D compiler equivilent of "gcc -E" for debug/view template instantiation(generated) code?

[Mike Parker]

On Friday, 30 July 2021 at 08:38:24 UTC, dangbinghoo wrote:
>
>
> but, where's these switch option documented? it seems it not 
> appears in dmd --help or man dmd, or online document 
> https://dlang.org/dmd-linux.html
>
>

That's what he meant by "hidden" switch. I don't know why it 
isn't documented, but it probably should be.