[kinyoklion]

Summary

When a migration flag evaluates to a string that is not a migration stage, migrationVariation replaces the detail with a WRONG_TYPE error for the default stage. The replacement dropped the evaluation's overrideAffected marking, so an overridden migration flag with an unrecognized stage gave the MigrationOpTracker an unmarked reason. OVERRIDE 1.5.4 marks an evaluation that fails when a definition it read came from the override store. The same review finding was made on the .NET port (dotnet-core #364).

The new reason now keeps the marking, the same way variationAndFlag keeps it when a requested-type mismatch replaces the reason. A migration flag that serves a value that is not a string already kept it: that path goes through variationAndFlag's type check, and the default stage then parses. Evaluation events are unchanged, because they are recorded before the stage is parsed and carry the marking from the evaluation result.

Tests

ldclient_overrides_test.go: an overridden migration flag that serves "not-a-stage" returns the default stage and an error, and the operation event that its tracker builds carries a WRONG_TYPE reason marked overrideAffected. It fails before the change and when the fix is reverted. go test -race ./... passes; make lint reports no issues.

_{Opened from termag}

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Note

Overview
When MigrationVariation gets a string that is not a valid migration stage, it replaces the evaluation detail with a WRONG_TYPE error and the default stage. That replacement used to drop overrideAffected, so migration operation events from MigrationOpTracker could look like a normal (non-override) failure even when the value came from the override layer.

The fix copies the prior reason’s overrideAffected flag onto the new error reason—the same pattern variationAndFlag already uses for type mismatches. Standard flag evaluation events are unchanged; they are emitted before stage parsing.

A test covers an overridden migration flag serving "not-a-stage" and asserts the built operation event’s reason is WRONG_TYPE with overrideAffected: true.

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[kinyoklion]

bugbot review