JuliaDiff / JuliaDiff/ChainRulesCore.jl
Get rid of `MethodError: no method matching iterate(::Nothing)`
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- Dominant language
- Julia
- Stars
- 267
- Forks
- 66
- PR merge metrics
- No merged PRs in 30d
Description
This frequent error happens because of the default dispatches
frule(ȧrgs, f, ::Vararg{Any}) = nothing
rrule(::Any, ::Vararg{Any}) = nothing
so when no rrule is defined, nothing is returned.
Unfortunately, it is hard to catch because the computations with nothing can go on for a while before erroring.
I wonder if removing these default dispatches would break something badly?
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by examining the default frule and rrule dispatches shown in the issue and tracing how their nothing result is consumed. Determine whether removing them breaks existing behavior, then define the intended replacement behavior and add coverage for calls without a matching rule; the issue does not name specific files or tests.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- julia
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 30/100