This patchkit contains the remaining C/C++ frontend patches for the [[musttail]] extension that still need approval for trunk. I already committed the tree-ssa and RTL pieces.
C: I addressed Marek's feedback, but need final ack. Marek can you please take a look? C++: Fixed support for AGGR_VIEW expressions thanks to Jason's prodding. Tests: Addressed Jason's feedback and covered now hopefully all the class passing cases. I split some tests to create a full set of errors, otherwise frontend errors would stop the tree optimizers from running. The class passing tests are showing another problem in the middle-end code where implicit calls generated by the C++ frontend stop tree-tailcall early, so it can't identify the user written tail call. This results in cryptic "cannot tail-call: other reasons" fallback errors, which is not ideal, but also not a show stopper. Currently this is hidden in the test suite by running that test at -O0. -Andi