Perhaps I don't. The fact is that my guile 1.8 subformula was pretty much identical with the standalone guile 1.8 formula found in the taps, yet the logs clearly indicated that the subformula was building with different compiler flags before actually failing. This could perhaps be because superenv did not, I believe, have any effect on the subformula, whereas it did seem to kick in in the formula. Is this a reasonable theory? It's been some time, and I'm reluctant to uninstall this 2hr build being in the middle of actual work with LilyPond.