fix Issue 18114 - regex performance regression

[MartinNowak]

• reduce copying of fat structs
• optimize layouts and opAssign of Captures

WIP: still need to figure out how to best handle ref passing of ctRegex

[dlang-bot]

Thanks for your pull request, @MartinNowak!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	18114	regression	[Reg 2.078] regex performance regression

[MartinNowak]

Somewhat tricky, but would be best if we could deprecate usage of ctRegexs as mutable Regex, instead making "logically const" copies.
https://ci.dlang.io/blue/organizations/jenkins/dlang-org%2Fphobos/detail/PR-5981/1/pipeline/184#step-334-log-10

[DmitryOlshansky]

LGTM!

And thanks for figuring it out

[DmitryOlshansky]

I recall some code that broke because of this change on Jenkins auto-tester.

Dunno if we should could overload both by ref and bu value

[n8sh]

If that's the problem would replacing ref with auto ref fix it?

[wilzbach]

I recall some code that broke because of this change on Jenkins auto-tester.

Yeah. Higgs fails:

parser/lexer.d(548): Error: none of the overloads of 'match' are callable using argument types (Wrapper), candidates are:
parser/lexer.d(335):        parser.lexer.StrStream.match(wstring str)
parser/lexer.d(351):        parser.lexer.StrStream.match(Regex!wchar re)
parser/lexer.d(664): Error: none of the overloads of 'match' are callable using argument types (Wrapper), candidates are:
parser/lexer.d(335):        parser.lexer.StrStream.match(wstring str)
parser/lexer.d(351):        parser.lexer.StrStream.match(Regex!wchar re)
parser/lexer.d(687): Error: none of the overloads of 'match' are callable using argument types (Wrapper), candidates are:
parser/lexer.d(335):        parser.lexer.StrStream.match(wstring str)
parser/lexer.d(351):        parser.lexer.StrStream.match(Regex!wchar re)
parser/lexer.d(699): Error: none of the overloads of 'match' are callable using argument types (Wrapper), candidates are:
parser/lexer.d(335):        parser.lexer.StrStream.match(wstring str)
parser/lexer.d(351):        parser.lexer.StrStream.match(Regex!wchar re)
makefile:77: recipe for target 'test' failed

https://ci.dlang.io/blue/organizations/jenkins/dlang-org%2Fphobos/detail/PR-5981/1/pipeline

[MartinNowak]

Rebased and ready to be pulled.
5 ❤️s if someone figures out how to deprecate usage of ctRegex as mutable regex. Casting immutable data (stored in const object file space) to a mutable ref is an ugly workaround.

[MartinNowak]

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