In R CMD check, only notify about snapshots once

[hadley]

Fixes #2207

[claude]

Claude finished @hadley's task —— View job

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Review

Issues found:

1. Unused field in R/reporter-check.R:16: has_snapshot_failure is added but never used anywhere

2. Minor inefficiency in R/snapshot-file.R:145-148: When in_rcmd_check() is true, hint is set to empty string but snapshot_review_hint() is still called unnecessarily

Otherwise the implementation looks correct - snapshot hints are now only shown in the check reporter when there are actual snapshot failures, which addresses the goal of notifying once.

[hadley]

@gaborcsardi can you take a look at this? Mostly so you know about it as you work on the next version of the CheckReporter.

[gaborcsardi]

Nice improvement! Left a comment.

[gaborcsardi]

I think the wording here can be misleading. Not just this line, the whole copy part. A failing snapshot does not necessarily mean that you need to update the snapshots, maybe it is a genuine test failure. (If I understand correctly when this is invoked.) Or it is a problem of platform dependent snapshots, in which case you can't simply update the snapshot files.

[hadley]

Hmmm, yeah the advice is supposed to more about how to diagnose the failure locally. I'll tweak.