cargo rustc --release -- -C target-cpu=native --emit link=Reckless-AVX512-C0CF5BA1
   Compiling proc-macro2 v1.0.95
   Compiling unicode-ident v1.0.18
   Compiling glob v0.3.2
   Compiling prettyplease v0.2.32
   Compiling libc v0.2.175
   Compiling cfg-if v1.0.0
   Compiling regex-syntax v0.8.5
   Compiling memchr v2.7.4
   Compiling minimal-lexical v0.2.1
   Compiling shlex v1.3.0
   Compiling either v1.15.0
   Compiling bindgen v0.71.1
   Compiling bitflags v2.9.0
   Compiling log v0.4.27
   Compiling rustc-hash v2.1.1
   Compiling libloading v0.8.6
   Compiling cc v1.2.22
   Compiling itertools v0.13.0
   Compiling clang-sys v1.8.1
   Compiling nom v7.1.3
   Compiling quote v1.0.40
   Compiling syn v2.0.101
   Compiling regex-automata v0.4.9
   Compiling cexpr v0.6.0
   Compiling regex v1.11.1
   Compiling reckless v0.9.0-dev (/tmp/tmpm6449jtx/Reckless-AVX512/Reckless-AVX512-tmp)
error[E0554]: `#![feature]` may not be used on the stable release channel
 --> src/main.rs:4:1
  |
4 | #![feature(cfg_select)]
  | ^^^^^^^^^^^^^^^^^^^^^^^

For more information about this error, try `rustc --explain E0554`.
error: could not compile `reckless` (bin "reckless") due to 1 previous error
make: *** [Makefile:24: rule] Error 101