add name resolution processing for discriminant values

gcc/rust/ChangeLog:

	* resolve/rust-ast-resolve-item.cc (ResolveItem::visit):
		add name resolution processing for discriminant values
	* resolve/rust-ast-resolve-stmt.h:
		add name resolution processing for discriminant values

gcc/testsuite/ChangeLog:

	* rust/compile/nr2/exclude: Exclude enum_discriminant2.rs due to ICE
	* rust/compile/enum_discriminant2.rs: New test.
	* rust/compile/enum_discriminant3.rs: New test.

Signed-off-by: Ryutaro Okada <[email protected]>

Author: sakupan102

gcc/rust/resolve/rust-ast-resolve-item.cc

@@ -356,6 +356,7 @@ ResolveItem::visit (AST::EnumItemDiscriminant &item)
   auto cpath = canonical_prefix.append (decl);
 
   mappings.insert_canonical_path (item.get_node_id (), cpath);
+  ResolveExpr::go (item.get_expr (), path, cpath);
 }
 
 void

gcc/rust/resolve/rust-ast-resolve-stmt.h

@@ -234,6 +234,7 @@ class ResolveStmt : public ResolverBase
 	redefined_error (r);
       });
 
+    ResolveExpr::go (item.get_expr (), path, cpath);
     // Done, no fields.
   }
 

gcc/testsuite/rust/compile/enum_discriminant2.rs

@@ -0,0 +1,7 @@
+fn main() {
+    let y = 3;
+    enum Foo {
+        Bar = y,
+        // { dg-error "cannot find value .y. in this scope" "" { target *-*-* } .-1 }
+    }
+}

gcc/testsuite/rust/compile/enum_discriminant3.rs

@@ -0,0 +1,8 @@
+const x: isize = 1;
+// { dg-warning "unused name" "" { target *-*-* } .-1 }
+
+fn main() {
+    enum Foo {
+        Bar = x,
+    }
+}

gcc/testsuite/rust/compile/nr2/exclude

@@ -29,4 +29,5 @@ torture/name_resolve1.rs
 issue-3568.rs
 issue-3663.rs
 issue-3671.rs
+enum_discriminant2.rs
 # please don't delete the trailing newline