Fix #7904: update proofview env after ltac constr:()

(in case of side effects)

Also:
Fix #4781
Fix #4496

2 files changed, 109 insertions, 0 deletions

diff --git a/test-suite/bugs/closed/bug_4781.v b/test-suite/bugs/closed/bug_4781.v
new file mode 100644
index 0000000000..464a3de1b3
--- /dev/null
+++ b/test-suite/bugs/closed/bug_4781.v
@@ -0,0 +1,96 @@
+Ltac force_clear :=
+  clear;
+  repeat match goal with
+         | [ H : _ |- _ ] => clear H
+         | [ H := _ |- _ ] => clearbody H
+         end.
+
+Class abstract_term {T} (x : T) := by_abstract_term : T.
+Hint Extern 0 (@abstract_term ?T ?x) => force_clear; change T; abstract (exact x) : typeclass_instances.
+
+Goal True.
+(* These work: *)
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  pose x.
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := (eval cbv iota in (let v : T := x in v)) in
+  pose x.
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := match constr:(Set) with ?y => constr:(y) end in
+  pose x.
+(* This fails with an error: *)
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := match constr:(x) with ?y => constr:(y) end in
+  pose x. (* The command has indeed failed with message:
+Error: Variable y should be bound to a term. *)
+(* And the rest fail with Anomaly: Uncaught exception Not_found. Please report. *)
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := match constr:(x) with ?y => y end in
+  pose x.
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := (eval cbv iota in x) in
+  pose x.
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := type of x in
+  pose x. (* should succeed *)
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:(_ : abstract_term term) in
+  let x := type of x in
+  pose x. (* should succeed *)
+
+(*Apparently what [cbv iota] doesn't see can't hurt it, and [pose] is perfectly happy with abstracted lemmas only some of the time.
+
+Even stranger, consider:*)
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let y := (eval cbv iota in (let v : T := x in v)) in
+  pose y;
+    let x' := fresh "x'" in
+    pose x as x'.
+      let x := (eval cbv delta [x'] in x') in
+      pose x;
+      let z := (eval cbv iota in x) in
+      pose z.
+
+(*This works fine.  But if I change the period to a semicolon, I get:*)
+
+      let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let y := (eval cbv iota in (let v : T := x in v)) in
+  pose y;
+    let x' := fresh "x'" in
+    pose x as x';
+      let x := (eval cbv delta [x'] in x') in
+      pose x. (* Anomaly: Uncaught exception Not_found. Please report. *)
+ (* should succeed *)
+(*and if I use the second one instead of [pose x] (note that using [idtac] works fine), I get:*)
+
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let y := (eval cbv iota in (let v : T := x in v)) in
+  pose y;
+    let x' := fresh "x'" in
+    pose x as x';
+      let x := (eval cbv delta [x'] in x') in
+      let z := (eval cbv iota in x) in (* Error: Variable x should be bound to a term. *)
+      idtac. (* should succeed *)
+  exact I.
+Qed.
diff --git a/test-suite/bugs/closed/bug_7904.v b/test-suite/bugs/closed/bug_7904.v
new file mode 100644
index 0000000000..1e518e2adf
--- /dev/null
+++ b/test-suite/bugs/closed/bug_7904.v
@@ -0,0 +1,13 @@
+
+
+Class abstract_term {T} (x : T) := by_abstract_term : T.
+Hint Extern 0 (@abstract_term ?T ?x) => change T; abstract (exact x) : typeclass_instances.
+
+Goal True.
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := match constr:(x) with ?y => y end in
+  pose x as v. (* was Error: Variable x should be bound to a term but is bound to a constr. *)
+  exact v.
+Qed.