Fixes #7779 (destruct's "in" clause was forgetting the possibility of "eqn").

This is a quick fix. Code should be made nicer along these lines:
- try to pass the name of the variable created by "mkletin_goal" in
  the monad using "refine_one";
- use a disjunctive type of "inhyps" to indicate when it is
  meaningful, rather than using [].

1 files changed, 15 insertions, 0 deletions

diff --git a/test-suite/bugs/closed/7779.v b/test-suite/bugs/closed/7779.v
new file mode 100644
index 0000000000..78936b5958
--- /dev/null
+++ b/test-suite/bugs/closed/7779.v
@@ -0,0 +1,15 @@
+(* Checking that the "in" clause takes the "eqn" clause into account *)
+
+Definition test (x: nat): {y: nat | False }. Admitted.
+
+Parameter x: nat.
+Parameter z: nat.
+
+Goal
+  proj1_sig (test x) = z ->
+  False.
+Proof.
+  intro H.
+  destruct (test x) eqn:Heqs in H.
+  change (test x = exist (fun _ : nat => False) x0 f) in Heqs. (* Check it has the expected statement *)
+Abort.