Re: [avr-libc-dev] selective linking of floating point support for *printf / *scanf

[Andrew Haley]

On 09/02/2014 08:33 AM, Joey Ye wrote:
> On Sat, Aug 30, 2014 at 12:26 PM, Thomas Preud'homme
> <address@hidden> wrote:
>>> From: Grissiom [mailto:address@hidden
>>> Sent: Friday, August 29, 2014 11:51 PM
>>>
>>> Yes, it does.  The namespace reserved for the implementation is _[_A-Z].
>>  > The namespace _[a-z] is still available for the user.  Which means the
>>> user can declare their own _printf_float, and WE (as the implementation)
>>> MUST NOT INTERFERE with it.  Since WE are the implementation, we should
>>> use the namespace reserved for us, namely __printf_float.
>>
>> Mmmh indeed. I checked C99 and section 7.1.3 paragraph 1 third clause states:
>>
>> "All identifiers that begin with an underscore and either an uppercase 
>> letter or
>> another underscore are always reserved for any use."
>>
>> Next clause express how single underscore not followed by a capital letter is
>> reserved:
>>
>> "All identifiers that begin with an underscore are always reserved for use 
>> as identifiers
>> with file scope in both the ordinary and tag name spaces."
>
> Apparently newlib is not following this specification very well, as
> there are symbols like _abc_r defined every where in current newlib.

newlib is part of the implementation, so it's allowed to do this.

Andrew.