do not generate __fieldPostBlit if this(this) annotated with @disable

[IgorStepanov]

https://issues.dlang.org/show_bug.cgi?id=13633

[IgorStepanov]

@monarchdodra This is a solution of the trouble, which we are discussed. Have you any objections?
I simply disabled generating __fieldPostBlit if this(this) annotated with @disable. This allows to define structs with const struct fields (however you should disable postblit for it).

[monarchdodra]

I think you should file an issue so people that don't know what's going on would understand. I have no idea how dmd works though, so the usual dmd team will have to do the reviewing here.

[WalterBright]

1. this needs a bugzilla issue for it
2. the fieldPostBlit should be disabled if any of the fields have disabled postblits
3. the aggrPostBlit should be disabled if any of postblits[ ] are disabled.

[IgorStepanov]

1. this needs a bugzilla issue for it
2. the fieldPostBlit should be disabled if any of the fields have disabled postblits
3. the aggrPostBlit should be disabled if any of postblits[ ] are disabled.

1. Done: see description.
2. Done: stc variable accumulates storage classes of all field postblits.
3. Done: already been so.

[WalterBright]

This is incorrect.

1. All of postblits[] should be tested for STCdisable
2. All postblits used in fields should be tested for STCdisable

[IgorStepanov]

All of postblits[] should be tested for STCdisable

Ok.

All postblits used in fields should be tested for STCdisable

It's done below.

stc = mergeFuncAttrs(stc, sd2->postblit);
if (stc & STCdisable)
{
     e = NULL;
     break;
}

[IgorStepanov]

All of postblits[] should be tested for STCdisable

Done

[WalterBright]

If any of postblits[] are disabled, then the field postblit should not be generated. I'd write the code above as:

for (size_t i = 0; i < sd->postblits.dim; ++i)
{
    stc |= sd->postblits[i]->storage_class & STCdisable;
}

[IgorStepanov]

Hmm. In which case there cam be many postblits in this point? I think this is situation where user defines postblits with different const modifiers:

struct Foo
{
    @disable this(this) const;
    this(this)
    {
         ...
    }
}

const Foo can not be copied, but we still may copy mutable Foo.
In this case we should generate __fieldPostBlit if at least one posthlit is not @disabled.
If user defines only one postblit, there will be only one element at this point.
Am I right?

[IgorStepanov]

@WalterBright I've added commit which follows your code. You may choose it or only the first commit. (See my explanations before). Thanks.

[IgorStepanov]

@WalterBright Is it ok now? Are you sure that we should disable __fieldPostBlit is any of user postblits is disabled?

[WalterBright]

If any of the fields cannot be copied, and any of the user supplied postblits cannot be used, then copying doesn't work so postblit should be disabled.

[IgorStepanov]

Thanks