refactor(azure_policy): reduce AliasRegistry allocations via Rc sharing

[anakrish]

Summary

Eliminates cloning two 73K-entry BTreeMaps on every Azure Policy compilation by sharing the AliasRegistry through a reference-counted pointer.

Changes

Compiler — replaces two owned map fields (alias_map, alias_modifiable) with Option<Rc<AliasRegistry>>. The three compile_*_with_aliases entry points now take Rc<AliasRegistry> instead of two separate maps:

// Before: two cloned maps (73K entries each)
compile_policy_definition_with_aliases(&defn, registry.alias_map(), registry.alias_modifiable_map())

// After: cheap Rc clone
compile_policy_definition_with_aliases(&defn, Rc::clone(&registry))

AliasRegistry — alias_map() and alias_modifiable_map() now return &BTreeMap references instead of clones.

Safe indexing — replaces direct [..] slicing with .get() + error propagation in ingest_alias_entries and build_object_from_keys, satisfying the crate-wide deny(clippy::indexing_slicing) lint without #[allow] overrides.

Null-tolerant deserialization — custom deserializer for AliasEntry.paths handles the ~97% of real Azure catalog entries where az provider list emits "paths": null.

Scope

All changes are within the azure_policy feature gate. No impact on the core engine, FFI bindings, or other language backends.

[Copilot]

Pull request overview

Optimizes the Azure Policy AliasRegistry to reduce allocations on the load and compile paths, and hardens JSON deserialization against null arrays emitted by az provider list. The compiler now stores Rc<BTreeMap<...>> for alias data so repeated compilations share a single 73K-entry map instead of cloning, and ingest_alias_entries works on borrowed &str slices for short-name derivation.

Changes:

• alias_map() / alias_modifiable_map() return cached Rc<BTreeMap>; compiler holds the Rc instead of an owned clone.
• ingest_alias_entries derives short names via borrowed slices and safe .get()-based indexing, reducing per-alias allocations.
• Adds deserialize_null_as_empty_vec for resourceTypes/aliases/paths/apiVersions, and replaces an #[allow(clippy::indexing_slicing)] block in build_object_from_keys with safe lookups.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/languages/azure_policy/aliases/mod.rs	Adds Rc cache for alias maps, refactors short-name derivation, adds lowercase-key lookup helpers.
src/languages/azure_policy/aliases/types.rs	Adds deserialize_null_as_empty_vec and applies it to four Vec fields.
src/languages/azure_policy/compiler/core.rs	Compiler fields switched from BTreeMap to Rc<BTreeMap>.
src/languages/azure_policy/compiler/mod.rs	compile_*_with_aliases signatures updated to take Rc<BTreeMap>.
src/languages/azure_policy/compiler/effects.rs	Replaces unchecked indexing in build_object_from_keys with safe .get() + error propagation.
examples/regorus/azure_policy.rs	Adjusts example to bind the returned Rc map before iterating.
tests/azure_policy/mod.rs	Makes alias_registry mutable to satisfy new &mut self accessors.

[anakrish]

@copilot review this PR from different perspectives not considered before.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.