[Issue 21716] std.regex performance regression (additional GC allocation)

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21716

--- Comment #1 from Jon Degenhardt <jrdemail2000-dlang at yahoo.com> ---
I have confirmed that Phobos PR #7678
(https://github.com/dlang/phobos/pull/7678) is the cause of the regression. I
expect to submit a PR addressing it tomorrow.

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