check_version_match

void check_version_match(const int & live, int saved_version, int op_name, int input_idx)

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Verify that a saved tensor's version counter has not advanced.

Compares the current version() of the tensor referenced by live against saved_version. When they differ the saved data has been mutated in place since it was stashed for backward, which would silently corrupt the gradient — so a VersionMismatch is raised naming the op and input that owns the broken contract.

Parameters

liveconst std::weak_ptr<TensorImpl>&

Weak reference to the still-live tensor. When the referent has been destroyed the check is skipped (no harm if it cannot be mutated after the fact).

saved_versionstd::int64_t

Version counter value captured when the tensor was saved.

op_namestd::string_view

Name of the op for diagnostic messages (e.g. "matmul").

input_idxstd::size_t

Zero-based index of the offending input within op_name.

Raises

VersionMismatch

The live counter differs from saved_version and the safety override (is_mutation_on_saved_allowed) is false.