WebAssembly / WebAssembly/binaryen
Missed opportunity to merge private types into public supertypes
Nobody has claimed this yet.
- Dominant language
- WebAssembly
- Stars
- 8.6k
- Forks
- 885
- Avg merge
- 1d 19h
- Merged PRs (30d)
- 69
Description
MergeTypes currently treats all public types as terminal DFA states, meaning they have no successors. This can prevent private subtypes of public types from being merged into the public supertypes because their states have different behavior.
The types in this test case are currently not merged, but they should be:
(module
(type $public (sub (struct (field (ref null $public)))))
(type $sub (sub $public (struct (field (ref null $public)))))
(global $g (export "g") (ref null $public) (ref.null none))
(func $test
(local (ref $public))
(local (ref $sub))
)
)
Contributor guide
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 locating MergeTypes in Binaryen and reproduce the issue with the WebAssembly module in the report. Trace how public types are treated as terminal DFA states, then verify the private subtype and public supertype are merged for this case. Done means the supplied test case merges the types without regressing existing behavior.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- wasm
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100