From 22bf4efd61b916abc81e41bbe70428e534dd0013 Mon Sep 17 00:00:00 2001
From: charguer
Date: Tue, 19 Dec 2017 16:13:35 +0100
Subject: allow Prop as source for coercions

---
 test-suite/success/coercions.v | 25 +++++++++++++++++++++++++
 vernac/class.ml                |  2 +-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/test-suite/success/coercions.v b/test-suite/success/coercions.v
index 9b11bc011c..d4fa132d17 100644
--- a/test-suite/success/coercions.v
+++ b/test-suite/success/coercions.v
@@ -131,3 +131,28 @@ Local Coercion l2v2 : list >-> vect.
 Fail Check (fun l : list (T1 * T1) => (l : vect _ _)).
 Check (fun l : list (T1 * T1) => (l2v2 l : vect _ _)).
 Section what_we_could_do.
+
+
+(** Unit test for Prop as source class *)
+
+Module TestPropAsSourceCoercion.
+
+  Parameter heap : Prop.
+
+  Parameter heap_empty : heap.
+
+  Definition hprop := heap -> Prop.
+
+  Coercion hpure (P:Prop) : hprop := fun h => h = heap_empty /\ P.
+
+  Parameter heap_single : nat -> nat -> hprop.
+
+  Parameter hstar : hprop -> hprop -> hprop.
+
+  Notation "H1 \* H2" := (hstar H1 H2) (at level 69).
+
+  Definition test := heap_single 4 5 \* (5 <> 4) \* heap_single 2 4 \* (True).
+
+  (* Print test. -- reveals [hpure] coercions *)
+
+End TestPropAsSourceCoercion.
\ No newline at end of file
diff --git a/vernac/class.ml b/vernac/class.ml
index cc676af1b4..59d9331087 100644
--- a/vernac/class.ml
+++ b/vernac/class.ml
@@ -225,7 +225,7 @@ let build_id_coercion idf_opt source poly =
   ConstRef kn
 
 let check_source = function
-| Some (CL_FUN|CL_SORT as s) -> raise (CoercionError (ForbiddenSourceClass s))
+| Some (CL_FUN as s) -> raise (CoercionError (ForbiddenSourceClass s))
 | _ -> ()
 
 (*
-- 
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