add_error (
+       Error (tok->get_locus (),
+              "use of %qs is not allowed on the right-side of an assignment",
+              tok->get_token_description ()));
+      return nullptr;
     default:
       if (!restrictions.expr_can_be_null)
        add_error (Error (tok->get_locus (),
diff --git a/gcc/testsuite/rust/compile/issue-867.rs 
b/gcc/testsuite/rust/compile/issue-867.rs
new file mode 100644
index 00000000000..8e120685c1a
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-867.rs
@@ -0,0 +1,8 @@
+fn main() {
+    let _ = 42;
+    let a = _ + 123; // { dg-error "use of '_' is not allowed on the 
right-side of an assignment" }
+                     // { dg-error {failed to parse expression in let 
statement} "" { target *-*-* } .-1  }
+                     // { dg-error {failed to parse statement or expression 
without block in block expression} "" { target *-*-* } .-2 }
+                     // { dg-error {unrecognised token '\}' for start of item} 
"" { target *-*-* } .+2 }
+                     // { dg-error {failed to parse item in crate} "" { target 
*-*-* } .+1 }
+}
-- 
2.40.0