From 25a27f124a133d85b934f13faa1642e3c63dc9df Mon Sep 17 00:00:00 2001 From: Matthias Maier Date: Mon, 16 May 2022 23:29:57 -0500 Subject: [PATCH] Step-75: use well-formed deleter LLVM/Clang's libc++ library version 13/14 got stricter by checking requirements of the deleter, in particular, according to [1] a deleter must pass the requirement `__shared_ptr_deleter_ctor_reqs` which is defined as follows: ``` template ()(declval<_Pt>()))> static true_type __well_formed_deleter_test(int); template static false_type __well_formed_deleter_test(...); template struct __well_formed_deleter : decltype(__well_formed_deleter_test<_Dp, _Pt>(0)) {}; template struct __shared_ptr_deleter_ctor_reqs { static const bool value = __compatible_with<_Tp, _Yp>::value && is_move_constructible<_Dp>::value && __well_formed_deleter<_Dp, _Tp*>::value; }; ``` Unfortunately, our construct ``` coarse_grid_triangulations.emplace_back( const_cast *>(&(dof_handler.get_triangulation())), [](auto &) {}); ``` does not pass this test. The issue is that the deleter takes a pointer, not a reference which, so the lambda `[](auto &){}` does not pass above `__shared_ptr_deleter_ctor_reqs`. While at it, remove the const cast: `coarse_grid_triangulations` is declared as a vector holding a `shared_ptr>`, thus we should simply take the address and not convert to a non-const object. [1] https://github.com/llvm/llvm-project/blob/main/libcxx/include/__memory/shared_ptr.h --- examples/step-75/step-75.cc | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/examples/step-75/step-75.cc b/examples/step-75/step-75.cc index d59ee52a60..ef467db930 100644 --- a/examples/step-75/step-75.cc +++ b/examples/step-75/step-75.cc @@ -669,8 +669,7 @@ namespace Step75 dof_handler.get_triangulation()); else coarse_grid_triangulations.emplace_back( - const_cast *>(&(dof_handler.get_triangulation())), - [](auto &) {}); + &(dof_handler.get_triangulation()), [](auto *) {}); // Determine the total number of levels for the multigrid operation and // allocate sufficient memory for all levels. -- 2.39.5