Re: [PATCH] regex: fix a SIZE_MAX macro redefinition warning

[Ramsay Jones <ramsay@ramsayjones.plus.com>]

On 05/06/16 08:15, Johannes Schindelin wrote:
> Hi Ramsay,
> 
> thanks for working on this!
> 
> On Sat, 4 Jun 2016, Ramsay Jones wrote:
> 
>> diff --git a/Makefile b/Makefile
>> index 0d59718..3f6c70a 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -1987,7 +1987,7 @@ endif
>>  
>>  ifdef NO_REGEX
>>  compat/regex/regex.sp compat/regex/regex.o: EXTRA_CPPFLAGS = \
>> -	-DGAWK -DNO_MBSUPPORT
>> +	-DGAWK -DNO_MBSUPPORT -DHAVE_STDINT_H
> 
> Maybe a comment here, something like "the fallback regex implementation
> *requires* stdint.h"?

The original version of this patch looked like this:

  diff --git a/compat/regex/regcomp.c b/compat/regex/regcomp.c
  index fba5986..d8bde06 100644
  --- a/compat/regex/regcomp.c
  +++ b/compat/regex/regcomp.c
  @@ -18,8 +18,6 @@
      Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
      02110-1301 USA.  */
   
  -#include <stdint.h>
  -
   static reg_errcode_t re_compile_internal (regex_t *preg, const char * pattern,
   					  size_t length, reg_syntax_t syntax);
   static void re_compile_fastmap_iter (regex_t *bufp,
  diff --git a/compat/regex/regex.c b/compat/regex/regex.c
  index 6aaae00..5cb23e5 100644
  --- a/compat/regex/regex.c
  +++ b/compat/regex/regex.c
  @@ -60,6 +60,7 @@
      GNU regex allows.  Include it before <regex.h>, which correctly
      #undefs RE_DUP_MAX and sets it to the right value.  */
   #include <limits.h>
  +#include <stdint.h>
   
   #ifdef GAWK
   #undef alloca

So, just move the unconditional inclusion to the start of the compilation
unit root file, before the #include of the regex_internal.h header.

In some ways this is a better fix, because it makes it clear that, currently,
the compat/regex code requires <stdint.h>. This would remove the need for
such a comment.

This effectively makes the conditional inclusion of <stdint.h>, and the SIZE_MAX
fallback, in regex_internal.h dead code. (The C99 standard _requires_ the
definition of SIZE_MAX in <stdint.h>, thankfully! ;-). So, I was tempted to
remove them as part of the patch. However, I also wanted to minimize the changes
to the regex code, just in case we ever wanted to re-import a newer version
from upstream. Setting HAVE_STDINT_H seemed like a good solution, but maybe the
first patch would be more honest?

As I said earlier, I was a little concerned about the 'unconditional' aspect of
the inclusion of <stdint.h>. At one time we wanted to support systems that didn't
have <stdint.h> (or didn't have <inttypes.h> but did have <stdint.h>). However,
it has been several months and we have not heard anyone scream, so ...

It is slightly amusing that the reason you #included <stdint.h> was to get the
definition of 'intptr_t' and the C standard states that this type is optional.
In practice, I suspect that the number of platforms which do not define 'intptr_t'
and 'uintptr_t' in the <stdint.h> header is rather small.

Having said that ... If I'm reading the code/config correctly, HP-NONSTOP would
be failing to compile at the moment. (Although it has <stdint.h>, it does not
define 'intptr_t' - ie it defines 'NO_REGEX = YesPlease' and 'NO_INTPTR_T = \
UnfortunatelyYes').

> Other than that, I think this patch is an improvement.

Thanks. What do you think of replacing it with the original patch (above)?

ATB,
Ramsay Jones