Re: [PATCH v3 2/5] powerpc: Add redirection for finitef128, isinf128, and isnanf128

["Gabriel F. T. Gomes" <gabriel at inconstante dot eti dot br>]

On 19 Sep 2017, Tulio Magno Quites Machado Filho wrote:

>"Gabriel F. T. Gomes" <gabriel@inconstante.eti.br> writes:
>
>> The errors are due to the unintended macro expansion of __finitef128 to
>> __redirect_finitef128 in math/bits/mathcalls-helper-functions.h.  In  
>
>AFAIU, the expansion of __finitef128 to __redirect_finitef128 in
>math/bits/mathcalls-helper-functions.h is expected.  The problem happens when
>the same thing doesn't happen in include/math.h too.

I mean unintended in the sense that the expansion of __finitef and
__finitel, which pertain to float and long double, are happening in
s_finite.c, which is the *double* implementation of finite.  Compare that
with s_finitef.c, which only redefines __finitef, leaving the other macros
(__finite and __finitel) untouched.

On the other hand, I agree that my comments did not fully explain the
problem.  They only mention the expansion in mathcalls-helper-functions.h
and do not say anything about the hidden prototypes in include/math.h.

So, how about expanding this paragraph to:

  The errors are due to the unintended macro expansion of __finitef128 to
  __redirect_finitef128 in math/bits/mathcalls-helper-functions.h.  In
  that header, __MATHDECL_1 takes '__finite' and 'f128' as arguments and
  concatenates them.  However, since '__finite' has been redefined in
  s_finite.c, the function declaration becomes __redirect_finitef128:

    extern int __redirect___finitef128 (_Float128 __value) __attribute__ ((__nothrow__ )) __attribute__ ((__const__));

  This declaration itself is OK.  The problem arises when include/math.h
  creates the hidden prototype ('hidden_proto (__finitef128)'), which
  expands to:

    extern __typeof (__finitef128) __finitef128 __attribute__ ((visibility ("hidden")));

  Since __finitef128 is not declared, __typeof fails.  This effect was
  already true for the 'float' and 'long double' versions and is now true
  for float128.  Likewise for isinsff128 and isnanf128.

>> +/* The following definitions, although not related to the 'double'
>> +   version of 'finite', are required to compensate for the unintended
>> +   macro expansion of __finitef to __redirect___finitef, etc. in
>> +   math/bits/mathcalls-helper-functions.h.  */  
>
>Likewise.
>I suggest the following change:
>
>/* The following definitions, although not related to the 'double'
>   version of 'finite', are required to guarantee the macro expansion
>   of __finitef to __redirect___finitef, etc. in
>   math/bits/mathcalls-helper-functions.h and include/math.h.  */

The expansion in mathcalls-helper-functions.h is unintended, but we need
to guarantee the same expansion in include/math.h, so what about the
following:

  The following definitions, although not related to the 'double' version
  of 'finite', are required to guarantee expansions (e.g.: from __finitef
  to __redirect_finitef) in include/math.h, thus compensating for the
  unintended macro expansions in math/bits/mathcalls-helper-functions.h.


OK with these changes?