From 024cf5ae087024399cc894b121437d72cd11b480 Mon Sep 17 00:00:00 2001
From: Pierre-Marie Pédrot
Date: Fri, 30 Sep 2016 16:42:54 +0200
Subject: Fix bug #4471: [generalize dependent] permits ill-typed terms in
 trunk.

This bug was introduced by 37ab45726, because the new apply_type function
was not checking that the new goal was indeed well-typed. We add this check
locally in the generalize dependent tactic.
---
 tactics/tactics.ml            | 2 ++
 test-suite/bugs/closed/4471.v | 6 ++++++
 2 files changed, 8 insertions(+)
 create mode 100644 test-suite/bugs/closed/4471.v

diff --git a/tactics/tactics.ml b/tactics/tactics.ml
index 2d901c2dbc..2fe8e0bc34 100644
--- a/tactics/tactics.ml
+++ b/tactics/tactics.ml
@@ -2807,6 +2807,8 @@ let old_generalize_dep ?(with_let=false) c gl =
   in
   let cl'',evd = generalize_goal gl 0 ((AllOccurrences,c,body),Anonymous)
     (cl',project gl) in
+  (** Check that the generalization is indeed well-typed *)
+  let (evd, _) = Typing.type_of env evd cl'' in
   let args = Context.Named.to_instance to_quantify_rev in
   tclTHENLIST
     [tclEVARS evd;
diff --git a/test-suite/bugs/closed/4471.v b/test-suite/bugs/closed/4471.v
new file mode 100644
index 0000000000..36efc42d47
--- /dev/null
+++ b/test-suite/bugs/closed/4471.v
@@ -0,0 +1,6 @@
+Goal forall (A B : Type) (P : forall _ : prod A B, Type) (a : A) (b : B) (p p0 : forall (x : A) (x' : B), P (@pair A B x x')),
+    @eq (P (@pair A B a b)) (p (@fst A B (@pair A B a b)) (@snd A B (@pair A B a b)))
+        (p0 (@fst A B (@pair A B a b)) (@snd A B (@pair A B a b))).
+Proof.
+  intros.
+  Fail generalize dependent (a, b).
-- 
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