From 38d5c5e444cf53567356df1bfc8a117130c7a52e Mon Sep 17 00:00:00 2001
From: Daco Harkes <dacoharkes@google.com>
Date: Tue, 30 Mar 2021 00:12:49 +0000
Subject: [PATCH] [vm/ffi] Array range error message

Closes: https://github.com/dart-lang/sdk/issues/45189

Change-Id: I225a092fd05efe8a6eed7749375ea4c842547fb7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/193404
Auto-Submit: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Siva Annamalai <asiva@google.com>
---
 sdk/lib/_internal/vm/lib/ffi_patch.dart |  2 +-
 tests/ffi/regress_45189_test.dart       | 26 +++++++++++++++++++++++++
 tests/ffi_2/regress_45189_test.dart     | 26 +++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 tests/ffi/regress_45189_test.dart
 create mode 100644 tests/ffi_2/regress_45189_test.dart

diff --git a/sdk/lib/_internal/vm/lib/ffi_patch.dart b/sdk/lib/_internal/vm/lib/ffi_patch.dart
index 75a6e51519b..d2b0d0a7e00 100644
--- a/sdk/lib/_internal/vm/lib/ffi_patch.dart
+++ b/sdk/lib/_internal/vm/lib/ffi_patch.dart
@@ -129,7 +129,7 @@ class Array<T extends NativeType> {
 
   _checkIndex(int index) {
     if (index < 0 || index >= _size) {
-      throw RangeError.range(index, 0, _size);
+      throw RangeError.range(index, 0, _size - 1);
     }
   }
 
diff --git a/tests/ffi/regress_45189_test.dart b/tests/ffi/regress_45189_test.dart
new file mode 100644
index 00000000000..980d1bcfa41
--- /dev/null
+++ b/tests/ffi/regress_45189_test.dart
@@ -0,0 +1,26 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:ffi";
+
+import "package:ffi/ffi.dart";
+import 'package:expect/expect.dart';
+
+class Struct8BytesInlineArrayInt extends Struct {
+  @Array(8)
+  external Array<Uint8> a0;
+}
+
+void main() {
+  final pointer = calloc<Struct8BytesInlineArrayInt>();
+  final array = pointer.ref.a0;
+  try {
+    array[8]; // RangeError: Invalid value: Not in inclusive range 0..8: 8
+  } on RangeError catch (exception) {
+    final toString = exception.toString();
+    Expect.equals(
+        "RangeError: Invalid value: Not in inclusive range 0..7: 8", toString);
+  }
+  calloc.free(pointer);
+}
diff --git a/tests/ffi_2/regress_45189_test.dart b/tests/ffi_2/regress_45189_test.dart
new file mode 100644
index 00000000000..1aff90bc8e7
--- /dev/null
+++ b/tests/ffi_2/regress_45189_test.dart
@@ -0,0 +1,26 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:ffi";
+
+import "package:ffi/ffi.dart";
+import 'package:expect/expect.dart';
+
+class Struct8BytesInlineArrayInt extends Struct {
+  @Array(8)
+  Array<Uint8> a0;
+}
+
+void main() {
+  final pointer = calloc<Struct8BytesInlineArrayInt>();
+  final array = pointer.ref.a0;
+  try {
+    array[8]; // RangeError: Invalid value: Not in inclusive range 0..8: 8
+  } on RangeError catch (exception) {
+    final toString = exception.toString();
+    Expect.equals(
+        "RangeError: Invalid value: Not in inclusive range 0..7: 8", toString);
+  }
+  calloc.free(pointer);
+}