From e02f67eff704648b31de86efeef4f620c3af03a1 Mon Sep 17 00:00:00 2001
From: sneaxiy <sneaxiy@126.com>
Date: Mon, 24 Dec 2018 10:02:08 +0000
Subject: [PATCH] rewrite unsafe_cast test=develop

---
 paddle/fluid/framework/ddim.cc | 4 ----
 paddle/fluid/framework/ddim.h  | 4 +++-
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/paddle/fluid/framework/ddim.cc b/paddle/fluid/framework/ddim.cc
index 37544e97eb6..e7a6df57e53 100644
--- a/paddle/fluid/framework/ddim.cc
+++ b/paddle/fluid/framework/ddim.cc
@@ -131,8 +131,6 @@ DDim slice_ddim(const DDim& dim, int begin, int end) {
 
 int arity(const DDim& d) { return d.size(); }
 
-/// \cond HIDDEN
-
 struct DDimPrinter {
   std::ostream& os;
   explicit DDimPrinter(std::ostream& os_) : os(os_) {}
@@ -143,8 +141,6 @@ struct DDimPrinter {
   }
 };
 
-/// \endcond
-
 std::ostream& operator<<(std::ostream& os, const DDim& ddim) {
   ddim.apply_visitor(DDimPrinter(os));
   return os;
diff --git a/paddle/fluid/framework/ddim.h b/paddle/fluid/framework/ddim.h
index 452072a5876..295d09bbcac 100644
--- a/paddle/fluid/framework/ddim.h
+++ b/paddle/fluid/framework/ddim.h
@@ -126,7 +126,9 @@ class DDim {
  private:
   template <int D>
   inline Dim<D>& UnsafeCast() {
-    return const_cast<Dim<D>&>(const_cast<const DDim*>(this)->UnsafeCast<D>());
+    static_assert(D >= 0 && D <= kMaxRank, "Invalid rank");
+    auto* p = static_cast<void*>(&dim_);
+    return *reinterpret_cast<Dim<D>*>(p);
   }
 
   template <int D>
-- 
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