Below code snippet is from std.metastrings: string s=Format!("Arg %s=%s","foo",27); writefln(s);// "Arg foo = 27" can't compile,error msg: testFormat.d(30): Error: cannot implicitly convert expression ("Arg %s=%sfoo27") of type const(char[]) to immutable(char)[] Not sure whether this is a bug.
Fixed a while ago.