I've been getting some weird linker errors around main() when I declare a struct with a destructor. Is it possible that exception code is being generated even though I have the -betterC flag enabled?

//Example code:
extern(C) void main()
{
	auto window = Window("Hello", 0, 0, 800, 600);
	while(window.IsLive)
		window.Update;
}

On Sunday, 8 December 2019 at 19:29:23 UTC, Marcel wrote:
> I've been getting some weird linker errors around main() when I declare a struct with a destructor. Is it possible that exception code is being generated even though I have the -betterC flag enabled?
>
> //Example code:
> extern(C) void main()
> {
> 	auto window = Window("Hello", 0, 0, 800, 600);
> 	while(window.IsLive)
> 		window.Update;
> }

Struct destructors should work in betterC. It would be helpful if you can paste the errors.

On Sunday, 8 December 2019 at 19:36:40 UTC, Mike Parker wrote:
> Struct destructors should work in betterC. It would be helpful if you can paste the errors.

extern(C) void main()
{
	auto pool = ObjectPool!(int)(100);
	auto a = pool.Acquire;
	pool.Release(*a);
}

This code generates the two following errors:

1>Test.obj : error LNK2019: unresolved external symbol _d_enter_cleanup referenced in function "?dtor$5@?0?"ref Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array.opAssign(const(Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array))" (_D11Collections6Arrays__T5ArrayTSQBf11ObjectPools__T10ObjectPoolTiTS6Memory10Allocators16DefaultAllocatorZQCc5EntryTQBxZQDr8opAssignMFNcxSQFgQEw__TQEsTQEpTQDkZQFeZSQGgQFw__TQFsTQFpTQEkZQGe)@4HA" (?dtor$5@?0?"ref Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array.opAssign(const(Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array))" (_D11Collections6Arrays__T5ArrayTSQBf11ObjectPools__T10ObjectPoolTiTS6Memory10Allocators16DefaultAllocatorZQCc5EntryTQBxZQDr8opAssignMFNcxSQFgQEw__TQEsTQEpTQDkZQFeZSQGgQFw__TQFsTQFpTQEkZQGe)@4HA)

1>Test.obj : error LNK2019: unresolved external symbol _d_leave_cleanup referenced in function "?dtor$5@?0?"ref Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array.opAssign(const(Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array))" (_D11Collections6Arrays__T5ArrayTSQBf11ObjectPools__T10ObjectPoolTiTS6Memory10Allocators16DefaultAllocatorZQCc5EntryTQBxZQDr8opAssignMFNcxSQFgQEw__TQEsTQEpTQDkZQFeZSQGgQFw__TQFsTQFpTQEkZQGe)@4HA" (?dtor$5@?0?"ref Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array.opAssign(const(Collections.Arrays.Array!(Collections.ObjectPools.ObjectPool!(int, Memory.Allocators.DefaultAllocator).ObjectPool.Entry, Memory.Allocators.DefaultAllocator).Array))" (_D11Collections6Arrays__T5ArrayTSQBf11ObjectPools__T10ObjectPoolTiTS6Memory10Allocators16DefaultAllocatorZQCc5EntryTQBxZQDr8opAssignMFNcxSQFgQEw__TQEsTQEpTQDkZQFeZSQGgQFw__TQFsTQFpTQEkZQGe)@4HA)

On Sunday, 8 December 2019 at 19:57:11 UTC, Marcel wrote:
> On Sunday, 8 December 2019 at 19:36:40 UTC, Mike Parker wrote:
>> [...]
>
> extern(C) void main()
> {
> 	auto pool = ObjectPool!(int)(100);
> 	auto a = pool.Acquire;
> 	pool.Release(*a);
> }
>
> [...]

Ok, I found a way to make this work by writing "nothrow:" inside each struct and module. Is this normal?

On Sunday, 8 December 2019 at 19:29:23 UTC, Marcel wrote:
> Is it possible that exception code is being generated even though I have the -betterC flag enabled?

Yes, a cleanup/finally is used, apparently in an opAssign. - These 2 symbols are apparently used to prevent too aggressive LLVM optimizations and are normally provided in druntime here [1]; you can add the 2 one-liners manually in a betterC project.

[1] https://github.com/ldc-developers/druntime/blob/d363d27e119e7cc41b8fd5ef2145d8a7ad140080/src/ldc/eh_msvc.d#L593-L606

On Sunday, 8 December 2019 at 20:58:44 UTC, kinke wrote:
> On Sunday, 8 December 2019 at 19:29:23 UTC, Marcel wrote:
>> Is it possible that exception code is being generated even though I have the -betterC flag enabled?
>
> Yes, a cleanup/finally is used, apparently in an opAssign. - These 2 symbols are apparently used to prevent too aggressive LLVM optimizations and are normally provided in druntime here [1]; you can add the 2 one-liners manually in a betterC project.
>
> [1] https://github.com/ldc-developers/druntime/blob/d363d27e119e7cc41b8fd5ef2145d8a7ad140080/src/ldc/eh_msvc.d#L593-L606

Perfect! Thank you very much!