A colleague of mine is trying to check FLINT built under macOS. He does not hit #2048, perhaps because his architecture is x86_64 rather than aarch64 ... ? But he encounters a linker error at a later stage:

$ make check
<...>
   CC  mag/test/main.c
duplicate symbol '_d_randtest2' in:
     /private/var/folders/rr/q47s6xq93n1_lhj48t9rmqkr0000gn/T/main-4a8524.o
     ./libflint.a[85](double_interval_merged.o)
ld: 1 duplicate symbols
clang: error: linker command failed with exit code 1 (use -v to see 
invocation)
make: *** [build/mag/test/main] Error 1

Indeed, I see d_randtest2 defined twice (in the double_interval module and again in the tests), but perhaps other linkers have ignored it. He is, like me, using the native Apple LLVM, not Homebrew LLVM ...