From 21a26461caf237783d93dacfad933fc6ef0fe0c0 Mon Sep 17 00:00:00 2001
From: Alasdair Armstrong
Date: Fri, 5 Apr 2019 17:03:33 +0100
Subject: Fix: Don't remove uncalled polymorphic constructors if they are
 matched upon

Previously the specialization would remove any polymorphic union
constructor that was never created anywhere in the
specification. While this wasn't usually problematic, it does leave an
edge case where such a constructor could be matched upon in a pattern,
and then the resulting match would fail to compile as it would be
matching on a constructor kind that doesn't exists.

This should fix that issue by chaging the V_ctor_kind value into an
F_ctor_kind fragment. Previously a polymorphic constructor-kind would
have been represented by its mangled name, e.g.

V_ctor_kind "zSome_unit"

would now be represented as

V_ctor_kind ("Some", unifiers, ty)

where ty is a monomorphic version of the original constructor's type
such that

ctyp_unify original_ty ty = unifiers

and the mangled name we generate is

zencode_string ("Some_" ^ string_of_list "_" string_of_ctyp unifiers)
---
 test/c/unused_poly_ctor.expect |  1 +
 test/c/unused_poly_ctor.sail   | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 test/c/unused_poly_ctor.expect
 create mode 100644 test/c/unused_poly_ctor.sail

(limited to 'test/c')

diff --git a/test/c/unused_poly_ctor.expect b/test/c/unused_poly_ctor.expect
new file mode 100644
index 00000000..e55551e8
--- /dev/null
+++ b/test/c/unused_poly_ctor.expect
@@ -0,0 +1 @@
+y = 0xFFFF
diff --git a/test/c/unused_poly_ctor.sail b/test/c/unused_poly_ctor.sail
new file mode 100644
index 00000000..c752cb33
--- /dev/null
+++ b/test/c/unused_poly_ctor.sail
@@ -0,0 +1,18 @@
+default Order dec
+
+$include <prelude.sail>
+
+val "print_endline" : string -> unit
+
+union U('a: Type) = {
+  Err : 'a,
+  Ok : bits(16)
+}
+
+function main((): unit) -> unit = {
+  let x : U(unit) = Ok(0xFFFF);
+  match x {
+    Err() => print_endline("error"),
+    Ok(y) => print_bits("y = ", y)
+  }
+}
-- 
cgit v1.2.3