Enum BackendWalkError 

pub enum BackendWalkError {
    MissingInput {
        op_type: String,
        input_name: String,
    },
    OutputArityMismatch {
        op_type: String,
        produced: usize,
        declared: usize,
    },
    UnknownOpType(String),
    MissingExecuteOutput {
        op_type: String,
        output_name: String,
    },
    WireMaterializeFailed {
        type_hash: u64,
        reason: String,
    },
}

Failures the default walker surfaces when handed a malformed GraphProto body or when a Backend::execute impl violates its output-name contract. Required From bound on Backend::Error makes the walker fail with a typed error instead of panic!-ing on peer-supplied or buggy input.

Variants

MissingInput

A NodeProto references an input value not in the running environment. The graph either uses a value the caller didn’t bind OR an upstream node failed to populate one of its declared outputs.

Fields

op_type: String

op_type of the consuming node.

input_name: String

Name of the missing input value.

OutputArityMismatch

A per-op method produced a different number of outputs than the consuming NodeProto declares. Indicates a compiler or graph-builder bug.

Fields

op_type: String

op_type of the node.

produced: usize

Number of outputs the per-op method produced.

declared: usize

Number of outputs the graph declares.

UnknownOpType(String)

op_type is not one of bb_ir::tensor_primitives::TENSOR_PRIMITIVES_OPS. Backends that use the default per-op walker must keep graphs to primitives only. The wire path can hit this when an adversarial peer ships a BackendSubgraph_* carrier whose body references an extension op.

MissingExecuteOutput

A Backend::execute impl returned successfully but did not populate the declared output output_name in the result map. Indicates a Backend impl bug — execute MUST honor the graph’s output names.

Fields

op_type: String

op_type of the single-node graph that was executed.

output_name: String

Output name the graph declared but execute omitted.

WireMaterializeFailed

Default crate::contracts::Backend::materialize_from_wire failed before reaching the backend: no registered decoder, the decoder rejected the bytes, or the decoded carrier was not assignable to Self::Tensor. Backends overriding materialize_from_wire never surface this — they emit their own typed error.

Fields

type_hash: u64

type_hash the inbound SlotFill advertised.

reason: String

Why the default path could not produce a Self::Tensor.

Trait Implementations

impl Clone for BackendWalkError

fn clone(&self) -> BackendWalkError

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BackendWalkError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for BackendWalkError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for BackendWalkError

impl Error for BackendWalkError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for BackendWalkError

fn eq(&self, other: &BackendWalkError) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for BackendWalkError