libcxx: update to LLVM 18

release/18.x branch, commit 78b99c73ee4b96fe9ce0e294d4632326afb2db42

This adds the flag `-D_LIBCPP_HARDENING_MODE` which is determined based
on the Zig optimization mode.

This commit also fixes libunwind, libcxx, and libcxxabi to properly
report sub compilation errors.

1 files changed, 69 insertions, 0 deletions

diff --git a/lib/libcxx/include/atomic b/lib/libcxx/include/atomic
index 2f122a707b..2e8f5b521a 100644
--- a/lib/libcxx/include/atomic
+++ b/lib/libcxx/include/atomic
@@ -262,6 +262,72 @@ struct atomic<T*>
     void notify_all() noexcept;
 };
 
+template<>
+struct atomic<floating-point-type> {  // since C++20
+  using value_type = floating-point-type;
+  using difference_type = value_type;
+
+  static constexpr bool is_always_lock_free = implementation-defined;
+  bool is_lock_free() const volatile noexcept;
+  bool is_lock_free() const noexcept;
+
+  constexpr atomic() noexcept;
+  constexpr atomic(floating-point-type) noexcept;
+  atomic(const atomic&) = delete;
+  atomic& operator=(const atomic&) = delete;
+  atomic& operator=(const atomic&) volatile = delete;
+
+  void store(floating-point-type, memory_order = memory_order::seq_cst) volatile noexcept;
+  void store(floating-point-type, memory_order = memory_order::seq_cst) noexcept;
+  floating-point-type operator=(floating-point-type) volatile noexcept;
+  floating-point-type operator=(floating-point-type) noexcept;
+  floating-point-type load(memory_order = memory_order::seq_cst) volatile noexcept;
+  floating-point-type load(memory_order = memory_order::seq_cst) noexcept;
+  operator floating-point-type() volatile noexcept;
+  operator floating-point-type() noexcept;
+
+  floating-point-type exchange(floating-point-type,
+                               memory_order = memory_order::seq_cst) volatile noexcept;
+  floating-point-type exchange(floating-point-type,
+                               memory_order = memory_order::seq_cst) noexcept;
+  bool compare_exchange_weak(floating-point-type&, floating-point-type,
+                             memory_order, memory_order) volatile noexcept;
+  bool compare_exchange_weak(floating-point-type&, floating-point-type,
+                             memory_order, memory_order) noexcept;
+  bool compare_exchange_strong(floating-point-type&, floating-point-type,
+                               memory_order, memory_order) volatile noexcept;
+  bool compare_exchange_strong(floating-point-type&, floating-point-type,
+                               memory_order, memory_order) noexcept;
+  bool compare_exchange_weak(floating-point-type&, floating-point-type,
+                             memory_order = memory_order::seq_cst) volatile noexcept;
+  bool compare_exchange_weak(floating-point-type&, floating-point-type,
+                             memory_order = memory_order::seq_cst) noexcept;
+  bool compare_exchange_strong(floating-point-type&, floating-point-type,
+                               memory_order = memory_order::seq_cst) volatile noexcept;
+  bool compare_exchange_strong(floating-point-type&, floating-point-type,
+                               memory_order = memory_order::seq_cst) noexcept;
+
+  floating-point-type fetch_add(floating-point-type,
+                                memory_order = memory_order::seq_cst) volatile noexcept;
+  floating-point-type fetch_add(floating-point-type,
+                                memory_order = memory_order::seq_cst) noexcept;
+  floating-point-type fetch_sub(floating-point-type,
+                                memory_order = memory_order::seq_cst) volatile noexcept;
+  floating-point-type fetch_sub(floating-point-type,
+                                memory_order = memory_order::seq_cst) noexcept;
+
+  floating-point-type operator+=(floating-point-type) volatile noexcept;
+  floating-point-type operator+=(floating-point-type) noexcept;
+  floating-point-type operator-=(floating-point-type) volatile noexcept;
+  floating-point-type operator-=(floating-point-type) noexcept;
+
+  void wait(floating-point-type, memory_order = memory_order::seq_cst) const volatile noexcept;
+  void wait(floating-point-type, memory_order = memory_order::seq_cst) const noexcept;
+  void notify_one() volatile noexcept;
+  void notify_one() noexcept;
+  void notify_all() volatile noexcept;
+  void notify_all() noexcept;
+};
 
 // [atomics.nonmembers], non-member functions
 template<class T>
@@ -448,6 +514,9 @@ typedef atomic<ptrdiff_t> atomic_ptrdiff_t;
 typedef atomic<intmax_t>  atomic_intmax_t;
 typedef atomic<uintmax_t> atomic_uintmax_t;
 
+typedef see-below         atomic_signed_lock_free;   // since C++20
+typedef see-below         atomic_unsigned_lock_free; // since C++20
+
 // flag type and operations
 
 typedef struct atomic_flag