updates Subspace to work with Clang 21

1. Updates submodules to near-ToT
   * third_party/buildtools: edbefce..efa06a1
   * third_party/fmt:        757564f5..c7925241
   * third_party/googletest: ec25eea8..155b337c
   * third_party/nanobench:  a5a50c2..e432789
2. Clang seems to have tightened up where lifetimebound annotations go:
   it looks like they need to go after the name is declared, rather than
   after the declaration is complete.
3. Suppresses some new errors (see comments for why).

Fixes #464

Author: cjdb

sus/collections/slice.h

@@ -164,7 +164,7 @@ class [[_sus_trivial_abi]] Slice final {
   /// #[doc.overloads=from.array]
   template <size_t N>
     requires(N <= ::sus::cast<usize>(isize::MAX))
-  _sus_pure static constexpr Slice from(const T (&data)[N] sus_lifetimebound) {
+  _sus_pure static constexpr Slice from(const T (&data sus_lifetimebound)[N]) {
     // We strip the `const` off `data`, however only const access is provided
     // through this class. This is done so that mutable types can compose Slice
     // and store a mutable pointer.
@@ -383,7 +383,7 @@ class [[_sus_trivial_abi]] SliceMut final {
   /// #[doc.overloads=from.array]
   template <size_t N>
     requires(N <= ::sus::cast<usize>(isize::MAX_PRIMITIVE))
-  _sus_pure static constexpr SliceMut from(T (&data)[N] sus_lifetimebound) {
+  _sus_pure static constexpr SliceMut from(T (&data sus_lifetimebound)[N]) {
     return SliceMut(::sus::iter::IterRefCounter::empty_for_view(), data, N);
   }
 

sus/ptr/copy.h

@@ -79,9 +79,12 @@ void copy_nonoverlapping(::sus::marker::UnsafeFnMarker, const T* src, T* dst,
                   (dst < src && dst <= src - count.primitive_value));
   if constexpr (::sus::mem::size_of<T>() > 1) {
     auto bytes = count.checked_mul(::sus::mem::size_of<T>()).expect("overflow");
-    memcpy(dst, src, bytes);
+    // Clang isn't able to detect that `T` is trivially relocatable, and errors
+    // out when it's not trivially copyable. We cast to `void*` since we are
+    // certain that it's trivially relocatable.
+    memcpy(static_cast<void*>(dst), src, bytes);
   } else {
-    memcpy(dst, src, count);
+    memcpy(static_cast<void*>(dst), src, count);
   }
 }
 

sus/ptr/nonnull.h

@@ -197,7 +197,9 @@ struct fmt::formatter<::sus::ptr::NonNull<T>, Char> {
   template <class FormatContext>
   constexpr auto format(const ::sus::ptr::NonNull<T>& t,
                         FormatContext& ctx) const {
-    return underlying_.format(t.as_ptr(), ctx);
+    // t.as_ptr() returns `const T*`, so we need to cast its constness away in
+    // order to format it.
+    return underlying_.format(const_cast<T*>(t.as_ptr()), ctx);
   }
 
  private: