From b1cb26eed7bdde340aeacf23e1bc461eb06c4ddd Mon Sep 17 00:00:00 2001
From: Emilio Jesus Gallego Arias
Date: Sat, 7 Nov 2020 23:14:53 +0100
Subject: [obligation] Proper handle no obligations on `Next Obligation`

Fixes #13320 .

Trivial programming error, actually this is handled better in a
further refactoring branch not submitted due to the long time the
whole rework took.
---
 test-suite/output/bug_13320.out | 2 ++
 test-suite/output/bug_13320.v   | 2 ++
 vernac/declare.ml               | 7 ++++++-
 3 files changed, 10 insertions(+), 1 deletion(-)
 create mode 100644 test-suite/output/bug_13320.out
 create mode 100644 test-suite/output/bug_13320.v

diff --git a/test-suite/output/bug_13320.out b/test-suite/output/bug_13320.out
new file mode 100644
index 0000000000..97efe1da87
--- /dev/null
+++ b/test-suite/output/bug_13320.out
@@ -0,0 +1,2 @@
+The command has indeed failed with message:
+No obligations remaining
diff --git a/test-suite/output/bug_13320.v b/test-suite/output/bug_13320.v
new file mode 100644
index 0000000000..6f3c51bbe7
--- /dev/null
+++ b/test-suite/output/bug_13320.v
@@ -0,0 +1,2 @@
+(* Next Obligation should fail normally, not with an anomaly. *)
+Fail Next Obligation.
diff --git a/vernac/declare.ml b/vernac/declare.ml
index 0baae6eca5..367d0bf944 100644
--- a/vernac/declare.ml
+++ b/vernac/declare.ml
@@ -2499,7 +2499,12 @@ let admit_obligations ~pm n =
 
 let next_obligation ~pm n tac =
   let prg = match n with
-    | None -> State.first_pending pm |> Option.get
+    | None ->
+      begin match State.first_pending pm with
+        | Some prg -> prg
+        | None ->
+          Error.no_obligations None
+      end
     | Some _ -> get_unique_prog ~pm n
   in
   let {obls; remaining} = Internal.get_obligations prg in
-- 
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