From e91a8c8659d08178dfec45a06529ade208ded186 Mon Sep 17 00:00:00 2001
From: Alasdair Armstrong
Date: Mon, 26 Feb 2018 16:08:32 +0000
Subject: Fix missing case in pattern completeness check

Fixes #4
---
 src/pattern_completeness.ml               |  3 +--
 test/typecheck/pass/pat_completeness.sail | 11 +++++++++++
 2 files changed, 12 insertions(+), 2 deletions(-)
 create mode 100644 test/typecheck/pass/pat_completeness.sail

diff --git a/src/pattern_completeness.ml b/src/pattern_completeness.ml
index ebb402e5..94623e6f 100644
--- a/src/pattern_completeness.ml
+++ b/src/pattern_completeness.ml
@@ -232,8 +232,7 @@ let rec join ctx gpat1 gpat2 =
        | None, None -> None
        | Some args1, None -> Some args1
        | None, Some args2 -> Some args2
-       | Some args1, Some args2 ->
-          assert false
+       | Some args1, Some args2 -> Some (join ctx args1 args2)
      in
      let ctors = Bindings.merge ctor_merge ctors1 ctors2 in
      if Bindings.for_all (fun _ gpat -> is_wild gpat) ctors then
diff --git a/test/typecheck/pass/pat_completeness.sail b/test/typecheck/pass/pat_completeness.sail
new file mode 100644
index 00000000..fd4a7757
--- /dev/null
+++ b/test/typecheck/pass/pat_completeness.sail
@@ -0,0 +1,11 @@
+union option ('a : Type) = {None, Some : 'a}
+
+union ast = {Foo : unit}
+
+let x : option(ast) = Some(Foo)
+
+let y : unit = match(x) {
+  Some(Foo) => (),
+  Some(a)   => (),
+  None      => ()
+}
\ No newline at end of file
-- 
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