import std.regex: splitter, regex;
import std.conv: to;
import std.array: array;
void main() {
    auto s = splitter("10 30 20", r"[\s,]+".regex);
    auto r1 = s.array.to!(real[]); // OK
    auto r2 = s.to!(real[]); // Error
}


DMD 2.063.2 gives:

...\dmd2\src\phobos\std\conv.d(276): Error: template std.conv.toImpl does not match any function template declaration. Candidates are:
...\dmd2\src\phobos\std\conv.d(332):        std.conv.toImpl(T, S)(S value) if (isImplicitlyConvertible!(S, T) && !isEnumStrToStr!(S, T) && !isNullToStr!(S, T))
...\dmd2\src\phobos\std\conv.d(445):        std.conv.toImpl(T, S)(ref S s) if (isRawStaticArray!S)
...\dmd2\src\phobos\std\conv.d(461):        std.conv.toImpl(T, S)(S value) if (is(typeof(S.init.opCast!T()) : T) && !isExactSomeString!T)
...\dmd2\src\phobos\std\conv.d(492):        std.conv.toImpl(T, S)(S value) if (!isImplicitlyConvertible!(S, T) && is(T == struct) && is(typeof(T(value))))
...\dmd2\src\phobos\std\conv.d(542):        std.conv.toImpl(T, S)(S value) if (!isImplicitlyConvertible!(S, T) && is(T == class) && is(typeof(new T(value))))
...\dmd2\src\phobos\std\conv.d(276):        ... (16 more, -v to show) ...
...\dmd2\src\phobos\std\conv.d(332): Error: template std.conv.toImpl cannot deduce template function from argument types !(real[])(Splitter!(string, Regex!char))
...\dmd2\src\phobos\std\conv.d(276): Error: template instance toImpl!(real[]) errors instantiating template
test.d(7): Error: template instance std.conv.to!(real[]).to!(Splitter!(string, Regex!char)) error instantiating