Add GRDBDynamic trait.

[VentanYu]

Context

SQLiteData currently links the static GRDB library from GRDB.swift, which offers two products: GRDB (static) and GRDB-dynamic. GRDB's documentation recommends GRDB-dynamic when a package is linked into multiple targets within a single app, so all targets share one dynamic framework instead of each embedding a copy of the GRDB code.

When SQLiteData is consumed by several frameworks in the same app (e.g. a multi-framework project), the statically embedded GRDB code causes conflicts.

Changes

• Adds a GRDBDynamic trait to the package.
• When the trait is enabled, SQLiteData links the GRDB-dynamic product of GRDB.swift instead of the static GRDB product.
• The default behavior is unchanged: without the trait, the static GRDB library is linked as before.

Usage

Enable the trait when declaring the dependency (requires SwiftPM 6.1+):

.package(url: "https://github.com/pointfreeco/sqlite-data", from: "…", traits: ["GRDBDynamic"])

Verification

• swift build (default) and swift build --traits GRDBDynamic both pass; the trait-enabled build produces libGRDB-dynamic.dylib.
• Verified in a production app with multiple frameworks (Swift ≥ 6.1).
• Package@swift-6.0.swift is untouched (traits require SwiftPM 6.1+, so the 6.0 fallback keeps the static GRDB).

[stephencelis]

Thanks for looking into this! Just one thing to think on…

[stephencelis]

GRDB's README states:

GRDB offers two libraries, GRDB and GRDB-dynamic. Pick only one.

So I do wonder if this is legit to do or if it could lead to linking problems down the line. And I guess there's no way to negate a package condition 😕

We'll think on it, but I wonder if traits aren't the right tool here after all.

[VentanYu]

In my current build tests, when the trait is enabled, SPM automatically picks GRDB-dynamic over GRDB. I’m not entirely sure how it makes that decision, but it does work for now.

That said, depending on both products at the same time does feel a bit odd, and can’t be sure this behavior won’t change later. A more reliable approach might be to expose two separate products and avoid using traits altogether.