FAQ

Does the Rust parser require a C toolchain?

No. cargo build -p roup builds the complete parser as safe Rust. The optional roup-capi package and C++ compatibility adapters are separate consumers.

What does an exact specification version mean?

It is an introduction ceiling. Syntax first standardized after the selected version is rejected. Standardized older syntax remains accepted even if a newer specification deprecated or removed it, which keeps maintained legacy code parseable.

Are spelling aliases preserved?

No. Standard aliases are accepted and canonicalized into one semantic AST shape. Version compatibility is computed from typed parser provenance. The checked name span can still select the exact spelling in the original source.

What happens to unsupported host-language expressions?

Parsing fails with an invalid-expression diagnostic. A successful result always contains a classified host-expression tree.

Where is unsafe Rust used?

Only the optional C ABI’s audited byte-copy boundary contains unsafe code. The root parser forbids unsafe Rust, and all other ABI modules deny it.

How are C ABI objects owned?

Parser, directive, child-node, and diagnostic objects share one server-owned generational arena. Each padding-free two-word handle identifies exactly one stored object, whose internal variant is checked before every access or release. Each successful handle is released exactly once with its matching release operation. Invalid, stale, fabricated, and wrong-kind handles are hard errors.

Why is there no clause payload string function?

Clause payloads are structured data rather than one scalar value. Consumers query typed fields and must report an unsupported conversion directly.