[webkit-reviews] review granted: [Bug 188146] Use constexpr constructors more instead of NeverDestroyed : [Attachment 346028] Patch

[bugzilla-daemon at webkit.org]

Darin Adler <darin at apple.com> has granted Yusuke Suzuki
<utatane.tea at gmail.com>'s request for review:
Bug 188146: Use constexpr constructors more instead of NeverDestroyed
https://bugs.webkit.org/show_bug.cgi?id=188146

Attachment 346028: Patch

https://bugs.webkit.org/attachment.cgi?id=346028&action=review




--- Comment #2 from Darin Adler <darin at apple.com> ---
Comment on attachment 346028
  --> https://bugs.webkit.org/attachment.cgi?id=346028
Patch

Change seems fine.

Bug title is a bit inaccurate.

Having a constexpr constructor does not affect whether NeverDestroyed is
needed. It does affect whether we can have a global outside a function. If the
constructor is not constexpr it needs to be inside a function so it gets run
the first time the function is installed rather than at load time.

What affects the need for NeverDestroyed is whether the class has a trivial
destructor. If it does then NeverDestroyed is not needed.

In all these cases in this patch we changed both things but they are
independent.

You can have a static without NeverDestroyed if the destructor is trivial. You
can have a global outside a function that uses NeverDestroyed as long as the
entire constructor is all constexpr. (Might need to fix NeverDestroyed
implementation to be sure it’s constructors are constexpr.)