A `cargo report list` command to list available sessions to generate report from

[weihanglo]

Problem

With -Zbuild-analysis and #16377, we now have cargo report timings command to replay HTML report from the latest log files. However, there is no way to replay older sessions. We may want a cargo report timings --id <id> flag to reply specific run of Cargo.

Before adding that flag, we need a way to list and view past run IDs.

Proposed Solution

A new command cargo report list. The list of IDs is expected to work across different kind of reports.

Notes

No response

[weihanglo]

There is a minor annoyance that cargo report future-incompat is not based on the -Zbuild-analysis structured logging.

[ehuss]

My intention for the report subcommand was to have it cover all sorts of different kinds of reports, not all of which would be directly related to a recent build. Like there could be various commands that do analysis on the project and produce some kind of report about it. In those cases, there wouldn't be anything to "list" since it isn't necessarily fetching a pre-made report.

Would it be ok to just add a list option to the individual subcommands. For example, cargo report timings --list or cargo report future-incompat --list?

[epage]

The original plan in #16377 was to add a --list in a follow up. I raised the concern about --list and suggested list in #16377 (comment).

[epage]

I have a general concern about flags that change a command's mode and our ability to easily express any additional functionality for that mode. Here we have a potential for a lot of commands that will all use the same concept of an ID while operating under a parent subcommand. I feel like this gives us a good opportunity to go ahead and break this interface out into a separate command with all of the interface flexibility that provides.

[epage]

If we decide to have this as a subcommand, we could qualify the name, like list-runs or something.

[weihanglo]

For listing recent builds, it might be better as a command because we might want to have a time range query over that, and putting it under --list doesn't feel right with other query flags, and also need a more complex flag handling logic.

Or maybe we can make it sounds like a kind of report.

cargo report recent-builds --since 2025-11-01 --until 2025-12-31 --format json

So it feels more nature to be a subcommand under cargo report.