From 655ba783f8b2c9a8c3f4edb45e6db468aca22188 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Tue, 17 Jan 2017 18:03:35 +0100
Subject: Defer set-to-zero in triangular = product so that no aliasing issue
 occur in the common:   A.triangularView() = B*A.sefladjointView()*B.adjoint()
 case that used to work in 3.2.

---
 test/product_mmtr.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'test/product_mmtr.cpp')

diff --git a/test/product_mmtr.cpp b/test/product_mmtr.cpp
index b66529acd..f6e4bb1ae 100644
--- a/test/product_mmtr.cpp
+++ b/test/product_mmtr.cpp
@@ -62,6 +62,19 @@ template<typename Scalar> void mmtr(int size)
   CHECK_MMTR(matc, Upper, -= (s*sqc).template triangularView<Upper>()*sqc);
   CHECK_MMTR(matc, Lower, = (s*sqr).template triangularView<Lower>()*sqc);
   CHECK_MMTR(matc, Upper, += (s*sqc).template triangularView<Lower>()*sqc);
+
+  // check aliasing
+  ref2 = ref1 = matc;
+  ref1 = sqc.adjoint() * matc * sqc;
+  ref2.template triangularView<Upper>() = ref1.template triangularView<Upper>();
+  matc.template triangularView<Upper>() = sqc.adjoint() * matc * sqc;
+  VERIFY_IS_APPROX(matc, ref2);
+
+  ref2 = ref1 = matc;
+  ref1 = sqc * matc * sqc.adjoint();
+  ref2.template triangularView<Lower>() = ref1.template triangularView<Lower>();
+  matc.template triangularView<Lower>() = sqc * matc * sqc.adjoint();
+  VERIFY_IS_APPROX(matc, ref2);
 }
 
 void test_product_mmtr()
-- 
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