strnlen, strict ansi, newlib vs glibc

Luca Barbato
Thu Aug 14 15:31:00 GMT 2014

On 14/08/14 17:27, Joel Sherrill wrote:
> Hi
> I have some native C++ code that I developed on CentOS and it
> has no warnings. Someone moved it to Cygwin and reported warnings
> for strnlen() not being prototyped. I investigated and the program did
> include string.h. I tried RTEMS tools and got the same as Cygwin
> since we have the same string.h from newlib.
> Investigating this, it appears that strnlen() is protected by
> __STRICT_ANSI__ on newlib and  __USE_XOPEN2K8 on Linux.
> Command: g++ -Wall -std=c++0x -c
> This program is enough to reproduce the issue:
>     #include <string.h>
>     // size_t strnlen( const char *, size_t );
>     size_t f( const char *str )
>     {
>       return strnlen( str, 1000 );
>     }
> What do you all think?

It is a known issue with newlib headers.

They mistakenly assume __STRICT_ANSI__ as nothing but old-C.

using -std=c99 triggers the same kind of issues.

The common way to solve it is adding -U__STRICT_ANSI__


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