From: Daniel Arndt <daniel.arndt@iwr.uni-heidelberg.de>
Date: Thu, 23 Nov 2017 14:35:06 +0000 (+0100)
Subject: Avoid undefined references in AD::NumberTraits
X-Git-Tag: v9.0.0-rc1~731^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F5522%2Fhead;p=dealii.git

Avoid undefined references in AD::NumberTraits
---

diff --git a/include/deal.II/differentiation/ad/ad_number_traits.h b/include/deal.II/differentiation/ad/ad_number_traits.h
index 810b53d59f..a1a98589cc 100644
--- a/include/deal.II/differentiation/ad/ad_number_traits.h
+++ b/include/deal.II/differentiation/ad/ad_number_traits.h
@@ -836,7 +836,7 @@ namespace Differentiation
        * The number of directional derivatives that can be
        * taken with this auto-differentiable number
        */
-      static const unsigned int         n_supported_derivative_levels
+      static constexpr unsigned int     n_supported_derivative_levels
       = internal::ADNumberInfoFromEnum<
         typename internal::RemoveComplexWrapper<ScalarType>::type, ADNumberTypeCode
       >::n_supported_derivative_levels;