From 760f2e15ce8a29e6e6895d02befc047b84b29ac7 Mon Sep 17 00:00:00 2001
From: Soonho Kong <soonhok@cs.cmu.edu>
Date: Tue, 1 Oct 2013 16:45:36 -0700
Subject: [PATCH] feat(library/replace_using_ctx): add static_assert

---
 src/library/replace_using_ctx.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/library/replace_using_ctx.h b/src/library/replace_using_ctx.h
index db3f6931b..246f68b86 100644
--- a/src/library/replace_using_ctx.h
+++ b/src/library/replace_using_ctx.h
@@ -26,6 +26,10 @@ template<typename F, typename P = default_replace_postprocessor>
 class replace_using_ctx_fn {
     static_assert(std::is_same<typename std::result_of<F(expr const &, context const &, unsigned)>::type, expr>::value,
                   "replace_using_ctx_fn: return type of F is not expr");
+    // the return type of P()(e1, e2) should be void
+    static_assert(std::is_same<typename std::result_of<decltype(std::declval<P>())(expr const &, expr const &)>::type,
+                  void>::value,
+                  "The return type of P()(e1, e2) is not void");
     typedef scoped_map<expr, expr, expr_hash, expr_eqp> cache;
     cache                      m_cache;
     F                          m_f;