These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.77 s (backtrack: 0/20).

[ebuild  N     ] dev-libs/nspr-4.40::gentoo  USE="-debug" 986 KiB
[ebuild  NS    ] dev-lang/rust-bin-1.98.1:1.98.1::gentoo [1.94.0:1.94.0::gentoo] USE="clippy rustfmt (-big-endian) -doc* (-prefix) -rust-analyzer -rust-src -verify-sig" CPU_FLAGS_X86="sse2" LLVM_SLOT="(22%*) (-21%*)" 197813 KiB
[ebuild  N     ] dev-util/cbindgen-0.29.4::gentoo  USE="-debug -test" 6453 KiB
[ebuild  N     ] dev-lang/spidermonkey-153.3.0:153/153.1.0::gentoo  USE="jit -clang -debug -test" LLVM_SLOT="22" 786147 KiB

Total: 4 packages (3 new, 1 in new slot), Size of downloads: 991397 KiB