[webkit-changes] [WebKit/WebKit] 48d360: [JSC] Fix rounding error for `Intl.DurationFormat`

[SUZUKI Sosuke]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 48d36047a83e40ddfa90ea614825f0f772a4f4e0
      https://github.com/WebKit/WebKit/commit/48d36047a83e40ddfa90ea614825f0f772a4f4e0
  Author: Sosuke Suzuki <aosukeke at gmail.com>
  Date:   2024-10-19 (Sat, 19 Oct 2024)

  Changed paths:
    A JSTests/stress/intl-durationformat-rounding-errors.js
    M JSTests/test262/expectations.yaml
    M Source/JavaScriptCore/runtime/ISO8601.cpp
    M Source/JavaScriptCore/runtime/ISO8601.h
    M Source/JavaScriptCore/runtime/IntlDurationFormat.cpp

  Log Message:
  -----------
  [JSC] Fix rounding error for `Intl.DurationFormat`
https://bugs.webkit.org/show_bug.cgi?id=281501

Reviewed by Yusuke Suzuki.

Our `Intl.DurationFormat` is affected by rounding errors because each unit is summed as a double.
Additionally, very large values cannot fit within a double.

This patch introduces the following changes:

- Each unit is summed using `Int128`.
- Since `Int128` values cannot be formatted with ICU’s `unumf_formatDouble`[1], so we build a
  decimal-formatted string from the `Int128` value and use `unumf_formatDecimal`[2] for formatting.

[1]: https://unicode-org.github.io/icu-docs/apidoc/released/icu4c/unumberformatter_8h.html#a54193ed406316485803e3dac3a96615f
[2]: https://unicode-org.github.io/icu-docs/apidoc/released/icu4c/unumberformatter_8h.html#a6183aa03b43b63b231341770035bace9

* JSTests/stress/intl-durationformat-rounding-errors.js: Added.
(sameValue):
(throw.new.Error):
* JSTests/test262/expectations.yaml:
* Source/JavaScriptCore/runtime/ISO8601.cpp:
(JSC::ISO8601::Duration::totalNanoseconds const):
(JSC::ISO8601::isValidDuration):
* Source/JavaScriptCore/runtime/ISO8601.h:
* Source/JavaScriptCore/runtime/IntlDurationFormat.cpp:
(JSC::int128ToString):
(JSC::buildDecimalFormat):
(JSC::collectElements):

Canonical link: https://commits.webkit.org/285482@main



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