C: Fix a bug where function argument type becomes more specific due to flow typing

Added a regression test as c/test/downcast_fn.sail

2 files changed, 24 insertions, 0 deletions

diff --git a/test/c/downcast_fn.expect b/test/c/downcast_fn.expect
new file mode 100644
index 00000000..9766475a
--- /dev/null
+++ b/test/c/downcast_fn.expect
@@ -0,0 +1 @@
+ok
diff --git a/test/c/downcast_fn.sail b/test/c/downcast_fn.sail
new file mode 100644
index 00000000..d4b8ae5d
--- /dev/null
+++ b/test/c/downcast_fn.sail
@@ -0,0 +1,23 @@
+default Order dec
+
+$include <flow.sail>
+
+val f1 : forall 'n, 0 < 'n <= 8. int('n) -> unit
+
+function f1(_) = ()
+
+val f2 : forall 'n, 'n > 0. int('n) -> unit
+
+function f2(width) =
+  if 'n <= 8 then
+    f1(width)
+  else ()
+
+val "print" : string -> unit
+
+val main : unit -> unit
+
+function main() = {
+  f2(3);
+  print("ok\n")
+}