Comment by tal8d

He was pretty upfront with the the possibility that his problems with rust were of his own making. The places he tried to leverage conditional compilation could be charitably described as "creative", and would raise eyebrows even in a language like C - where the preprocessor is relatively unconstrained. I'm not familiar with his project beyond the snippets he shared, so he may have had good reason to effectively ifdef inside a function call instead of any of the more traditional locations.