Would it be possible for the maintainers of GDC and LDC to both support certain switches in use by the other compiler in order to reduce the frustration of this one grumpy user?

I keep switching back and forth between -frelease and -release,
and -march and -mcpu (is that even correct)?

I’m not sure what I should be doing to get LDC correctly matched with -mtune and -march.

I have of course ended up having to write batch files to abstract these annoyances away. When I’m examining generated code for my own correctness in godbolt.org Matt Godbolt’s Compiler Explorer, that’s when it drives me bonkers having to correct the switches when I switch between compilers.

It’s just a small thing, I know, but it would be nice to harmonise, and not too much work.

Take a look at ldmd and gdmd, they translate from dmd's arguments to ldc/gdc.