ImportC can now automatically run the preprocessor

[Adam D Ruppe]

On Monday, 16 May 2022 at 03:12:47 UTC, Walter Bright wrote:
> This is replacing C #define's with D constructions, right?

No. It is about not having to. Instead of converting to D (and 
being forced to fail in certain cases), you just mixinC.

> I'm not going to pretend this can ever be a complete 100% 
> solution, after all:
>
>    #define BEGIN {
>    #define END }
>
> What can one do with that? Phooey.

This is an example I showed *can actually work* in the message 
you're quoting. Of course, they'd have to be paired in the mixed 
in block, but it would work once you get a complete ast node 
assembled.

Very similar to D's

enum string BEGIN = "{";
enum string END = "}";
mixin(BEGIN ~ "stuff" ~ END);


mixin(BEGIN) obviously not going to work, but if you concat the 
strings to form a complete statement, you have something that can 
be used.

The C preprocessor is very similar to string replacement and 
concatenation.

> But I still don't understand - why mixin this stuff?
> Why would someone want to type C code into a D source file?

Why would someone want to use inline assembler? Why would someone 
want to use CTFE on C? Why would someone want to type __import in 
a C file?