Found the following significant warnings:
  ../src/s2/util/coding/coder.h:161:44: warning: 'exchange<char *, char *>' is deprecated [-Wdeprecated-declarations]
  ../src/s2/util/coding/coder.h:493:23: warning: 'is_trivially_copy_constructible' is deprecated [-Wdeprecated-declarations]
  ../src/s2/util/coding/coder.h:495:23: warning: 'is_trivially_copy_assignable' is deprecated [-Wdeprecated-declarations]
  ../src/s2/util/coding/coder.h:497:23: warning: 'is_trivially_destructible' is deprecated [-Wdeprecated-declarations]
  ../src/s2/util/math/vector.h:62:34: warning: 'make_index_sequence' is deprecated: Use std::make_index_sequence instead. [-Wdeprecated-declarations]
  ../src/s2/util/math/vector.h:70:31: warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  ../src/s2/util/math/vector.h:311:53: warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  ../src/s2/util/math/vector.h:317:46: warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  ../src/s2/util/math/vector.h:322:47: warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  ../src/s2/util/math/vector.h:327:38: warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  ../src/s2/util/math/vector.h:332:38: warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  /usr/local/clang/include/absl/log/internal/check_impl.h../src/s2/util/math/vector.h::51327::338::  note: warning: expanded from macro 'ABSL_LOG_INTERNAL_CHECK_NE_IMPL''index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  332:38: warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  ../src/s2/util/gtl/compact_array.h:523:23: warning: 'is_trivially_copy_constructible' is deprecated [-Wdeprecated-declarations]
  ../src/s2/util/gtl/compact_array.h:524:23: warning: 'is_trivially_copy_assignable' is deprecated [-Wdeprecated-declarations]
  ../src/s2/util/gtl/compact_array.h:525:23: warning: 'is_trivially_destructible' is deprecated [-Wdeprecated-declarations]
  ../src/s2/util/gtl/compact_array.h:362:16: warning: 'is_trivially_default_constructible' is deprecated [-Wdeprecated-declarations]
  ../src/s2/s2cell_iterator.h:89:3: warning: 'decay_t' is deprecated [-Wdeprecated-declarations]
  53: warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]In file included from 
  /usr/local/clang/include/absl/container/internal/btree_container.h../src/s2/util/math/vector.h::496322::947::  note: warning: macro 'ABSL_INTERNAL_X' defined here'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  :3: warning:   'decay_t' is deprecated [-Wdeprecated-declarations]801
  /usr/local/clang/include/absl/container/internal/raw_hash_map.h../src/s2/util/math/vector.h::120317::946::  note: warning: macro 'ABSL_INTERNAL_X' defined here'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  :16: warning: 'is_trivially_default_constructible' is deprecated [-Wdeprecated-declarations]
  s2/mutable_s2shape_index.cc:470:38: warning: 'exchange<int, int>' is deprecated [-Wdeprecated-declarations]
  s2/mutable_s2shape_index.cc:483:36: warning: 'exchange<int, int>' is deprecated [-Wdeprecated-declarations]
  s2/s2lax_loop_shape.cc:38:27: warning: 'exchange<int, int>' is deprecated [-Wdeprecated-declarations]
  s2/s2lax_loop_shape.cc:43:25: warning: 'exchange<int, int>' is deprecated [-Wdeprecated-declarations]
  s2/s2lax_loop_shape.cc:95:27: warning: 'exchange<int, int>' is deprecated [-Wdeprecated-declarations]
  s2/s2lax_loop_shape.cc:102:25: warning: 'exchange<int, int>' is deprecated [-Wdeprecated-declarations]
  : warning:   'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]289
   ../src/s2/util/math/vector.h:317:46: warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  s2/s2loop.cc:113:20: warning: 'exchange<int, int>' is deprecated [-Wdeprecated-declarations]
  s2/s2loop.cc:114:27: warning: 'exchange<int, int>' is deprecated [-Wdeprecated-declarations]
    146 |     return Base::DivCompons2/s2loop.cc:132:18: warning: 'exchange<int, int>' is deprecated [-Wdeprecated-declarations]
  s2/s2loop.cc:133:25: warning: 'exchange<int, int>' is deprecated [-Wdeprecated-declarations]
  53: warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  :70:31: warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]
  ../src/s2/s2shape_index.h:308:3: warning: 'decay_t' is deprecated [-Wdeprecated-declarations]
  ../src/s2/s2cell_range_iterator.h:122:36: warning: 'decay_t' is deprecated [-Wdeprecated-declarations]
  : warning: 'index_sequence' is deprecated: Use std::index_sequence instead. [-Wdeprecated-declarations]  
  s2/util/coding/coder.cc:35:18: warning: 'exchange<unsigned char *, std::nullptr_t>' is deprecated [-Wdeprecated-declarations]
  s2/util/coding/coder.cc:36:20: warning: 'exchange<unsigned char *, std::nullptr_t>' is deprecated [-Wdeprecated-declarations]
  s2/util/coding/coder.cc:37:32: warning: 'exchange<unsigned char *, std::nullptr_t>' is deprecated [-Wdeprecated-declarations]
  s2/util/coding/coder.cc:38:19: warning: 'exchange<unsigned char *, std::nullptr_t>' is deprecated [-Wdeprecated-declarations]
  s2/util/coding/coder.cc:43:16: warning: 'exchange<unsigned char *, std::nullptr_t>' is deprecated [-Wdeprecated-declarations]
  s2/util/coding/coder.cc:44:18: warning: 'exchange<unsigned char *, std::nullptr_t>' is deprecated [-Wdeprecated-declarations]
  s2/util/coding/coder.cc:45:30: warning: 'exchange<unsigned char *, std::nullptr_t>' is deprecated [-Wdeprecated-declarations]
  s2/util/coding/coder.cc:46:17: warning: 'exchange<unsigned char *, std::nullptr_t>' is deprecated [-Wdeprecated-declarations]
See ‘/data/localhost/ripley/R/packages/tests-clang/s2.Rcheck/00install.out’ for details.
* used C compiler: ‘clang version 22.1.8’
* used C++ compiler: ‘clang version 22.1.8’