If x and w are mpq_class objects, then the type of x/w is not mpq_class,
but only a proxy type that is implicitly convertible to
mpq_class. With the type deduction, CGAL::make_array(x/w, y/w,
z/w) will not create an array<mpq_class> but an array of the proxy type.
That creates the following compilation error, in a ternary operator:
- with clang:
include/CGAL/Cartesian/Vector_3.h:78:25: error: incompatible operand types ('array<__gmp_expr<[...], struct __gmp_binary_expr<class __gmp_expr<mpq_t, mpq_t>, class __gmp_expr<mpq_t, mpq_t>, struct __gmp_binary_divides>>, [...]>' and 'array<__gmp_expr<[...], __mpq_struct [1]>, [...]>')
: base( w != FT_(1) ? CGAL::make_array(x/w, y/w, z/w)
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- with g++:
include/CGAL/Cartesian/Vector_3.h:78:25: error: no match for ternary 'operator?:' (operand types are 'bool', 'std::array<__gmp_expr<__mpq_struct [1], __gmp_binary_expr<__gmp_expr<__mpq_struct [1], __mpq_struct [1]>, __gmp_expr<__mpq_struct [1], __mpq_struct [1]>, __gmp_binary_divides> >, 3ul>', and 'std::array<__gmp_expr<__mpq_struct [1], __mpq_struct [1]>, 3ul>')
: base( w != FT_(1) ? CGAL::make_array(x/w, y/w, z/w)
^
The fix is to specify the template argument of CGAL::make_array.
Laurent Rineau
6b51b12ab5