g++ 6 abs() issue

[Orion Poplawski]

Apparently g++ 6 does not define abs() for unsigned types, so you end up 
with errors like:

corefcn/pr-output.cc: In instantiation of 'void 
octave_print_internal_template(std::ostream&, const intNDArray<T>&, 
bool, int) [with T = octave_int<signed char>; std::ostream = 
std::basic_ostream<char>]':
corefcn/pr-output.cc:3385:200:   required from here
corefcn/pr-output.cc:3261:54: error: call of overloaded 'abs(signed 
char)' is ambiguous
                   (gnulib::floor (log10 (double (abs (nda(i).value 
()))) + 1.0));
                                                  ~~~~^~~~~~~~~~~~~~~~~

See https://gcc.gnu.org/gcc-6/porting_to.html

No idea how to best handle this.

--
Orion Poplawski
Technical Manager                     303-415-9701 x222
NWRA/CoRA Division                    FAX: 303-415-9702
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