Use nonempty where possible

[Byron]

Tasks

• review breaking change declaration
• review line by line

[Copilot]

Pull request overview

This PR replaces various Vec<T>/slice usages that are expected to be non-empty with nonempty::NonEmpty<T> to encode invariants in types across gix-* crates, and updates dependent code/tests accordingly.

Changes:

• Introduce nonempty::NonEmpty in shallow-boundary, merge-base, merge outcomes, commit-graph, and select internal iterators.
• Adjust algorithms and call sites to use first()/tail() and NonEmpty::from_vec() patterns.
• Add nonempty dependencies (and serde feature wiring where needed) and update tests to compare against Vec as needed.

Reviewed changes

Copilot reviewed 31 out of 32 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
gix/tests/gix/repository/shallow.rs	Update shallow-commit assertions to work with NonEmpty.
gix/tests/gix/remote/fetch.rs	Update shallow-commit assertions to work with NonEmpty.
gix/tests/gix/clone.rs	Update shallow-commit assertions to work with NonEmpty.
gix/src/shallow.rs	Change shallow commit snapshot storage from Vec to NonEmpty.
gix/src/revision/walk.rs	Adjust shallow-boundary membership check for NonEmpty storage layout.
gix/src/repository/revision.rs	Update merge-base selection to use NonEmpty::first().
gix/src/merge.rs	Change merge outcome merge_bases to Option<NonEmpty<_>>.
gix/Cargo.toml	Add nonempty dependency.
gix-shallow/src/lib.rs	Change shallow read/write APIs to return/take Option<NonEmpty<_>>.
gix-shallow/Cargo.toml	Add nonempty dependency and serde feature wiring.
gix-revision/tests/revision/merge_base/mod.rs	Adapt tests to compare Option<NonEmpty<_>> via Vec::from.
gix-revision/src/merge_base/mod.rs	Update octopus merge-base logic to use NonEmpty::first().
gix-revision/src/merge_base/function.rs	Change merge-base return type to Option<NonEmpty<_>>.
gix-revision/Cargo.toml	Add nonempty dependency.
gix-protocol/src/fetch/function.rs	Plumb shallow commits as Option<NonEmpty<_>> through fetch argument building.
gix-protocol/Cargo.toml	Add nonempty dependency.
gix-odb/src/store_impls/dynamic/write.rs	Minor refactor using first() + improved expect message.
gix-odb/src/store_impls/dynamic/iter.rs	Use NonEmpty for loose ODB list in iterator state.
gix-odb/Cargo.toml	Add nonempty dependency.
gix-merge/src/tree/utils.rs	Use NonEmpty for TreeNodes internal storage.
gix-merge/src/commit/virtual_merge_base.rs	Make virtual_merge_bases non-empty by construction.
gix-merge/src/commit/mod.rs	Change commit-merge outcome merge_bases to Option<NonEmpty<_>>.
gix-merge/src/commit/function.rs	Adapt merge-base handling to NonEmpty APIs and conversions.
gix-merge/Cargo.toml	Add nonempty dependency.
gix-commitgraph/src/verify.rs	Adjust base-graph checksum iteration for NonEmpty storage.
gix-commitgraph/src/lib.rs	Make Graph.files non-empty.
gix-commitgraph/src/init.rs	Validate non-empty file list at Graph::new() construction.
gix-commitgraph/src/access.rs	Simplify object_hash() using non-empty invariant.
gix-commitgraph/Cargo.toml	Add nonempty dependency.
gitoxide-core/src/hours/mod.rs	Pass non-empty commit slices via split_first() to avoid empty handling.
gitoxide-core/src/hours/core.rs	Change estimate_hours() signature to accept an explicit first commit + rest.
Cargo.lock	Record nonempty crate resolution and propagated deps.

[Copilot]

Pull request overview

Copilot reviewed 25 out of 26 changed files in this pull request and generated 1 comment.