math.h float_t and double_t not typedef'ed when FLT_EVAL_METHOD defined

[Jeff Johnston]

I have checked in a modified version of the patch.

For implementation-defined FLT_EVAL_METHOD values, it will be assumed 
that float_t and double_t have been defined for the configuration (e.g. 
config.h or ieeefp.h).

I have removed the _FLOAT_T_DEFINED and _DOUBLE_T_DEFINED flags and the 
check in the log2f macro.  I have also defaulted float_t to float and 
double_t to double if FLT_EVAL_METHOD is not defined as was done prior 
to the patch.

In the future, I intend to remove the log2f macro and replace the log2f 
function with the BSD version which is consistent with the other log 
functions.

-- Jeff J.

On 12/17/2012 01:05 PM, Craig Howland wrote:
> Jeff or Corinna:
> Ping?  (Oddly enough, while I got my copy from the list server, I don't
> see this message in the mail archive.)
> Craig
>
>
> On 12/11/2012 05:57 PM, Craig Howland wrote:
>> Here, finally, is a patch. I have changed the approach from what I first
>> proposed to the alternative of not defining float_t and double_t when
>> FLT_EVAL_METHOD is not recognized. The reasons are explained in the
>> comments in
>> the patch.
>> The end result for the state of defining float_t and double_t will not be
>> different for Jordy's test case, but the test case will pass because
>> defining
>> log2f() as a macro is now skipped for the case.
>> Craig
>>
>> 2012-12-11 Craig Howland <howland@LGSInnovations.com>
>>
>> * libc/include/math.h: Add recognition of values 1 and 2 for
>> FLT_EVAL_METHOD; do not define log2f() macro if float_t is not defined.
>>
>>
>> On 11/16/2012 08:01 PM, Craig Howland wrote:
>>> Yes, the manner in which math.h handles float_t and double_t is
>>> lacking, and
>>> yes, the solution is quite similar to what you list. The problem is
>>> that the
>>> else case is tricky, when the value is not 0, 1, or 2.
>>>
>>> ...
>>>
>>> The two approaches for unknown values are to default to something or
>>> to define
>>> nothing. In the code below, you can see that I opted for the former,
>>> along with
>>> the reason for so doing.
>>>
>>> ...
>>>
>>> Thoughts and comments on how to handle the if? Even though I made the
>>> tentative
>>> choice of a default when I wrote this in 2010, my present inclination
>>> is that
>>> nothing should be defined so that such an implementation would have
>>> to put them
>>> in somehow for things which use them to work. (It would be less of a
>>> mess if the
>>> standard had put float_t and double_t in float.h along with
>>> FLT_EVAL_METHOD.)
>>>
>>> Craig
>>>
>>>
>>> On 11/16/2012 06:34 AM, Jordy Potman wrote:
>>>> Hi,
>>>>
>>>> I am using Newlib with a clang based compiler for our architecture.
>>>>
>>>> I think I have found an issue in Newlib's math.h.
>>>>
>>>> Newlib's math.h does not typedef float_t and double_t when
>>>> FLT_EVAL_METHOD is defined.
>>>>
>>>> math.h lines 143-147:
>>>> 143: #ifndef FLT_EVAL_METHOD
>>>> 144: #define FLT_EVAL_METHOD 0
>>>> 145: typedef float float_t;
>>>> 146: typedef double double_t;
>>>> 147: #endif /* FLT_EVAL_METHOD */
>>>>
>>>> Clang's float.h defines FLT_EVAL_METHOD (I think gcc's float.h does as
>>>> well), which I think is correct according to section 5.2.4.2.2
>>>> paragraph
>>>> 8 of the C99 standard.
>>>>
>>>> Newlib's math.h defines the log2f function as a macro which uses
>>>> float_t.
>>>>
>>>> math.h lines 354-357:
>>>> 354: extern float log2f _PARAMS((float));
>>>> 355: #if !defined(__cplusplus)
>>>> 356: #define log2f(x) (logf (x) / (float_t) _M_LN2)
>>>> 357: #endif
>>>>
>>>> This causes a compilation error if a program includes float.h before
>>>> math.h and uses the log2f function:
>>>> $ cat log2f_test.c
>>>> #include<float.h>
>>>> #include<math.h>
>>>>
>>>> float f(float a) {
>>>> return log2f(a);
>>>> }
>>>> $ xentium-clang -std=c99 -c log2f_test.c
>>>> log2f_test.c:5:10: error: use of undeclared identifier 'float_t'; did
>>>> you mean 'float'?
>>>> return log2f(a);
>>>> ^
>>>> /home/potman/opt/xentium-tools-1.0.beta9-linux64/bin/../sysroots/default/include/math.h:359:31:
>>>>
>>>>
>>>> note: expanded from
>>>> macro 'log2f'
>>>> #define log2f(x) (logf (x) / (float_t) _M_LN2)
>>>> ^
>>>> 1 error generated.
>>>>
>>>> I have changed math.h lines 354-357 to the following in our
>>>> implementation:
>>>>
>>>> #ifndef FLT_EVAL_METHOD
>>>> #define FLT_EVAL_METHOD 0
>>>> #endif /* FLT_EVAL_METHOD */
>>>> #if FLT_EVAL_METHOD == 1
>>>> typedef double float_t;
>>>> typedef double double_t;
>>>> #elif FLT_EVAL_METHOD == 2
>>>> typedef long double float_t;
>>>> typedef long double double_t;
>>>> #else
>>>> typedef float float_t;
>>>> typedef double double_t;
>>>> #endif
>>>>
>>>> This is my interpretation of how float_t and double_t should be
>>>> typedef'ed depending on the value of FLT_EVAL_METHOD as is described in
>>>> section 7.12 paragraph 2 of the C99 standard. However I am not a C99
>>>> standard expert.
>>>>
>>>> Jordy
>>>>

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