Unknown but valid SPDX

[BenBals]

Describe the bug
Cabal does not recognize the BlueOak-1.0.0 license even though that is a valid SPDX expression per https://spdx.org/licenses/BlueOak-1.0.0.html

To Reproduce
Use the following cabal file:

cabal-version:       2.4

-- Initial package description 'turing.cabal' generated by 'cabal init'.
-- For further documentation, see http://haskell.org/cabal/users-guide/

-- The name of the package.
name:                turing

-- The package version.  See the Haskell package versioning policy (PVP)
-- for standards guiding when and how versions should be incremented.
-- https://pvp.haskell.org
-- PVP summary:      +-+------- breaking API changes
--                   | | +----- non-breaking API additions
--                   | | | +--- code changes with no API change
version:             0.1.0.0

-- A short (one-line) description of the package.
synopsis:            Encoding of turing machines

-- A longer description of the package.
-- description:

-- A URL where users can report bugs.
-- bug-reports:

-- The license under which the package is released.
license:             BlueOak-1.0.0

-- The file containing the license text.
license-file:        LICENSE.md

-- The package author(s).
author:              Ben Justus Bals

-- An email address to which users can send suggestions, bug reports, and
-- patches.
maintainer:          [email protected]

-- A copyright notice.
-- copyright:

category:            Language

-- Extra files to be distributed with the package, such as examples or a
-- README.
extra-source-files:  CHANGELOG.md


library
  -- Modules exported by the library.
  exposed-modules: Turing
                   Turing.Encode
                   Turing.Decode

  -- Modules included in this library but not exported.
  -- other-modules:

  -- LANGUAGE extensions used by modules in this package.
  -- other-extensions:

  -- Other library packages from which modules are imported.
  build-depends:       base ^>=4.12.0.0

  -- Directories containing source files.
  hs-source-dirs: lib

  -- Base language which the package is written in.
  default-language:    Haskell2010


executable turing
  -- .hs or .lhs file containing the Main module.
  main-is:             src/Main.hs

  -- Modules included in this executable, other than Main.
  -- other-modules:

  -- LANGUAGE extensions used by modules in this package.
  -- other-extensions:

  -- Other library packages from which modules are imported.
  build-depends:       base ^>=4.12.0.0

  -- Directories containing source files.
  hs-source-dirs: src

  -- Base language which the package is written in.
  default-language:    Haskell2010

Expected behavior
Cabal accepting the license.

System informataion

• cabal-install version 2.4.1.0
• Linux nixos-beb 4.19.58 Add support for the Apache license #1-NixOS SMP Wed Jul 10 07:53:48 UTC 2019 x86_64 GNU/Linux

[phadej]

BlueOak is relatively new license and wasn’t in SPDX license list used by cabal-version: 2.4. It will be available with cabal-version: 3.0. #6171

[BenBals]

Thank you very much for the information.