$ which gprbuild
/home/laguest/opt/free-ada-9.3.0/bin/gprbuild
$ alr clean
Welcome to the toolchain selection assistant
In this assistant you can set up the default toolchain to be used with any crate
that does not specify its own top-level dependency on a version of gnat or
gprbuild.
If you choose "None", Alire will use whatever version is found in the
environment.
ⓘ gnat is currently not configured. (alr will use the version found in the environment.)
Please select the gnat version for use with this configuration
1. gnat_native=11.2.1
2. None
3. gnat_external=9.3.0 [Detected at /home/laguest/opt/free-ada-9.3.0/bin/gnat]
4. gnat_arm_elf=11.2.1
5. gnat_riscv64_elf=11.2.1
6. gnat_arm_elf=10.3.1
7. gnat_native=10.3.1
8. gnat_riscv64_elf=10.3.1
Enter your choice index (first is default):
> 3
ⓘ Selected tool version gnat_external=9.3.0
ⓘ Choices for the following tool are narrowed down to releases compatible with just selected gnat_external=9.3.0
ⓘ gprbuild is currently not configured. (alr will use the version found in the environment.)
Please select the gprbuild version for use with this configuration
1. None
Enter your choice index (first is default):
> 
alire-project / alire
Command-line tool from the Alire project and supporting library
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