whereis with no version tries the recommended, rather than active version

[hseg]

Running ghcup whereis ghc behaves like ghcup whereis recommended.
In particular, if one is on a system where the recommended ghc version is not installed (even if the "active ghc" is set appropriately using ghcup set ghc to an existing version), this spuriously gives GHCup-00130 errors.

[hasufell]

This is by design. You're proposing a different design. But are you aware that you can have no GHC version set at all? What does it do then? Also fail?

I agree it might be slightly more intuitive for it to return the set version, but it's a breaking change.

How do we migrate? It can break scripts, CIs etc.

[hseg]

On Mon, Jan 22, 2024 at 07:56:50PM -0800, Julian Ospald wrote: This is by design. You're proposing a different design. But are you aware that you can have **no GHC version set at all**? What does it do then? Also fail? I agree it might be slightly more intuitive for it to return the **set** version, but it's a breaking change. How do we migrate? It can break scripts, CIs etc.

Ah, was unaware this was the design. Yes, I'd expect a *distinct* failure mode if there is no GHC version set. After all, we're querying the current system state -- if people are using the empty version to test whether the recommended version is installed at all, I'd expect them to use `ghcup list -t ghc -c installed | grep recommended` or somesuch. Could we at least teach `whereis` a new version `default` evaluating to the set version? That way, at least the semantics I'd intuited are expressible. And that'd also make available the usual three-release deprecation cycle: warn that `whereis` without a version is deprecated, then either pull the feature or replace the semantics with `whereis $tool default`. Or I guess we could gate `default-whereis-version` behind a config option.

[hasufell]

Could we at least teach whereis a new version default evaluating to the set version?

Finding the set version is pretty easy via:

ghcup whereis bindir
$(ghcup whereis bindir)/ghc --version

[hseg]

On Thu, Jan 25, 2024 at 11:28:17PM -0800, Julian Ospald wrote: > Could we at least teach `whereis` a new version `default` evaluating to the set version? Finding the *set* version is pretty easy via: ```sh ghcup whereis bindir $(ghcup whereis bindir)/ghc --version ```

Fair enough. Would be worth documenting somewhere, though -- this doesn't appear neither in the user guide or the `ghcup whereis` usage -- especially since, as you agreed, the current behaviour is unintuitive.