Add a triage document for the `dart migrate` tool.
Change-Id: I4ba33889c6171d012fc6a4239f4409c5fe9de005
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/172661
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Devon Carew <devoncarew@google.com>
diff --git a/pkg/nnbd_migration/TRIAGE.md b/pkg/nnbd_migration/TRIAGE.md
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+# Triage Priorities for Dart Migration tool
+
+This document describes the relative priorities for bugs filed under the
+`area-migration` tag in GitHub as in
+[this search](https://github.com/dart-lang/sdk/issues?q=is%3Aopen+is%3Aissue+label%3Aarea-migration).
+While there are always exceptions to any rule, in general try to align our
+priorities with these definitions.
+
+To triage bugs, search for `area-migration`
+[bugs that are not currently triaged](https://github.com/dart-lang/sdk/issues?q=is%3Aopen+is%3Aissue+label%3Aarea-migration+-label%3AP0+-label%3AP1+-label%3AP2+-label%3AP3+-label%3AP4)
+and for each bug, mark priority based on how closely it matches with the below
+constraints.
+
+## Migration tool triage priorities
+
+Descriptions here use [terms and definitions](#terms-and-definitions) from the
+end of this document. If your bug doesn't precisely match one of these,
+consider how impactful it is compared to examples given here and pick a priority
+reflecting that.
+
+### P0
+
+* Crashes that can't be worked around by `--ignore-exceptions`, typical impact or widespread.
+* Crashes that can be worked around by `--ignore-exceptions`, widespread.
+
+### P1
+
+* Crashes that can be worked around by `--ignore-exceptions`, typical impact.
+* An enhancement required for critical milestones for key users, or that has
+ significant evidence gathered indicating a positive impact if implemented.
+* A problem that is significantly impairing a key user's ability to migrate
+ their code.
+
+### P2
+
+* Crashes, edge case.
+* An enhancement with typical impact that doesn't fit the criteria above but
+ would still be significantly beneficial to users (i.e. more than just a "would
+ be nice" feature).
+* A problem with typical impact that doesn't fit the criteria above, but impairs
+ users' ability to migrate their code.
+
+### P3
+
+* Crashes, theoretical.
+* An enhancement that doesn't fit the criteria above.
+* A problem that doesn't fit the criteria above, but impairs users' ability to
+ migrate their code.
+
+## Terms and definitions
+
+### Terms describing impact
+
+* "widespread" - Impact endemic throughout the ecosystem, or at least far
+ enough that this is impacting multiple key users.
+* "typical impact" - Known to impact a key user, or likely to impact a
+ significant percentage of all users. Issues are assumed to have typical
+ impact unless we have evidence otherwise.
+* "edge cases" - Impacting only small parts of the ecosystem. For example, one
+ package, or one key user with a workaround. Note this is an edge case from
+ the perspective of the ecosystem vs. language definition. Note that since the
+ migration tool is still in an early adoption phase, if a bug has only been
+ reported by one user, that's not sufficient evidence that it's an edge case.
+ To be considered an edge case, we need to have a concrete reason to suspect
+ that the bug is caused by an unusual pattern in the user's source code, or
+ unusual user behavior.
+* "theoretical" - Something that we think is unlikely to happen in the wild
+ and there's no evidence for it happening in the wild.
+
+### Other terms
+
+* "key users" - Flutter, Pub, Fuchsia, Dart, Google3, 1P
