feat: bootstrap jiff-sqlx development

[tisonkun]

This refers to #50.

Firstly, I considered to add a separated sqlx-jiff method, but soon I found that due to Rust's orphan rules, implementing sqlx's trait for Timestamp and other types requires the code to be located at the same crate (jiff). Otherwise we need an extra wrapper struct like:

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct Timestamp(pub jiff::Timestamp);

I prefer to implement code in jiff and gate it with feature flags.

@BurntSushi This demonstrates the integration implementation direction. I'll complete other parts when we agree on this direction.

[BurntSushi]

#50 (comment) discusses this. And the orphan rule is taken into account there. The way to do this integration, short of getting it merged upstream in sqlx itself, is with a wrapper type in a jiff-sqlx crate. The comment linked explains how to do this.

Jiff is a "low level" crate. Having it depend on "high level" crates like sqlx would lead to all sorts of problems, especially if and when the time ever comes for sqlx to add Jiff integration on their end. It's really a non-starter.

[tisonkun]

@BurntSushi Yeah .. Adopt the other way now.

[BurntSushi]

Also, the crate should be called jiff-sqlx, since it lives with jiff.

[tisonkun]

Other type mapping to be wrapped once we agree on the pattern:

• jiff::civil::Date <-> DATE
• jiff::civil:Time <-> TIME
• jiff:civil::DateTime <-> TIMESTAMP
• jiff::Timestamp <-> TIMESTAMPTZ
• jiff::SignedDuration <-> INTERVAL

Ref -

• feat: support jiff integration for postgresql launchbadge/sqlx#3511
• Add Jiff support sfackler/rust-postgres#1164

[tisonkun]

All bridges submitted. Note that integrations for PgRange and PgTimeTz cannot be added due to the orphan rule.

I'd suspend the task here to start jiff-sqlx with Postgres support first since it's my real use case and I'd avoid adding too many things at the very beginning.

[tisonkun]

The failing wasm CI job doesn't seem to be relevant to this patch ..

[maxcountryman]

• jiff::SignedDuration <-> INTERVAL

I'm curious why this wouldn't be jiff::Span? That's how I'm doing these conversions manually.

[tisonkun]

@maxcountryman

It's possible to support multiple type mappings, so it's possible to support both Span and Duration.

However, PG's interval supports only months, days and microseconds parts. Span supports other units. I'm not sure if we can always assume 1 year=12 months, and 1 week=7days.

Anyway, we may support two types together.

[maxcountryman]

Span supports other units. I'm not sure if we can always assume 1 year=12 months, and 1 week=7days.

As I understand, Span doesn't assume 12 months == 1 year (ergo keeping each unit as a discrete property). I think that might be a reason to use Span here, right? (In particular, I believe Span is needed for full ISO 8601 support.)