gccrs: feat: Made changes to ensure no wrong assignments are done.

gcc/rust/ChangeLog:

	* backend/rust-compile-base.cc (HIRCompileBase::lvalue_p): Created a function that
	checks the lvalue.
	* backend/rust-compile-base.h: Created the Signature for above function
	* backend/rust-compile-expr.cc (lvalue_p): Moved the function from here to
	rust-compile-base.
	(CompileExpr::visit): Made changes to ensure proper readability and checking for
	wrong assignments.

Author: sriganeshres

Diff for: gcc/rust/backend/rust-compile-base.cc

@@ -1015,5 +1015,51 @@ HIRCompileBase::unit_expression (location_t locus)
   return Backend::constructor_expression (unit_type, false, {}, -1, locus);
 }
 
+bool
+HIRCompileBase::lvalue_p (const_tree ref)
+{
+  const enum tree_code code = TREE_CODE (ref);
+
+  switch (code)
+    {
+    case REALPART_EXPR:
+    case IMAGPART_EXPR:
+    case COMPONENT_REF:
+      return lvalue_p (TREE_OPERAND (ref, 0));
+
+    case COMPOUND_LITERAL_EXPR:
+    case STRING_CST:
+    case CONST_DECL:
+    case INTEGER_CST:
+      return true;
+
+    case MEM_REF:
+    case TARGET_MEM_REF:
+      /* MEM_REFs can appear from -fgimple parsing or folding, so allow them
+	 here as well.  */
+    case INDIRECT_REF:
+    case ARRAY_REF:
+    case VAR_DECL:
+    case PARM_DECL:
+    case RESULT_DECL:
+    case ERROR_MARK:
+      return (TREE_CODE (TREE_TYPE (ref)) != FUNCTION_TYPE
+	      && TREE_CODE (TREE_TYPE (ref)) != METHOD_TYPE);
+
+    case BIND_EXPR:
+      return TREE_CODE (TREE_TYPE (ref)) == ARRAY_TYPE;
+    case PLUS_EXPR:
+    case MINUS_EXPR:
+    case MULT_EXPR:
+    case POINTER_PLUS_EXPR:
+    case POINTER_DIFF_EXPR:
+    case MULT_HIGHPART_EXPR:
+    case TRUNC_DIV_EXPR:
+      return false;
+    default:
+      return false;
+    }
+}
+
 } // namespace Compile
 } // namespace Rust

Diff for: gcc/rust/backend/rust-compile-base.h

@@ -30,6 +30,7 @@ class HIRCompileBase
   virtual ~HIRCompileBase () {}
 
   static tree address_expression (tree expr, location_t locus);
+  bool lvalue_p (const_tree ref);
 
 protected:
   HIRCompileBase (Context *ctx) : ctx (ctx) {}

Diff for: gcc/rust/backend/rust-compile-expr.cc

@@ -851,7 +851,7 @@ CompileExpr::visit (HIR::ContinueExpr &expr)
 
       if (!ctx->lookup_label_decl (ref, &label))
 	{
-	  rust_error_at (expr.get_label ().get_locus (),
+	  rust_error_at (expr.get_label ().get_locus (), ErrorCode::E0770,
 			 "failed to lookup compiled label");
 	  return;
 	}
@@ -958,63 +958,15 @@ CompileExpr::visit (HIR::LiteralExpr &expr)
     }
 }
 
-bool
-lvalue_p (const_tree ref)
-{
-  const enum tree_code code = TREE_CODE (ref);
-
-  switch (code)
-    {
-    case REALPART_EXPR:
-    case IMAGPART_EXPR:
-    case COMPONENT_REF:
-      return lvalue_p (TREE_OPERAND (ref, 0));
-
-    case C_MAYBE_CONST_EXPR:
-      return lvalue_p (TREE_OPERAND (ref, 1));
-
-    case COMPOUND_LITERAL_EXPR:
-    case STRING_CST:
-    case CONST_DECL:
-    case INTEGER_CST:
-      return true;
-
-    case MEM_REF:
-    case TARGET_MEM_REF:
-      /* MEM_REFs can appear from -fgimple parsing or folding, so allow them
-	 here as well.  */
-    case INDIRECT_REF:
-    case ARRAY_REF:
-    case VAR_DECL:
-    case PARM_DECL:
-    case RESULT_DECL:
-    case ERROR_MARK:
-      return (TREE_CODE (TREE_TYPE (ref)) != FUNCTION_TYPE
-	      && TREE_CODE (TREE_TYPE (ref)) != METHOD_TYPE);
-
-    case BIND_EXPR:
-      return TREE_CODE (TREE_TYPE (ref)) == ARRAY_TYPE;
-    case PLUS_EXPR:
-    case MINUS_EXPR:
-    case MULT_EXPR:
-    case POINTER_PLUS_EXPR:
-    case POINTER_DIFF_EXPR:
-    case MULT_HIGHPART_EXPR:
-    case TRUNC_DIV_EXPR:
-      return false;
-    default:
-      rust_debug ("unknown");
-      return false;
-    }
-}
-
 void
 CompileExpr::visit (HIR::AssignmentExpr &expr)
 {
   auto lvalue = CompileExpr::Compile (expr.get_lhs (), ctx);
   auto rvalue = CompileExpr::Compile (expr.get_rhs (), ctx);
 
-  if (!lvalue_p (lvalue)
+  bool validl_value = lvalue_p (lvalue);
+
+  if (!validl_value
       || expr.get_lhs ().get_expression_type ()
 	   == HIR::Expr::ExprType::Operator)
     {