Re: fixincludes: replacement for machine_name fix

[Zack Weinberg <zack at wolery dot cumb dot org>]

On Wed, Jan 19, 2000 at 02:58:36PM -0800, Bruce Korb wrote:
> Zack Weinberg wrote:
> > 
> > #if defined linux || defined __linux__
> > 
> > then it will not be modified.  (Yes, that's a real-world example.)
> > This cuts in half the number of headers modified on my system.
> 
> Cool!  Faster, too, I bet.

Not a whole lot, but yes.  It takes (+/-) 4m15s with the patch, 4m30s
without.

I did some poking at performance.  Compiling with optimization on
makes no measurable difference.  Neither does NO_BOGOSITY.  Diking
gnu-regex.o out of the build (which causes us to fall back to libc)
cuts the time to *nine seconds*.  Copying glibc's regex.c over to
gnu-regex.c cuts the time to 27 seconds.  I am confused.  glibc's
regex.c is a newer version of our regex.c; the differences are small,
but I guess they're significant.

> > Bruce: this patch removes the only use of exesel, and therefore will
> > allow us to throw that away.
> 
> Good.  I never liked it anyway.  Do it under separate cover
> after this has been installed and tested.

Will do.

...
> > +   Helper routine and data for the machine_name test and fix.
> > +   machname.h is created by black magic in the Makefile.  */
> > +
> > +#include "machname.h"
> > +
> > +tSCC mn_label_pat[] = "^[ \t]*#[ \t]*if(def)?[ \t]+";
> 
> tSCC mn_label_pat[] = "^[ \t]*#[ \t]*(if|ifndef|ifdef)[ \t]+";

Doh! Thanks for pointing that out.  

> 
> You can combine the three 'if's, but I think
> 
>   tSCC mn_label_pat[] = "^[ \t]*#[ \t]*if(ndef|def)?[ \t]+";
> 
> is less readable and maybe even harder to process,

Agree.

...
> > +  return sizeof mn_name_pat;
> 
> You know, of course, that this is the wrong value.
> If there is only one name in the MN_NAME_PAT, it is
> even guaranteed to be too small.  Pick a random number
> like 64 and blow up if "__some-sort-of-long-name__"
> exceeds that size.  Do it back in fixfixes and don't
> return a value here.

By a handy coincidence, '\<foo\>' is exactly the same length as
'__foo__'.  It is, however, not very nice.  I'll make it as you suggest.

> < +        because comments on #if/#ifdef lines are rare, and strings on
> < +        such lines are illegal.
> ----
> > +        because comments on #if/#ifdef/#ifndef lines are rare,
> > +        and strings on such lines are illegal.

Right.

Revised patch in a few minutes.

zw