Re: saving AC development strength

[Bruce Korb]

Akim Demaille wrote:
> | I have three choices:
> |
> | 1.  changequote to something certain to not be confused (probably would
> |     have been a really good idea way back when, but likely not now)
> | 2.  replace autoconf-special characters with the quadrigraphs
> |     (my current choice)
> | 3.  lexically analyize the user supplied text for square
> |     bracket constructs that confuses M4's quoting scheme.  Then,
> |     if detected, only replace those characters that would enable
> |     M4 to properly not do substitutions in that text.

Did you understand that last sentence?  I don't.  [[I had just
arrived home from a 9 hour drive...]]

  Then, if detected, only replace those characters that would
  keep autoconf's M4 processing from becoming confused.

> | ...I [still] think, not worth doing.
> 
> OK, as long as you are sure you are not quadrigraphing actual M4
> quotes, it's correct.

It's correct, but so are #1 and #3.  The real question is,
"What is the best solution?" given that none of them are
very pleasing....

Here's an example.  Please note that *only* user supplied
text has the quadrigraph substitutions done.  The text I
have control over, I don't do that.  Oh, I still have a question,
too:  Given that I have complete control over the macro, I can
test to see if a full language "push" is required by testing
to see if it is the current language.  Is it worth doing?
The alternative is to blindly push & pop.

> AC_DEFUN([AG_RUN_QUOTING],
>   AC_MSG_CHECKING([whether M4 quotes are handled properly])
>   AC_CACHE_VAL([ag_cv_run_quoting],[
>   if test "${LANGUAGE}" != "C"
>   then
>     ag_poplang=true
>     AC_LANG_PUSH(C)
>   else
>     ag_poplang=false
>   fi
>   AC_TRY_RUN(address@hidden:@include <stumble.h>
> static const char foo@<:@32@:>@ = "@S|@val";
> int main( int argc, char* argv@<:@@:>@ ) {
> return (strlen(foo) == 4) ? 0 : strlen(foo); }],
>     [ag_cv_run_quoting=yes],[ag_cv_run_quoting=no],[ag_cv_run_quoting=no]
>   ) # end of TRY_RUN
>   if $ag_poplang
>   then
>     AC_LANG_POP(C)
>   fi]) # end of CACHE_VAL
>   AC_MSG_RESULT([${ag_cv_run_quoting}])
> 
>   if test "X${ag_cv_run_quoting}" != Xno
>   then
>     @%:@ @S|@xx @<:@ `date` @:>@
> echo okay
>     AC_DEFINE(HAVE_QUOTING,1,
>         [Define this if M4 quotes are handled properly])
>     AG_QUOTING="@S|@{ag_cv_run_quoting}"
>   else
>     AC_DEFINE(NEED_QUOTING,0,
>         [Define this if 'M4 quotes are handled properly' is not true])
>     AG_QUOTING=''
>   fi
>   AC_SUBST([AG_QUOTING])
> ]) # end of AC_DEFUN of AG_RUN_QUOTING

============== The source definitions: ===================

> AutoGen Definitions conftest.tpl;
> author = "Bruce Korb";
> group  = ag;
> test   = {
>   name     = "quoting";
>   type     = "run";
>   language = C;
>   check    = "M4 quotes are handled properly";
>   code     = <<- _END_OF_CODE_
>         #include <stumble.h>
>         static const char foo[32] = "$val";
>         int main( int argc, char* argv[] ) {
>         return (strlen(foo) == 4) ? 0 : strlen(foo); }
>         _END_OF_CODE_;
> 
>   action   = { yes; act-type=define; act-text = "1"; };
>   action   = { no;  act-type=define; act-text = "0"; };
>   action   = { yes; act-type=subst;  act-text = "${ag_cv_run_quoting}"; };
>   action   = { yes;
>     act-type = script;
>     act-text = <<- _END_OF_SCRIPT_
>         # $xx [ `date` ]
>         echo okay
>         _END_OF_SCRIPT_; };
> };

-- 

Bruce Korb <first initial + last name at gnu dot org>
AG URL: http://autogen.sourceforge.net