I'm currently developing a language server for D that uses the DMD frontend to perform its tasks, but one thing I'm stumped on is how to deal with templates and UFCS. From the checking around I've done within the compiler, I haven't really found a function that can evaluate only that the first argument can be used with a specific template function, but not check any other arguments or unrelated constraints.

Without the ability to perform partial template evaluation, completion from libraries such as std.algorithm would be unwieldy and inaccurate, and the completion suggestions would be about as bad as DCD's, or would be hardcoded only for standard library functions.

I know that there was already talk about getting a DMD-based language server off the ground before I started this project myself; I would appreciate it if I could get some help on solving this issue (either by suggesting methods for partial evaluation or creating them if none are completely workable), so that I can help accomplish this. Thank you.