scala/scala — pull request #1543 by adriaanm (2012-10-30 21:00:38+00:00)
Title: Harden against synthetics being added more than once.

Don't add synthetic methods if they already contain synthetic
methods from the set we're about to add.

After a lot of back-and-forth, it was decided this can go in.
Development of automated tests was attempted but not feasible right now.
Manual testing will have to do.

review by @dragos (it would be interesting to document as part of the review the attempted tests and how we can improve the compiler to make this testable in the future)