tree 3af82521123a8f8c55d16013f23af07123929ccf
parent efa8726ff78c4520559d360e82c997d0ce3f8e90
author Jason Rhinelander <jason@imaginary.ca> 1489722069 -0300
committer Jason Rhinelander <jason@imaginary.ca> 1489775553 -0300

Use C++17 fold expression macro

This puts the fold expressions behind the feature macro instead of a
general C++17 macro.

It also adds a fold expression optimization to constexpr_sum (guarded
by the same feature macro).