fix: elim/v handles eliminator from Derive Inversion (issue #2)

Also:
- fix elim trying to saturate too much and not raising the expected exn
- fix fill_occ_pattern when occ is {-}, it used to lose the
  instantiation obtained by matching the term

1 files changed, 19 insertions, 0 deletions

diff --git a/mathcomp/ssrtest/derive_inversion.v b/mathcomp/ssrtest/derive_inversion.v
new file mode 100644
index 0000000..71257d8
--- /dev/null
+++ b/mathcomp/ssrtest/derive_inversion.v
@@ -0,0 +1,19 @@
+Require Import ssreflect ssrbool.
+
+Set Implicit Arguments.
+
+  Inductive wf T : bool -> option T -> Type :=
+  | wf_f : wf false None
+  | wf_t : forall x, wf true (Some x).
+
+  Derive Inversion wf_inv with (forall T b (o : option T), wf b o) Sort Prop.
+
+  Lemma Problem T b (o : option T) :
+    wf b o ->
+    match b with
+    | true  => exists x, o = Some x
+    | false => o = None
+    end.
+  Proof.
+  by case: b; elim/wf_inv=>//;case: o=>// a *; exists a.
+  Qed.