Avoid redundant enumeration of all package versions during solve failure

[zanieb]

error: Because the current Python version (3.9.6) does not satisfy Python>=3.11,<4.0 and all versions of rooster-blue depend on Python>=3.11,<4.0, we can conclude that all versions of rooster-blue cannot be used.
And because only the following versions of rooster-blue are available:
    rooster-blue==0.0.1
    rooster-blue==0.0.2
    rooster-blue==0.0.3
    rooster-blue==0.0.4
and you require rooster-blue, we can conclude that the requirements are unsatisfiable.

There's no reason for this message to be so verbose. We already said all versions of rooster-blue cannot be used. The conclusion could be:

And because you require rooster-blue, we can conclude that the requirements are unsatisfiable.

[charliermarsh]

How would you go about solving this?

[zanieb]

I'm not sure. I think the latter half comes from

uv/crates/uv-resolver/src/pubgrub/report.rs

Lines 280 to 293 in 57ea55d

	fn and_explain_external(
	&self,
	external: &External<PubGrubPackage, Range<Version>, UnavailableReason>,
	current_terms: &Map<PubGrubPackage, Term<Range<Version>>>,
	) -> String {
	let external = self.format_external(external);
	let terms = self.format_terms(current_terms);
	format!(
	"And because {}we can conclude that {}",
	Padded::from_string("", &external, ", "),
	Padded::from_string("", &terms, "."),
	)
	}

which doesn't have a obvious way to inspect that we previously concluded that "all versions cannot be used".

Maybe we don't need to know that we said that previously and instead we should just have better handling at

uv/crates/uv-resolver/src/pubgrub/report.rs

Lines 92 to 99 in 57ea55d

	// Complex case, there are multiple ranges
	} else {
	format!(
	"only the following versions of {} {}",
	package,
	PackageRange::available(package, &complement)
	)
	}

and collapse that to "all versions" when we see we're enumerating all of the available versions