…flutter/engine#46376)

…135755)

flutter/engine@c52251a...d5fcd78

2023-09-29 [email protected] Roll Skia from a80c164ffb8a to 9f8242377455 (1 revision) (flutter/engine#46406)
2023-09-29 [email protected] [Impeller] Implements canvas recorder with trace serializer (flutter/engine#46376)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC [email protected],[email protected],[email protected] on the revert to ensure that a human
is aware of the problem.

To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

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…s not set. (#46476)

Internal bug: b/303067268

#46376 is causing a breakage to the internal engine build because of https://github.com/flutter/engine/blob/150d1b6ab51f34c07e21fc32ef76e4842edd4d04/impeller/aiks/canvas_recorder.h#L58-L62. Internally, we do not set `IMPELLER_TRACE_CANVAS`.

It looks like the cause is that the internal toolchain causes the `static_assert` to be compiled even though the template is not instantiated.

@chingjun helped me to figure out the following:

https://stackoverflow.com/questions/5246049/c11-static-assert-and-template-instantiation points us to the spec. In the later version (ISO/IEC 14882:2017(E)):

> The program is ill-formed, no diagnostic required, if ... no valid specialization can be generated for a template or a substatement of a constexpr if statement (9.4.1) within a template and the template is not instantiated,

<details>

<summary>The relevant section</summary>

![The relevant section of the spec](https://github.com/flutter/engine/assets/7111741/4503efcd-9479-4c7a-b4a1-7302dea1653b)

</details>

Interpretation: the compiler can either choose to emit the error caused by the `static_assert` or not. Currently the compiler used by the build here on LUCI does not; internally it does.

For example, the following links shows that simply changing the Clang version affects whether the error appears or not for a minimal template.

- ok: https://godbolt.org/z/n9nYrcvcP
- not ok: https://godbolt.org/z/fWcvdcn35

Hence, `#ifdef` out the class instead of using a `static_assert` for more consistent behavior across these two toolchains.

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

…lutter#135755)

flutter/engine@c52251a...d5fcd78

2023-09-29 [email protected] Roll Skia from a80c164ffb8a to 9f8242377455 (1 revision) (flutter/engine#46406)
2023-09-29 [email protected] [Impeller] Implements canvas recorder with trace serializer (flutter/engine#46376)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC [email protected],[email protected],[email protected] on the revert to ensure that a human
is aware of the problem.

To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

This implements a portion of impeller canvas recorder that just prints
log statements to understand what is getting rendered in impeller when
executing code from the framework. Eventually this should get moved to
the displaylist layer when we have golden and interactive tests at that
layer.

This was useful for me to debug a fidelity issue, the hope is that
others will find it useful and can expand it as necessary. Eventually
the recordings can be used to generate tests.

design doc:
[go/impeller-canvas-recorder](http://goto.google.com/impeller-canvas-recorder)

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide] and the [C++,
Objective-C, Java style guides].
- [ ] I listed at least one issue that this PR fixes in the description
above.
- [x] I added new tests to check the change I am making or feature I am
adding, or the PR is [test-exempt]. See [testing the engine] for
instructions on writing and running engine tests.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I signed the [CLA].
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
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[Tree Hygiene]: https://github.com/flutter/flutter/wiki/Tree-hygiene
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[Flutter Style Guide]:
https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo
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https://github.com/flutter/flutter/wiki/Testing-the-engine
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…s not set. (#46476)

Internal bug: b/303067268

#46376 is causing a breakage to the internal engine build because of https://github.com/flutter/engine/blob/150d1b6ab51f34c07e21fc32ef76e4842edd4d04/impeller/aiks/canvas_recorder.h#L58-L62. Internally, we do not set `IMPELLER_TRACE_CANVAS`.

It looks like the cause is that the internal toolchain causes the `static_assert` to be compiled even though the template is not instantiated.

@chingjun helped me to figure out the following:

https://stackoverflow.com/questions/5246049/c11-static-assert-and-template-instantiation points us to the spec. In the later version (ISO/IEC 14882:2017(E)):

> The program is ill-formed, no diagnostic required, if ... no valid specialization can be generated for a template or a substatement of a constexpr if statement (9.4.1) within a template and the template is not instantiated,

<details>

<summary>The relevant section</summary>

![The relevant section of the spec](https://github.com/flutter/engine/assets/7111741/4503efcd-9479-4c7a-b4a1-7302dea1653b)

</details>

Interpretation: the compiler can either choose to emit the error caused by the `static_assert` or not. Currently the compiler used by the build here on LUCI does not; internally it does.

For example, the following links shows that simply changing the Clang version affects whether the error appears or not for a minimal template.

- ok: https://godbolt.org/z/n9nYrcvcP
- not ok: https://godbolt.org/z/fWcvdcn35

Hence, `#ifdef` out the class instead of using a `static_assert` for more consistent behavior across these two toolchains.

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style