String Switch Lowering

[H. S. Teoh]

On Sat, Jan 27, 2018 at 09:22:07PM +0000, timotheecour via Digitalmars-d wrote:
[...]
> ```
> 28  dscanner                            0x000000010d59f428 @safe void
> std.getopt.getoptImpl!(std.getopt.config, immutable(char)[], bool*,
> immutable(char)[], bool*, immutable(char)[], bool*, immutable(char)[],
> bool*, immutable(char)[], bool*, immutable(char)[], bool*,
> immutable(char)[], bool*, immutable(char)[], bool*, immutable(char)[],
> bool*, immutable(char)[], bool*, immutable(char)[], bool*,
> immutable(char)[], bool*, immutable(char)[], bool*, immutable(char)[],
> bool*, immutable(char)[], bool*, immutable(char)[], immutable(char)[]*,
> immutable(char)[], immutable(char)[]*, immutable(char)[], bool*,
> immutable(char)[], immutable(char)[][]*, immutable(char)[], bool*,
> immutable(char)[], bool*, immutable(char)[], bool*, immutable(char)[],
> bool*).getoptImpl(ref immutable(char)[][], ref std.getopt.configuration, ref
> std.getopt.GetoptResult, ref std.getopt.GetOptException,
> void[][immutable(char)[]], void[][immutable(char)[]], std.getopt.config,
> immutable(char)[], bool*, immutable(char)[], bool*, immutable(char)[],
> bool*, immutable(char)[], bool*, immutable(char)[], bool*,
> immutable(char)[], bool*, immutable(char)[], bool*, immutable(char)[],
> bool*, immutable(char)[], bool*, immutable(char)[], bool*,
> immutable(char)[], bool*, immutable(char)[], bool*, immutable(char)[],
> bool*, immutable(char)[], bool*, immutable(char)[], bool*,
> immutable(char)[], immutable(char)[]*, immutable(char)[],
> immutable(char)[]*, immutable(char)[], bool*, immutable(char)[],
> immutable(char)[][]*, immutable(char)[], bool*, immutable(char)[], bool*,
> immutable(char)[], bool*, immutable(char)[], bool*) + 460
> ```
> 
> https://dlang.org/blog/2017/12/20/ds-newfangled-name-mangling/ doesn't
> seem to help in cases like that

This has nothing to do with name mangling. The mangling itself may be
relatively small (and probably is, judging from the amount of repetition
in the signature above), but what you're looking at is the *demangled*
identifier. That's going to be big no matter what, unless we
fundamentally change the way getopt() is implemented.

I proposed a compile-time introspected getopt() replacement before, only
to get laughed at by Andrei.  So I guess that means, don't expect to see
that in Phobos anytime soon.  But I might post the code on github
sometime for those who would benefit from it.  Basically, instead of
taking a ridiculously long argument list, you create a struct whose
members (together with some UDAs) define what the options are, any
associated help text, etc., and just call it with the struct type as
argument.  It does its thing, and returns the struct populated with the
values retrieved from the command-line.  There are a few more features,
but that's the gist of it.


T

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