The .cargo/config.toml used [build] rustflags which applies globally
to every target. On aarch64-apple-darwin this injects
target-cpu=x86-64-v3 and +ssse3 as "ignored features", but the ring
crate's static CPU feature assertions detect the perturbed feature
set and fail to compile with:
error[E0080]: evaluation panicked:
assertion failed: CAPS_STATIC == MIN_STATIC_FEATURES
at ring-0.17.14/src/cpu/arm/darwin.rs:51
Move the flags under [target.'cfg(target_arch = "x86_64")'] so only
x86_64 builds see them. ARM/Apple Silicon targets get their own AES
hardware path automatically via the aes crate's armv8 dispatch — no
explicit flags needed.
cc