Clang 17 has, at least with WiredTiger's build flags, started enforcing that names beginning with a double underscore are reserved.
With the following compile flags: cmake -DCMAKE_TOOLCHAIN_FILE=../cmake/toolchains/clang.cmake -DENABLE_PYTHON=1 -DHAVE_DIAGNOSTIC=1 -DENABLE_STRICT=1 -DCMAKE_EXPORT_COMPILE_COMMANDS=1 -G Ninja ../.
When using Clang 17, many warnings like this are generated:
wiredtiger/build/include/wiredtiger.h:70:8: error: identifier '__wt_compressor' is reserved because it starts with '__' [-Werror,-Wreserved-identifier] 70 | struct __wt_compressor; typedef struct __wt_compressor WT_COMPRESSOR;
A full log is attached.