compiler errors in tests/ippl_src with clang9
Summary
Compiler errors with clang with BUILD_OPAL_UNIT_TESTS=ON
Steps to reproduce
-- The C compiler identification is Clang 9.0.1
-- The CXX compiler identification is Clang 9.0.1
-- Check for working C compiler: /opt/local/bin/mpicc-mpich-clang90
Relevant logs and/or screenshots
src/tests/ippl_src/Field/Field.cpp:1205:57: error: using integer absolute
value function 'abs' when argument is of floating point type [-Werror,-Wabsolute-value]
Vektor<unsigned,D3> N(static_cast<unsigned> (ceil( (abs(boxMin[0])+boxMax[0])/h[0])),
^
src/tests/ippl_src/Field/Field.cpp:1205:57: note: use function 'std::abs'
instead