D-Programming-Language/phobos — pull request #2071 by monarchdodra (2014-04-06 17:37:44+00:00)
Title: Fix Issue 12434 - std.algorithm.sum of immutable array too

https://d.puremagic.com/issues/show_bug.cgi?id=12434

Simply uses the inference's `Unqual` type as a seed, rather than the straight up result.

Also add some unittesting while at it.