| // Copyright 2025 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| // This test is informational and documents a pattern not handled by |
| // `spanify` which is thankfully rarely used in Chromium. |
| |
| // A well-meaning human author could rewrite this to a `std::array`... |
| using EightIntegers = int[8]; |
| |
| unsigned UnsafeIndex(); |
| |
| // (continued) ...and then this function would continue to compile |
| // happily, but would now be broken. |
| // |
| // As a C-style array, `klaus` would decay into a pointer. This has |
| // pass-by-reference (by-pointer) semantics. |
| // As a `std::array`, `klaus` is passed _by value_, and this function |
| // becomes meaningless. |
| // |
| // A motivating example exists (existed) in `box_reader.h`, where an |
| // alias akin to `EightIntegers` was set up [1] and used to pass an |
| // array (decayed into a pointer) [2], surprisingly breaking unit |
| // tests. |
| // |
| // [1] |
| // https://source.chromium.org/chromium/chromium/src/+/main:media/formats/mp4/box_reader.h;l=36;drc=e1cad868d343b4300d0ea75193190b3b24a94f07 |
| // [2] |
| // https://source.chromium.org/chromium/chromium/src/+/main:media/formats/mp4/box_reader.h;l=158;drc=e1cad868d343b4300d0ea75193190b3b24a94f07 |
| void MutateIntegers(EightIntegers klaus) { |
| klaus[UnsafeIndex()] = 0; |
| } |
| |
| // No rewrite expected (?). |
| void WouldButDoesntInduceArrayification() { |
| EightIntegers klaus; |
| MutateIntegers(klaus); |
| } |
