error[E0658]: use of unstable library feature 'alloc': this library is unlikely to be stabilized in its current form or name (see issue #27783)

   --> /home/travis/.cargo/registry/src/github.com-1ecc6299db9ec823/enum_variant_type-0.2.1/src/lib.rs:144:1

    |

144 | extern crate alloc;

    | ^^^^^^^^^^^^^^^^^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0658`.

error: Could not compile `enum_variant_type`.

verbose: creating temp file: C:\Users\appveyor\.rustup\tmp\5vzkbz8b4rvu6tfk_file
verbose: creating temp file: C:\Users\appveyor\.rustup\tmp\5wypi_xgi7diffwp_file
verbose: deleted temp directory: C:\Users\appveyor\.rustup\tmp\b658ydoei39unwji_dir
info: installing component 'rust-std'
verbose: creating temp directory: C:\Users\appveyor\.rustup\tmp\h32i514dflmtq_j2_dir
memory allocation of 16777216 bytes failed
Command exited with code -1073740791