[SSSD] [PATCHES] Improve portability of autoconf and automake

Lukas Slebodnik lslebodn at redhat.com
Tue Sep 3 14:33:03 UTC 2013


On (03/09/13 12:15), Sumit Bose wrote:
>On Mon, Sep 02, 2013 at 07:04:22PM +0200, Lukas Slebodnik wrote:
>> ehlo
>> 
>> Patches are attached.
>
>I haven't tested to patches so far but already have some comments.
>
>bye,
>Sumit
>
>> 
>> LS
>
>> From 6e3b789f4b24198b2ec4b40fb09e8b97e578044a Mon Sep 17 00:00:00 2001
>> From: Lukas Slebodnik <lslebodn at redhat.com>
>> Date: Sat, 31 Aug 2013 01:12:01 +0200
>> Subject: [PATCH 2/9] AUTOTOOLS: add check for type intptr_t
>> 
>> We check whether HAVE_INTPTR_T is defined in definition of macro
>> discard_const_p, but autootols macro AC_CHECK_TYPE did not generate it.
>> ---
>>  src/external/sizes.m4 | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>> 
>> diff --git a/src/external/sizes.m4 b/src/external/sizes.m4
>> index 53df61dedc3ae748c50ca9a3935632087834155d..1018d846016541043d81fb2a53609ad9c562071a 100644
>> --- a/src/external/sizes.m4
>> +++ b/src/external/sizes.m4
>> @@ -37,8 +37,7 @@ AC_CHECK_SIZEOF(off_t)
>>  AC_CHECK_SIZEOF(size_t)
>>  AC_CHECK_SIZEOF(ssize_t)
>>  
>> +AC_CHECK_TYPES([intptr_t])
>>  AC_CHECK_TYPE(intptr_t, long long)
>>  AC_CHECK_TYPE(uintptr_t, unsigned long long)
>>  AC_CHECK_TYPE(ptrdiff_t, unsigned long long)
>
>I guess we missed the change of AC_CHECK_TYPE in Autoconf 2.14 where the
>style used above still worked. If I understand the docs correctly it
>should still work, but you should remove the old AC_CHECK_TYPE for
>intptr_t.

just a comment to this point.

It may be litle bit confusing.
There are 3 macros with similar names.
AC_CHECK_TYPE (type, [action-if-found], [action-if-not-found],
                     [includes = ‘AC_INCLUDES_DEFAULT’])
AC_CHECK_TYPES (types, [action-if-found], [action-if-not-found],
                     [includes = ‘AC_INCLUDES_DEFAULT’])
And obsolete macro:
AC_CHECK_TYPE (type, default)
   --If the type type is not defined, define it to be the C (or C++) builtin
     type default, e.g., ‘short int’ or ‘unsigned int’.
   --missing types are defined using #define and not typedef

I hope we used obsolete version. There is a patter how to rewrite it using
new macro. We can ged rid of them.

And now about non obsolete versions.

There is a difference between AC_CHECK_TYPE and AC_CHECK_TYPES
The second version: For each type of the types that is defined,
    define HAVE_type

>> +AC_CHECK_TYPES([intptr_t])
    -> this generate HAVE_INTPTR_T if exists intptr_t
>>  AC_CHECK_TYPE(intptr_t, long long)
    -> this generate "#define intptr_t longlong" unless exists intptr_t

And here is how discard_const_p is defined.

#ifndef discard_const_p
#if defined(__intptr_t_defined) || defined(HAVE_INTPTR_T)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^     ^^^^^^^^^^^^^^^^^^^^^
    This is not portable          This was not generated by autoconf
# define discard_const_p(type, ptr) ((type *)((intptr_t)(ptr)))
#else
# define discard_const_p(type, ptr) ((type *)(ptr))
#endif
#endif

If intptr_t is not default(builtin) type, we will define it in macro
AC_CHECK_TYPE (new one or obsolete).
Which branch of discard_const_p should be used?

I need to know how to use macro.

And the second question. Do wee need defined HAVE_type for all types?
(only HAVE_INTPTR_T is used in code)

LS



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