[Nix-dev] $out in configureFlags is not expanded

[Peter Simons]

Hi Lluís,

 >> Maybe it would be sufficient to document the current behavior in
 >> more detail?
 >
 > Many people hit this problem, when they started using mkDerivation.

yes, that is true. I'm just not convinced that changing the semantics of
configureFlags is the best solution for this issue. IMHO, documentation
can improve the status quo, too, without requiring an intrusive change
to the default builder.


 > Can you describe what breaking cases you have in mind with that 'eval'?

For example:

  configureFlags = "--whoami-expression=$USER";

  configureFlags = "--initial-array=( 'state 1' 'state 5' )";

Please don't get me wrong, though: I know that all of those problems can
be addressed in one way or another, and we probably don't have many
packages that use such pathological constructs. Still, I'm just not
convinced that the issue is significant enough to warrant a change to
the default builder.

Take care,
Peter