Revert C++17

CMakeLists.txt

@@ -20,7 +20,7 @@ project(BornAgain
      # TODO modernize FindCerf to get rid of AssertLibraryFunction to restore restriction to CXX
 
 set(CMAKE_C_STANDARD 11)
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 14)
 
 include(CTest) # equivalent to "enable_testing() ???
 add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND} -LE Fullcheck)

Core/Multilayer/SpecularMagneticStrategy.cpp

@@ -194,7 +194,9 @@ void SpecularMagneticStrategy::propagateBackwardsForwards(
         coeff[i].m_w_min = l * coeff[i + 1].m_w_min;
 
         // rotate and normalize polarization
-        const auto [S, norm] = findNormalizationCoefficients(coeff[i]);
+        const auto Snorm = findNormalizationCoefficients(coeff[i]);
+        auto S = Snorm.first;
+        auto norm = Snorm.second;
 
         SMatrices[i] = S;
         Normalization[i] = norm;