libstdc++: Add preprocessor conditions for freestanding [PR106953]

This adds checks for _GLIBCXX_HOSTED to a number of headers which are
not currently installed for freestanding, but need to be for P1642R11
support. For example, <iterator> needs to be installed for C++23
freestanding mode, but without stream iterators and streambuf iterators.
Similarly, <memory> needs to be installed, but without std::allocator
and std::shared_ptr. This change disables the non-freestanding parts of
those headers.

libstdc++-v3/ChangeLog:

	PR libstdc++/106953
	* include/backward/auto_ptr.h [!_GLIBCXX_HOSTED]: Do not define
	shared_ptr members.
	* include/bits/alloc_traits.h [!_GLIBCXX_HOSTED]: Do not declare
	std::allocator_traits<std::allocator<T>> specializations for
	freestanding.
	* include/bits/memoryfwd.h [!_GLIBCXX_HOSTED] (allocator): Do
	not declare for freestanding.
	* include/bits/stl_algo.h [!_GLIBCXX_HOSTED] (stable_partition):
	Do not define for freestanding.
	[!_GLIBCXX_HOSTED] (merge, stable_sort): Do not use temporary
	buffers for freestanding.
	* include/bits/stl_algobase.h [!_GLIBCXX_HOSTED]: Do not declare
	streambuf iterators and overloaded algorithms using them.
	* include/bits/stl_uninitialized.h [!_GLIBCXX_HOSTED]: Do not
	define specialized overloads for std::allocator.
	* include/bits/unique_ptr.h [!_GLIBCXX_HOSTED] (make_unique)
	(make_unique_for_overwrite, operator<<): Do not define for
	freestanding.
	* include/c_global/cstdlib [!_GLIBCXX_HOSTED] (_Exit): Declare.
	Use _GLIBCXX_NOTHROW instead of throw().
	* include/debug/assertions.h [!_GLIBCXX_HOSTED]: Ignore
	_GLIBCXX_DEBUG for freestanding.
	* include/debug/debug.h [!_GLIBCXX_DEBUG]: Likewise.
	* include/std/bit [!_GLIBCXX_HOSTED]: Do not use the custom
	__int_traits if <ext/numeric_traits.h> is available.
	* include/std/functional [!_GLIBCXX_HOSTED]: Do not include
	headers that aren't valid for freestanding.
	(boyer_moore_searcher, boyer_moore_horspool_searcher): Do not
	define for freestanding.
	* include/std/iterator [!_GLIBCXX_HOSTED]: Do not include
	headers that aren't valid for freestanding.
	* include/std/memory [!_GLIBCXX_HOSTED]: Likewise.
	* include/std/ranges [!_GLIBCXX_HOSTED] (istream_view): Do not
	define for freestanding.
	(views::__detail::__is_basic_string_view) [!_GLIBCXX_HOSTED]:
	Do not define partial specialization for freestanding.

1 files changed, 14 insertions, 8 deletions

diff --git a/libstdc++-v3/include/std/functional b/libstdc++-v3/include/std/functional
index 685a3e167ee..c4f75880fd8 100644
--- a/libstdc++-v3/include/std/functional
+++ b/libstdc++-v3/include/std/functional
@@ -56,18 +56,22 @@
 #include <bits/functional_hash.h>
 #include <bits/invoke.h>
 #include <bits/refwrap.h>	// std::reference_wrapper and _Mem_fn_traits
-#include <bits/std_function.h>	// std::function
-#if __cplusplus > 201402L
-# include <unordered_map>
-# include <vector>
-# include <array>
-# include <bits/stl_algo.h>
+#if _GLIBCXX_HOSTED
+# include <bits/std_function.h>	// std::function
+#endif
+#if __cplusplus >= 201703L
+# if _GLIBCXX_HOSTED
+#  include <unordered_map>
+#  include <vector>
+#  include <array>
+# endif
+# include <bits/stl_algo.h> // std::search
 #endif
 #if __cplusplus > 201703L
 # include <bits/ranges_cmp.h>
 # include <compare>
 #endif
-#if __cplusplus > 202002L
+#if __cplusplus > 202002L && _GLIBCXX_HOSTED
 # include <bits/move_only_function.h>
 #endif
 
@@ -238,7 +242,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   /**
    * @brief Trait that identifies a bind expression.
-   * 
+   *
    * Determines if the given type `_Tp` is a function object that
    * should be treated as a subexpression when evaluating calls to
    * function objects returned by `std::bind`.
@@ -1117,6 +1121,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       tuple<_ForwardIterator1, _ForwardIterator1, _BinaryPredicate> _M_m;
     };
 
+#if _GLIBCXX_HOSTED
   template<typename _Key, typename _Tp, typename _Hash, typename _Pred>
     struct __boyer_moore_map_base
     {
@@ -1359,6 +1364,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	}
       return std::make_pair(__last, __last);
     }
+#endif // HOSTED
 
 #endif // C++17
 #endif // C++14