softwaremill / softwaremill/tapir

Show precise errors for failed derivation for Pickler

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Pickler
Dominant language
Scala
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Description

Current behavior: When Tapir fails to derive a Pickler for a type because of missing Pickler for one of its fields, we show a compilation error pointing which field type failed derivation.
image

Expected improvement: It would be great to show the full path (like "breadcrumbs") of implicit resolution that led to the point of failed summoning. The user would have a better understanding of where exactly the issue happened.
For deeper errors, we'd like to show something like

Failed to summon Pickler[example.Country] when deriving from example.Book > example.Author

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start from Pickler derivation and the existing compilation error that identifies the failed field type. Trace how nested derivation failures are reported, then make the diagnostic include the full derivation path, such as example.Book > example.Author, and verify the deeper error wording.

Written by the indexing model from the issue text.

Assessment

Tech stack
scala
Domain
developer-experience
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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