- The error messages were wrong: the goal needs to be absorbing, not the hypothesis.
- The wrong failure number was used in `iAssumption`, which caused the error not
  to be propagated properly.

Gregory Malecha authored 5 years ago and Robbert Krebbers committed 5 years ago

- remove "odd" comment
- move atomic triples to bi_scope

Paolo G. Giarrusso authored 5 years ago and Robbert Krebbers committed 5 years ago

When proving `foo` through a fixpoint, Coq's guardedness checker needs to see to
which arguments `foo` is applied. Opaque lemmas applied to `foo` itself prevent
that, so make them transparent.
* Make `IntoEmpValid` lemmas transparent.
* Expose application of `IntoEmpValid` instance to its argument.
* Add comment to `tac_pose_proof`

This MR brings back the type of `tac_pose_proof` to the one it had before !329.
Hence, this seems worth a comment.

This test case arose in Iron.

Also, rewrite `iIntoEmpValid`. Now, instead of using Ltac to traverse
the type of the term and generate goals for the premises, we repeatedly
apply a series of lemmas. This has the advantage that it works up to
convertability, and we no longer need the `eval ...` hacks.

Fix issue pointed out by @tchajed in !330 (comment 41322)