aes 0.9 runtime-detects the ARMv8-Crypto backend on aarch64 via `cpufeatures` and polyval 0.7
picks its armv8 PMULL intrinsics by target_arch, so neither cfg exists any more — passing them
is inert. That retires a real footgun rather than tidying a file: a RUSTFLAGS env var overrides
config rustflags ENTIRELY, so every aarch64 lane that set its own (cargo-ndk does so internally
for every Android arm64-v8a build) silently dropped both and ran SOFTWARE AES on the per-packet
decrypt path.
Measured before deleting, `crypto/open_in_place` (1408-byte MTU shard, AES-128-GCM, single core,
Mac15,14 M3 Ultra, four runs back to back under identical background load):
aes 0.8 + both cfgs 2.19 GiB/s
aes 0.8, cfgs stripped 225 MiB/s ~10x cliff — reproduces the recorded ~240 MiB/s
aes 0.9 + both cfgs 5.28 GiB/s
aes 0.9, cfgs stripped 5.28 GiB/s identical to 4 s.f.
The ChaCha20-Poly1305 series of the same bench was the control and moved 0.07% across the cfg
toggle at both versions, so the toggle demonstrably reached only the AES path. A final run with
the flags actually deleted (not merely RUSTFLAGS-overridden) reproduced 5.29 GiB/s.
.cargo/config.toml is kept as a tombstone carrying that table so the flags are not reintroduced.
The two CI comments that warned about losing these cfgs to a RUSTFLAGS override are updated —
mold in ci/cargo-config-mold.toml is now the only thing such an override can cost.
enricobuehler
c814340607