pureconfig / pureconfig / 28124501993

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Commit Message

Use case class defaults in Scala 3 `derives` derivation (#1943)

Fixes 1673: `ConfigReader`s derived in Scala 3 via `derives` clauses
fail with `KeyNotFound` when the key for a parameter with a default
value is missing from the config.

This moves the `getDefaults` macro from `pureconfig-generic-scala3`
to `pureconfig-core` and uses it in the case-class branch of the core
derivation, with `pureconfig-generic-scala3` reusing it from its new
location — the approach suggested in the review of 1675, and one of
the code-reuse follow-ups anticipated in 1636.

The semantics follow the hints-aware derivation under the default
`ProductHint`: a default is used exactly when its key is missing,
taking precedence over `ReadsMissingKeys` readers, and defaults are
evaluated lazily (preserving the 1218 fix). With this change,
`derives` parses the same configs to the same values as
`pureconfig-generic-scala3` under default hints. Hint support in
`derives` remains intentionally out of scope (1742).

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: Rui Gonçalves <ruippeixotog@gmail.com>

Coverage Stats

15 of 15 new or added lines in 2 files covered. (100.0%)

8 existing lines in 6 files now uncovered.

2764 of 2921 relevant lines covered (94.63%)

2.37 hits per line