[Bug] dbt.date() fails on DuckDB — no duckdb__date, so default__date emits unsupported to_date() #15801

Summary

dbt.date() has no DuckDB override, so it dispatches to default__date, which emits to_date('YYYY-MM-DD', 'YYYY-MM-DD'). DuckDB has no to_date function, so any project calling the documented pattern of dbt.date_spine() with dbt.date() boundaries fails on a DuckDB target.

date() is a documented cross-database macro, and pairing it with date_spine() is an intended usage pattern, so this is a plain gap rather than misuse.

Reproduction

Found and verified while testing dbt-labs/jaffle-shop#103 against dbt-core 1.12 + DuckDB locally.

{{ dbt.date_spine(
    datepart="day",
    start_date=dbt.date(2020, 1, 1),
    end_date=dbt.date(2021, 1, 1)
) }}

Fails on DuckDB because the rendered SQL contains to_date(...).

Fix

Add a duckdb__date override using DuckDB's native make_date(year, month, day) constructor, mirroring the existing bigquery__date pattern (native constructor rather than string parsing).

Open question worth resolving alongside

These adapter macros are vendored from duckdb/dbt-duckdb — the sibling dateadd.sql and datediff.sql already carry DuckDB overrides, which is why date() stands out as an omission. Worth confirming whether the same gap exists in dbt-duckdb itself for the Core v1 path, and if so upstreaming it there too rather than only patching the vendored copy.

PR

dbt-labs/fs#12243 (open).