Remove callStructDtorsDuringGC rt flag

[edi33416]

Struct dtors should always be called; we shouldn't allow configuration files to change the meaning of the language.

Edit: Anyone knows when and why was this introduced? Any projects using it?

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[thewilsonator]

This i separate from the not calling the GC at all on shutdown, right?

[edi33416]

This i separate from the not calling the GC at all on shutdown, right?

As far as I can tell, this is only used by structTypeInfoSize to determine if _d_newitem needs to store a ptr to the dtor. I don't think this is related with the GC shutdown.

[jacob-carlborg]

This needs to go through the depreciation process.

[andralex]

I wonder how to deprecate this - issue a message at runtime to stderr if the flag is false?

[Geod24]

Edit: Anyone knows when and why was this introduced? Any projects using it?

A long time ago, the GC would not call destructors on heap allocated struct. When it was fixed, I think this was put as a transitional step. #864

[rainers]

I'm fine with removal. AFAICT it has never been documented so we might consider it internal and skip a deprecation, or make that a short one.
Printing a deprecation message in lifetime_init if the setting is found seems like the obvious choice.

[rainers]

Please remove scoping/indentation, too. Later it will just confuse people why it is there sometimes, and sometimes not.

[jacob-carlborg]

I wonder how to deprecate this - issue a message at runtime to stderr if the flag is false?

I would print the message as long as the flag has been passed to the application, regardless of the value of the flag.

Regarding stderr. I don't know if we should worry about this, but on AppVeyor, if any output occurs on stderr the build is failed.

When the deprecation should turn into an error we can throw an exception.

[jacob-carlborg]

AFAICT it has never been documented so we might consider it internal and skip a deprecation, or make that a short one.

Are any of the druntime flags documented?

[wilzbach]

AFAICT it has never been documented so we might consider it internal and skip a deprecation, or make that a short one.

Are any of the druntime flags documented?

No. "Luckily", druntime is chronically under-documented.
The only documentation of --DRT is here: https://dlang.org/spec/garbage.html#gc_config (for the GC bits).

[jacob-carlborg]

I think it should be deprecated anyway. It's not difficult to do. For me it's enough for it to be deprecated for one release.

[JohanEngelen]

'// this is run before static ctors, so it is safe to modify immutables'

Wow, incredible. Very nice to get rid of this kind of UB in druntime code.

[dnadlinger]

Wow, incredible. Very nice to get rid of this kind of UB in druntime code.

Immutable globals can be initialised in static constructors, so whether this is UB or not is questionable.

[andralex]

@edi33416 ?

[edi33416]

@andralex @jacob-carlborg I opened #2513 for the deprecation of the feature