From 301d13755a3fd0829aafcb6db3eb98f0b31216ba Mon Sep 17 00:00:00 2001 From: Max Kahnt <max.kahnt@fu-berlin.de> Date: Thu, 28 Sep 2017 17:02:59 +0200 Subject: [PATCH] Workaround for enable_if not providing a type... ... when it does not depend on the function template parameter (experienced with clang). --- dune/matrix-vector/genericvectortools.hh | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/dune/matrix-vector/genericvectortools.hh b/dune/matrix-vector/genericvectortools.hh index 9c15e8a..ed8ac89 100644 --- a/dune/matrix-vector/genericvectortools.hh +++ b/dune/matrix-vector/genericvectortools.hh @@ -183,18 +183,20 @@ protected: /// Note: We use PriorityTags to enforce trial order w.r.t. failure fallback. /// Additionally we use it to circumvent ambiguous overloading. /// Call subSizeProvider without PriorityTag via the priority tag forward helper for standard behaviour. + /// We use AlwaysTrue to silence errors about enable_if not providing a type when it does not depend + /// on the function template parameter. // ... from a sparse/dynamic matrix - template <class SizeProviderRow, typename = std::enable_if_t<isMatrix<Vector>() and not isTupleOrDerived<Vector>()>> + template <class SizeProviderRow, typename = std::enable_if_t<isMatrix<Vector>() and not isTupleOrDerived<Vector>() and AlwaysTrue<SizeProviderRow>::value>> static decltype(auto) subSizeProvider(SizeProviderRow&& row, PriorityTag<21>) { return *row.begin(); } // .. from a tuple like/static matrix - template <class SizeProviderRow, typename = std::enable_if_t<isMatrix<Vector>() and isTupleOrDerived<Vector>()>> + template <class SizeProviderRow, typename = std::enable_if_t<isMatrix<Vector>() and isTupleOrDerived<Vector>() and AlwaysTrue<SizeProviderRow>::value>> static decltype(auto) subSizeProvider(SizeProviderRow&& row, PriorityTag<20>) { return row[Indices::_0]; } // ... from a vector - template <class SizeProviderRow, typename = std::enable_if_t<isVector<Vector>()>> + template <class SizeProviderRow, typename = std::enable_if_t<isVector<Vector>() and AlwaysTrue<SizeProviderRow>::value>> static decltype(auto) subSizeProvider(SizeProviderRow&& row, PriorityTag<10>) { return row; } -- GitLab