Bug 234504 – [Win] MSVC reports "DownloadBundleWin.cpp(87): error C2362: initialization of 'magic' is skipped by 'goto exit'" with /std:c++20

• Status: RESOLVED
• Resolution: FIXED
• Component: Platform

[Fujii Hironori]

[Win] MSVC reports "DownloadBundleWin.cpp(87): error C2362: initialization of 'magic' is skipped by 'goto exit'" with /std:c++20

> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(87): error C2362: initialization of 'magic' is skipped by 'goto exit'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(80): note: see declaration of 'magic'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(87): note: see declaration of 'exit'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(173): error C2362: initialization of 'footerStartPosition' is skipped by 'goto exit'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(150): note: see declaration of 'footerStartPosition'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(173): note: see declaration of 'exit'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(173): error C2362: initialization of 'footerLength' is skipped by 'goto exit'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(143): note: see declaration of 'footerLength'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(173): note: see declaration of 'exit'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(173): error C2362: initialization of 'footerLengthPosition' is skipped by 'goto exit'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(135): note: see declaration of 'footerLengthPosition'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(173): note: see declaration of 'exit'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(173): error C2362: initialization of 'footerMagicNumber' is skipped by 'goto exit'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(122): note: see declaration of 'footerMagicNumber'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(173): note: see declaration of 'exit'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(173): error C2362: initialization of 'footerMagicNumberPosition' is skipped by 'goto exit'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(115): note: see declaration of 'footerMagicNumberPosition'
> Source\WebCore\platform\network\win\DownloadBundleWin.cpp(173): note: see declaration of 'exit'

[Fujii Hironori]

Created attachment 447584 [details]
Patch

[Fujii Hironori]

Created attachment 447624 [details]
Patch

[Fujii Hironori]

Created attachment 447626 [details]
Patch

[EWS]

Committed r287299 (245451@main): <https://commits.webkit.org/245451@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 447626 [details].

[Radar WebKit Bug Importer]

<rdar://problem/86755997>

[Darin Adler]

Comment on attachment 447626 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=447626&action=review

> Source/WebCore/platform/network/win/DownloadBundleWin.cpp:47
> +};

There should not be a semicolon here.

> Source/WebCore/platform/network/win/DownloadBundleWin.cpp:72
> +    std::unique_ptr<FILE, decltype(&fileCloser)> bundle(bundlePtr, &fileCloser);

Should be able to just write std::unique_ptr with no template arguments and rely on the deduction guide to deduce the argument types.

> Source/WebCore/platform/network/win/DownloadBundleWin.cpp:107
> +    std::unique_ptr<FILE, decltype(&fileCloser)> bundle(bundlePtr, &fileCloser);

Ditto.

[Fujii Hironori]

reopened.

[Fujii Hironori]

Comment on attachment 447626 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=447626&action=review

>> Source/WebCore/platform/network/win/DownloadBundleWin.cpp:72
>> +    std::unique_ptr<FILE, decltype(&fileCloser)> bundle(bundlePtr, &fileCloser);
> 
> Should be able to just write std::unique_ptr with no template arguments and rely on the deduction guide to deduce the argument types.

std::unique_ptr doesn't have the deduction guide.

  c++ - Why does std::unique_ptr not permit type inference? - Stack Overflow
  https://stackoverflow.com/q/41162868

  c++ - Why can't unique_ptr's template arguments be deduced? - Stack Overflow
  https://stackoverflow.com/q/51109767

And, I want to specify a deleter in this case.
And, C++17 lambda type doesn't have the default constructor.
C++20 can compile the following code.
> std::unique_ptr<FILE, decltype(&fileCloser)> bundle(bundlePtr);

[Darin Adler]

(In reply to Fujii Hironori from comment #8)
> std::unique_ptr doesn't have the deduction guide.

I understand why it can’t have one without a deleter; too bad it can’t have one with a deleter. Glad you investigated.

[Fujii Hironori]

Created attachment 447765 [details]
Patch

[EWS]

Committed r287432 (245567@main): <https://commits.webkit.org/245567@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 447765 [details].