Bug 20351 – Unknown error, should actually be: pure function cannot call impure function

``` import std.format : formattedWrite; import std.typecons : Nullable; struct GS { BS bs; static int gTD() { static Nullable!GS ltd; return 0; } } struct BS { void toString(T)(T sink) const { sink.formattedWrite!"%s"(c()); } } static immutable uint d; struct C(T) { void toString(F)(F sink) const { import std.format : formattedWrite; sink.formattedWrite!"%s"(1.0); } void __toString() pure { import std.array : Appender; auto buf = new Appender!(char[]); toString(buf); } } auto c()() { return C!(double)(); } ``` The real error here is that C!double.__toString() can't call impure function C!double.toString().

Hmm, I cannot reproduce this. The code seems to compile.