✨ zlink-macros: Support rename_all_arguments on the proxy macro

[Copilot]

systemd's Varlink APIs use camelCase for method arguments per their Varlink API style guide, with PascalCase where a name mirrors a documented option name (the Varlink spec itself mandates no case convention; its own examples are snake_case). Rust arguments are snake_case, so today each argument of a proxy for such a service must be individually annotated with #[zlink(rename = "...")] — see the machined mock in zlink/tests/mock_machined_service.rs, which hand-renames every argument. This adds rename_all_arguments to the #[proxy] macro so a single attribute converts all argument names automatically. The attribute is deliberately not called rename_all: the explicit name makes it obvious it renames the method arguments, not the methods.

#[proxy(interface = "org.example.Config", rename_all_arguments = "camelCase")]
trait ConfigProxy {
    async fn set_config(
        &mut self,
        dry_run: bool,        // serialized as "dryRun"
        config_value: String, // serialized as "configValue"
    ) -> zlink::Result<Result<(), Error>>;
}

Per-argument #[zlink(rename = "...")] takes precedence over rename_all_arguments, which irregular names (e.g. machined's OSRelease, UIDShift) still need. The convention is applied to the unraw'd ident (r#type under PascalCase maps to Type, not R#type), and every produced name is validated against the Varlink field grammar — matching what the derives and the service macro already guarantee since #296 — so e.g. kebab-case on a multi-word argument is a compile error, not an invalid wire name.

Fixes #170.

Changes

• naming.rs: Widen RenameAll::parse to pub(crate), make its unknown-value error attribute-neutral
• proxy.rs: Parse rename_all_arguments from proxy attributes, thread it to all three code generators
• proxy/utils.rs: New resolve_serialized_name helper holding the precedence rule, the unrawing, and the grammar validation in one place
• method_impl.rs / chain_extension.rs / chain_method.rs: Resolve argument wire names through the shared helper
• lib.rs: Document rename_all_arguments in the supported-attributes list, including the systemd camelCase guidance and the grammar constraint (with a compile_fail doctest)
• tests/proxy/rename.rs: Tests for PascalCase, camelCase, explicit-override precedence, chain methods, and raw identifiers (plain and chained)

[Copilot]

Pull request overview

This PR extends the #[proxy] macro in zlink-macros to support a rename_all = "...“ attribute, allowing proxy method parameter names to be case-converted automatically (with per-parameter #[zlink(rename = "...")] still taking precedence). This fits the macros crate’s role of generating client-side Varlink proxy code with correct wire-format naming.

Changes:

• Parse rename_all from #[proxy(...)] attributes and thread it through proxy method / chain method code generation.
• Apply RenameAll::apply_to_field to parameters that do not have an explicit #[zlink(rename = "...")].
• Add/extend tests and documentation to cover rename_all usage and precedence.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
zlink-macros/src/naming.rs	Exposes RenameAll::parse to allow proxy macro parsing.
zlink-macros/src/proxy.rs	Parses rename_all from proxy attributes and passes it into generators.
zlink-macros/src/proxy/method_impl.rs	Applies rename_all when generating serde parameter structs (method impl path).
zlink-macros/src/proxy/chain_method.rs	Applies rename_all for chain methods’ parameter serialization.
zlink-macros/src/proxy/chain_extension.rs	Applies rename_all for chain extension methods’ parameter serialization.
zlink-macros/src/lib.rs	Documents rename_all as a supported #[proxy] attribute and lists accepted values.
zlink-macros/tests/proxy/rename.rs	Adds tests for rename_all (PascalCase/camelCase), explicit override precedence, and chain methods.

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[codspeed-hq]

Merging this PR will not alter performance

✅ 4 untouched benchmarks

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_{Comparing copilot/add-attribute-rename-method-arguments (798aa8f) with main (27552b9)}

[zeenix]

Reviewed on top of the existing comments (not repeating them). The raw-identifier issue already flagged in three files is real; two additional findings inline: (1) rename_all-produced names are never validated against the Varlink field grammar, so documented values like kebab-case silently emit wire names Varlink cannot express — the opposite of what #298 established for the derives; (2) the resolution logic is triplicated across the three codegen files, which is why the raw-ident bug appears three times — it should be a single shared helper. Fixes for all comments follow on claude/zlink-pr-299-review-r18v2c.

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