[PATCH] Fix libstdc++-v3/include/math.h:66:1 2: error: 'constexpr bool std::isnan(double)' conflicts with a previous declaration

Gerald Pfeifer gerald@pfeifer.com
Thu Feb 4 22:11:00 GMT 2016

On Thu, 28 Jan 2016, Jonathan Wakely wrote:
> On 27/01/16 19:49 -0500, John David Anglin wrote:
>> The attached patch fixes a stage1 build error compiling genautomata.c 
>> on hpux.  We need to test for obsolete XOPEN declarations of isinf and 
>> isnan on hpux.  Further, we need to check individually for isinf and 
>> isnan on hpux11 since only isnan has an obsolete XOPEN declaration.
>> Tested on hppa2.0w-hp-hpux11.11.
> Also tests OK on x86_64-linux (with glibc 2.22).

It seems to break older versions of FreeBSD that have GCC 4.2
as their system compiler.  (Those versions aren't actually all
that old, they are stuck with GCC 4.2 as the last version under

In file included from .././../gcc-6-20160131/gcc/genautomata.c:116:0:
error: 'constexpr bool std::isinf(double)' conflicts with a previous declaration
 using std::isinf;

for a full log.


PS: I don't have direct access to this system, or I'd provide
preprocessed headers.  If you need those, I can try to create
a VM and get things reproduced there.

More information about the Libstdc++ mailing list