Diagnostics

Structured errors, Swift-style ownership messages, borrow notes, and nyra diag --json.

Ownership errors name the callee function, show its parameter types, and suggest &, clone, or move. Full guide: Ownership UX. Proactive snapshots (who owns / who borrows at a line): nyra inspect.

Ownership inspect

When errors are unclear — or while learning — ask the compiler for a binding’s state at a source line:

nyra inspect name --at main.ny:42
nyra check . --ownership-verbose

Compile-time only (no runtime reflection). Rust’s stable toolchain does not ship this. Details: Ownership inspect.

nyra diag

nyra diag . --json

Emits structured JSON for editors and CI. Each entry includes code, label, notes, helps, and end positions (end_line, end_column). Same messages as nyra check / compile errors.

nyra explain

nyra explain E003
nyra explain P001
nyra explain --list

Prints a static explanation for stable diagnostic codes (like rustc --explain). Use after seeing error[E003]: in the terminal or LSP.

Import-related codes: E001 (path not found), E039 (selective import { name } missing or priv), W002 (unused import). See Imports guide → rules.

Ownership diagnostics

error: use of moved value 'user'
  --> main.ny:8:14
   |
 6 |     save(user)
   |          ---- value moved here (into `save`)
 7 |     print(user.name)
   |           ^^^^ value used after move
   |
   = note: `save(user: User)` takes owned `User`
   = help: borrow instead: save(&user)
   = help: or duplicate: save(clone user)

Situation	Typical message	Fix
Use after move into call	`was moved into save()`	`save(&user)` (auto-borrow) or `save(clone user)`
Owned param when borrow expected	Type mismatch on `&T`	Omit `&` — compiler auto-borrows owned values
Explicit move intended	—	`save(move user)` skips auto-borrow
Keep binding after call	Move error	Change callee to `&T` or use `clone`

Common borrow errors

Message	Cause
Use of moved value	Move-type used after move; callee may be named in note
Cannot borrow as mutable	`&mut` aliasing conflict
cannot return reference to local	Dangling `&` return
cannot infer type for 'x'	Add annotation: `let x: T = ...`
expected ',' or '}' between struct literal fields (P006)	Missing comma between literal fields, often after `foo()`	`{ a: f(), b: 1 }` — commas in literals; struct defs use newlines
#[derive(Copy)] on non-Copy struct	Field not Copy (e.g. `string`)
manual free warning	Double-free risk with auto-drop

error: Use of moved value 'a'
  --> main.ny:4:11
   |
 4 |     print(a)
   |           ^