Fix slice reference encoding for array parameters#115
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sqlx 0.9's blanket `impl Encode for &T` requires `T: Sized`, so it does not cover `&[T]` (the pointee `[T]` is unsized). As a result, binding a slice reference such as `&[i32]` or `&[&str]` as an array parameter no longer compiled for the element types declared via `generic_slice_decl!`, while the hand-written `uuid` impls still worked — an inconsistent regression in 0.6.0. Add the missing `&[$elem]` forward to `forward_slice_encode_deref!` so the macro-declared element types regain parity with `uuid`, and add a compile-time regression test covering the affected element types. Fixes #114
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Summary
This PR fixes an issue where slice references (
&[T]) could not be bound as array parameters in SQL queries. The fix involves explicitly forwarding theEncodeimplementation for slice references and adding regression tests to ensure the fix works across all supported element types.Key Changes
forward_slice_encode_deref!macro: Added explicit forwarding for&'_ [$elem]slice references. This is necessary because sqlx 0.9's blanketimpl Encode for &TrequiresT: Sized, which doesn't cover unsized slice types&[T].Cow<'_, [$elem]>is already covered by blanket impls.&[T]implementsEncodefor all supported element types (i8, i16, i32, i64, f32, f64, bool, &str, String, and uuid::Uuid when the uuid feature is enabled).Implementation Details
The fix leverages the existing
forward_encode_deref!macro to create the necessaryEncodeimplementations for slice references. The test uses a compile-time assertion pattern (assert_encode::<T>()) to ensure that the trait bounds are satisfied, which will catch any regressions if the forwarding implementations are accidentally removed or broken.https://claude.ai/code/session_0175YJdZtGPi5MhpF6HYErzC