implement DIP1008 enabling @nogc for 'throw new Throwable;'

[WalterBright]

It adds the -dip1006 to enable it. Of course, throwing that switch won't work until the druntime end is done.

The idea is to recognize throw new Throwable and call _d_newThrowable() instead of _d_newclass(). When caught, add a call to _d_delThrowable() at the end of the catch block.

The druntime will use malloc and free for these. Reference counting is used to handle rethrowing. It should mix naturally with Throwables allocated via other means, like static and the GC.

[thewilsonator]

Please update ddmd/declaration.h as well

[WalterBright]

Please update ddmd/declaration.h as well

Already there.

[ibuclaw]

Already there.

Maybe they meant expression.h

[WalterBright]

done

[mathias-lang-sociomantic]

DIP1006 ? Thats not DIP1006.

[mdparker]

Given the state of the DIP PR queue, this is likely going to be DIP 1008.

[WalterBright]

Yes, I mistakenly thought 1006 was unassigned. I'll update the PR when assigned a proper number.

[wilzbach]

For reference: the link to DIP 1008 is https://github.com/dlang/DIPs/blob/master/DIPs/DIP1008.md

[wilzbach]

@WalterBright how about adding an actual example that ensures that one can throw in @nogc? Once #6742 is merged, CodeCov should start to complain again ;-)

[WalterBright]

Needs druntime PR to be pulled first.

[JackStouffer]

Just manually checked. Looks like the cycle is real, but it only exists in version(unittest).

[WalterBright]

Looks like the cycle is real,

Sorry, posted my comment in the wrong place. Moved it here: dlang/phobos#4712

[dlang-bot]

Thanks for your pull request, @WalterBright!

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[andralex]

OK, time to move this along. Rebase first of all?

[WalterBright]

rebased

[ibuclaw]

Missing argument to actually test the dip.

[WalterBright]

done

[WalterBright]

but it'll never work until the druntime changes are pulled, so I disabled it

[mathias-lang-sociomantic]

That's actually a good thing, it will prevent this P.R. from being pulled before it's ready.

[stefan-koch-sociomantic]

what @mathias-lang-sociomantic said!

[WalterBright]

Which came first, the chicken or the egg?

either this or dlang/druntime#1804 has to be pulled first. I suggest this one.