This invocation of rdmd:
rdmd --eval '"hi".all!isWhite'
yields this error message:
/usr/include/dmd/phobos/std/algorithm/searching.d(125): Error: static assert: "sWhit isn't a unary predicate function for range.front"
which complains about 'sWhit' instead of 'isWhite'.
This happens due to
static assert(is(typeof(unaryFun!pred(range.front))),
"`" ~ pred.stringof[1..$-1] ~ "` isn't a unary predicate function for range.front");
which assumes that pred is a string whose .stringof needs to be stripped of double quotes.