git: cb80698e4c85 - stable/13 - Reapply: <type_traits>: Avoid instantiating a pointer type in std::decay<>

The branch stable/13 has been updated by dim:

URL: https://cgit.FreeBSD.org/src/commit/?id=cb80698e4c850fbe6f13f4f937501c5639ecfca5

commit cb80698e4c850fbe6f13f4f937501c5639ecfca5
Author:     Dimitry Andric <dim@FreeBSD.org>
AuthorDate: 2023-02-09 09:33:42 +0000
Commit:     Dimitry Andric <dim@FreeBSD.org>
CommitDate: 2023-04-09 14:54:53 +0000

    Reapply: <type_traits>: Avoid instantiating a pointer type in std::decay<>
    
      GCC expands the pointer type in this conditional expression even for
      template types _Up that are not arrays.  This raises an error when
      std::decay<> is used with reference types (as is done in LLVM's
      sources).  Using add_pointer<> causes GCC to only instantiate a
      pointer type for array types.
    
      A similar change to this commit (albeit reworked due to upstream
      changes) has been merged to libc++ in commit
      26068c6e60324ed866a1ca2afb5cb5eb0aaf015b.
    
      In file included from /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/__compare/ordering.h:13,
                       from /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/__compare/common_comparison_category.h:12,
                       from /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/tuple:168,
                       from /usr/src/contrib/llvm-project/llvm/include/llvm/ADT/DenseMapInfo.h:20,
                       from /usr/src/contrib/llvm-project/llvm/include/llvm/ADT/DenseMap.h:17,
                       from /usr/src/contrib/llvm-project/llvm/lib/Transforms/Scalar/GVNHoist.cpp:36:
      /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/type_traits: In instantiation of 'struct std::__1::__decay<llvm::CHIArg&, true>':
      /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/type_traits:1591:89:   required from 'struct std::__1::decay<llvm::CHIArg&&>'
      /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/__utility/pair.h:132:16:   required by substitution of 'template<class _Tuple, typename std::__1::enable_if<typename std::__1::conditional<(std::__1::__tuple_like_with_size<_Tuple, 2, typename std::__1::__uncvref<_Tp>::type>::value && (! std::__1::is_same<typename std::__1::decay<_Tp>::type, std::__1::pair<llvm::BasicBlock*, llvm::SmallVector<llvm::CHIArg, 2> > >::value)), std::__1::pair<llvm::BasicBlock*, llvm::SmallVector<llvm::CHIArg, 2> >::_CheckTupleLikeConstructor, std::__1::__check_tuple_constructor_fail>::type::__enable_implicit<_Tuple>(), void>::type* <anonymous> > constexpr std::__1::pair<llvm::BasicBlock*, llvm::SmallVector<llvm::CHIArg, 2> >::pair(_Tuple&&) [with _Tuple = llvm::CHIArg&&; typename std::__1::enable_if<typename std::__1::conditional<(std::__1::__tuple_like_with_size<_Tuple, 2, typename std::__1::__uncvref<_Tp>::type>::value && (! std::__1::is_same<typename std::__1::decay<_Tp>::type, std::__1::pair<ll
 vm::BasicBlock*, llvm::SmallVector<llvm::CHIArg, 2> > >::value)), std::__1::pair<llvm::BasicBlock*, llvm::SmallVector<llvm::CHIArg, 2> >::_CheckTupleLikeConstructor, std::__1::__check_tuple_constructor_fail>::type::__enable_implicit<_Tuple>(), void>::type* <anonymous> = <missing>]'
      /usr/src/contrib/llvm-project/llvm/lib/Transforms/Scalar/GVNHoist.cpp:892:51:   required from here
      /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/type_traits:1582:30: error: forming pointer to reference type 'std::__1::remove_extent<llvm::CHIArg&>::type' {aka 'llvm::CHIArg&'}
       1582 |                      >::type type;
            |                              ^~~~
    
      Reviewed by:    dim
      Differential Revision:  https://reviews.freebsd.org/D36898
    
    This reapplies commit c36de97088a2b9141cdaf2fae2a7f41bf820ffa0, which I
    accidentally overwrote in the llvm 15 merge. (It turns out upstream did
    not merge this to their 15.x branch.)
    
    MFC after:      2 weeks
    
    (cherry picked from commit 4378cc5cfb5cf928e287c0143efb120d5558c4a0)
---
 contrib/llvm-project/libcxx/include/__type_traits/decay.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/llvm-project/libcxx/include/__type_traits/decay.h b/contrib/llvm-project/libcxx/include/__type_traits/decay.h
index d47ad03fe008..2af0c1ca42c3 100644
--- a/contrib/llvm-project/libcxx/include/__type_traits/decay.h
+++ b/contrib/llvm-project/libcxx/include/__type_traits/decay.h
@@ -37,7 +37,7 @@ public:
     typedef _LIBCPP_NODEBUG typename conditional
                      <
                          is_array<_Up>::value,
-                         typename remove_extent<_Up>::type*,
+                         typename add_pointer<typename remove_extent<_Up>::type>::type,
                          typename conditional
                          <
                               is_function<_Up>::value,