[bug] "conan install" detects the wrong compiler version with gcc 10 and fails

I am trying to upgrade one of my projects to use gcc 10 so I can use some C++20 features, but I ran into some issues with Conan not wanting to cooperate with the newer gcc version.

See this question for my initial findings: https://github.com/conan-io/conan/issues/6538

It turns out that even after I add “10” as a valid compiler version in “~/.conan/settings.yml” the “conan install” command still looks for the wrong version and fails saying that “1” is not a valid version.

As a temporary workaround I am able to add “1” to the list of versions in “~/.conan/settings.yml” but there’s definitely something wrong going on here. Once I add “1” it works.

Environment Details (include every applicable attribute)

• Operating System+version: Ubuntu 19.1.0
• Compiler+version: gcc 10.0.1
• Conan version: 1.22.1
• Python version: 2.7.17

Steps to reproduce (Include if Applicable)

1. Try to use Conan with a project that uses gcc 10 as the compiler. (currently to use gcc 10 it must be built from source here https://github.com/gcc-mirror/gcc)
2. Add version “10” as a valid compiler in “~/.conan/settings.yml”
3. Attempt to do “conan install” for the project (it will fail saying version “1” is not valid)

ERROR: Invalid setting '1' is not a valid 'settings.compiler.version' value.
Possible values are ['10', '4.1', '4.4', '4.5', '4.6', '4.7', '4.8', '4.9', '5', '5.1', '5.2', '5.3', '5.4', '5.5', '6', '6.1', '6.2', '6.3', '6.4', '7', '7.1', '7.2', '7.3', '7.4', '8', '8.1', '8.2', '8.3', '9', '9.1', '9.2']

1. Add version “1” to the list (even though this seems totally wrong)
2. Try again – “conan install” will work.