Add src/common/unsafe_buffers.h

Allow for line-by-line control of unsafe buffers warnings.

Bug: b/436880895
Change-Id: I609d60c83611037f39d541d5b8c9aba98a6656a7
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6886308
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Auto-Submit: Tom Sepez <tsepez@chromium.org>

Author: tsepez

src/common/unsafe_buffers.h

@@ -0,0 +1,37 @@
+//
+// Copyright 2025 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+// unsafe_buffers.h: exempts code from unsafe buffers warnings. Based upon
+// https://source.chromium.org/chromium/chromium/src/+/main:base/compiler_specific.h
+
+#ifndef COMMON_UNSAFE_BUFFERS_H_
+#define COMMON_UNSAFE_BUFFERS_H_
+
+#if defined(__clang__) && defined(__has_attribute)
+#    if __has_attribute(unsafe_buffer_usage)
+#        define ANGLE_UNSAFE_BUFFER_USAGE [[clang::unsafe_buffer_usage]]
+#    endif
+#endif
+#if !defined(ANGLE_UNSAFE_BUFFER_USAGE)
+#    define ANGLE_UNSAFE_BUFFER_USAGE
+#endif
+
+// Formatting is off so that we can put each _Pragma on its own line.
+// clang-format off
+#if defined(UNSAFE_BUFFERS_BUILD)
+#    define ANGLE_UNSAFE_BUFFERS(...)                  \
+         _Pragma("clang unsafe_buffer_usage begin")    \
+         __VA_ARGS__                                   \
+         _Pragma("clang unsafe_buffer_usage end")
+#else
+#    define ANGLE_UNSAFE_BUFFERS(...) __VA_ARGS__
+#endif
+// clang-format on
+
+// Like ANGLE_UNSAFE_BUFFERS(), but indicates there is a TODO() task.
+#define ANGLE_UNSAFE_TODO(...) ANGLE_UNSAFE_BUFFERS(__VA_ARGS__)
+
+#endif  // COMMON_UNSAFE_BUFFERS_H_

src/libGLESv2.gni

@@ -63,6 +63,7 @@ libangle_common_headers = [
   "src/common/system_utils.h",
   "src/common/tls.h",
   "src/common/uniform_type_info_autogen.h",
+  "src/common/unsafe_buffers.h",
   "src/common/utilities.h",
   "src/common/vector_utils.h",
   "src/libANGLE/CLBitField.h",