gccrs: port over readonly_error from c-family for lvalue assignment checks

Fixes #2391

gcc/rust/ChangeLog:

	* Make-lang.in: fixup formatting
	* resolve/rust-ast-resolve-expr.cc (ResolveExpr::visit): remove old check
	* rust-session-manager.cc (Session::compile_crate): call new lint
	* resolve/rust-ast-verify-assignee.h: Removed.
	* checks/errors/rust-readonly-check.cc: New file.
	* checks/errors/rust-readonly-check.h: New file.

gcc/testsuite/ChangeLog:

	* rust/compile/wrong_lhs_assignment.rs: update error message
	* rust/compile/issue-2391.rs: New test.

Signed-off-by: Philip Herron <herron.philip@googlemail.com>

2 files changed, 0 insertions, 91 deletions

diff --git a/gcc/rust/resolve/rust-ast-resolve-expr.cc b/gcc/rust/resolve/rust-ast-resolve-expr.cc
index 4242c8b..92466ed 100644
--- a/gcc/rust/resolve/rust-ast-resolve-expr.cc
+++ b/gcc/rust/resolve/rust-ast-resolve-expr.cc
@@ -19,7 +19,6 @@
 #include "rust-ast-resolve-expr.h"
 #include "rust-ast-resolve-stmt.h"
 #include "rust-ast-resolve-struct-expr-field.h"
-#include "rust-ast-verify-assignee.h"
 #include "rust-ast-resolve-type.h"
 #include "rust-ast-resolve-pattern.h"
 #include "rust-ast-resolve-path.h"
@@ -101,9 +100,6 @@ ResolveExpr::visit (AST::AssignmentExpr &expr)
 {
   ResolveExpr::go (expr.get_left_expr ().get (), prefix, canonical_prefix);
   ResolveExpr::go (expr.get_right_expr ().get (), prefix, canonical_prefix);
-
-  // need to verify the assignee
-  VerifyAsignee::go (expr.get_left_expr ().get ());
 }
 
 /* The "break rust" Easter egg.
@@ -191,9 +187,6 @@ ResolveExpr::visit (AST::CompoundAssignmentExpr &expr)
 {
   ResolveExpr::go (expr.get_left_expr ().get (), prefix, canonical_prefix);
   ResolveExpr::go (expr.get_right_expr ().get (), prefix, canonical_prefix);
-
-  // need to verify the assignee
-  VerifyAsignee::go (expr.get_left_expr ().get ());
 }
 
 void
diff --git a/gcc/rust/resolve/rust-ast-verify-assignee.h b/gcc/rust/resolve/rust-ast-verify-assignee.h
deleted file mode 100644
index ffe7d3f..0000000
--- a/gcc/rust/resolve/rust-ast-verify-assignee.h
+++ /dev/null
@@ -1,84 +0,0 @@
-// Copyright (C) 2020-2023 Free Software Foundation, Inc.
-
-// This file is part of GCC.
-
-// GCC is free software; you can redistribute it and/or modify it under
-// the terms of the GNU General Public License as published by the Free
-// Software Foundation; either version 3, or (at your option) any later
-// version.
-
-// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
-// WARRANTY; without even the implied warranty of MERCHANTABILITY or
-// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-// for more details.
-
-// You should have received a copy of the GNU General Public License
-// along with GCC; see the file COPYING3.  If not see
-// <http://www.gnu.org/licenses/>.
-
-#ifndef RUST_AST_VERIFY_ASSIGNEE
-#define RUST_AST_VERIFY_ASSIGNEE
-
-#include "rust-ast-resolve-base.h"
-#include "rust-ast-full.h"
-
-namespace Rust {
-namespace Resolver {
-
-class VerifyAsignee : public ResolverBase
-{
-  using Rust::Resolver::ResolverBase::visit;
-
-public:
-  static bool go (AST::Expr *assignee)
-  {
-    VerifyAsignee checker;
-    assignee->accept_vis (checker);
-    if (!checker.ok)
-      rust_error_at (assignee->get_locus (), ErrorCode::E0070,
-		     "invalid left-hand side of assignment");
-    return checker.ok;
-  }
-
-  void visit (AST::ArrayIndexExpr &expr) override
-  {
-    expr.get_array_expr ()->accept_vis (*this);
-  }
-
-  void visit (AST::FieldAccessExpr &expr) override
-  {
-    expr.get_receiver_expr ()->accept_vis (*this);
-  }
-
-  void visit (AST::TupleIndexExpr &expr) override
-  {
-    expr.get_tuple_expr ()->accept_vis (*this);
-  }
-
-  void visit (AST::IdentifierExpr &expr) override
-  {
-    if (!resolver->get_name_scope ().lookup (
-	  CanonicalPath::new_seg (expr.get_node_id (), expr.as_string ()),
-	  &resolved_node))
-      return;
-
-    ok = true;
-  }
-
-  void visit (AST::DereferenceExpr &expr) override
-  {
-    expr.get_dereferenced_expr ()->accept_vis (*this);
-  }
-
-  void visit (AST::PathInExpression &) override { ok = true; }
-
-private:
-  VerifyAsignee () : ResolverBase (), ok (false) {}
-
-  bool ok;
-};
-
-} // namespace Resolver
-} // namespace Rust
-
-#endif // RUST_AST_VERIFY_ASSIGNEE