Skip to content

fix(rt): handle zero-sized function types in decode and ZST recognition #813

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
automergerpr-permission-manager merged 4 commits into from
Mar 28, 2026
Merged

fix(rt): handle zero-sized function types in decode and ZST recognition #813

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
554ee33
test(rt): expose closure zero-sized decode thunk via terminate-on-thunk
Stevengre Mar 23, 2026
ea760c0
fix(rt): decode zero-sized function types and recognize them as ZSTs
Stevengre Mar 23, 2026
3aa012d
chore(test): remove closure-staged expected output
Stevengre Mar 26, 2026
07b03c2
Merge branch 'master' into jh/zero-sized-decode
dkcumming Mar 27, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 3 additions & 0 deletions kmir/src/kmir/kdist/mir-semantics/rt/data.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1921,6 +1921,9 @@ Zero-sized types can be decoded trivially into their respective representation.
// zero-sized array
rule <k> #decodeConstant(constantKindZeroSized, _TY, typeInfoArrayType(_, _))
=> Range(.List) ... </k>
// zero-sized function item (e.g., closures without captures)
rule <k> #decodeConstant(constantKindZeroSized, _TY, typeInfoFunType(_))
=> Aggregate(variantIdx(0), .List) ... </k>
```

Allocated constants of reference type with a single provenance map entry are decoded as references
Expand Down
5 changes: 3 additions & 2 deletions kmir/src/kmir/kdist/mir-semantics/rt/types.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -348,8 +348,9 @@ Slices, `str`s and dynamic types require it, and any `Ty` that `is_sized` does
rule #zeroSizedType(typeInfoTupleType(.Tys, _)) => true
rule #zeroSizedType(typeInfoStructType(_, _, .Tys, _)) => true
rule #zeroSizedType(typeInfoVoidType) => true
// FIXME: Only unit tuples, empty structs, and void are recognized here; other
// zero-sized types (e.g. single-variant enums, function or closure items,
rule #zeroSizedType(typeInfoFunType(_)) => true
Copy link
Copy Markdown

@chatgpt-codex-connector chatgpt-codex-connector bot Mar 26, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

P1 Badge Exclude invalid lookup sentinel from ZST function rule

#zeroSizedType(typeInfoFunType(_)) => true now also matches the sentinel returned by lookupTy on missing entries (typeInfoFunType(" ** INVALID LOOKUP CALL **") in rt/value.md), so unresolved type IDs are silently treated as zero-sized. That changes behavior in places that gate on #zeroSizedType (notably pointer projection compatibility in #pointeeProjection and zero-sized local materialization in rvalueRef), allowing execution to proceed with fabricated ZST behavior instead of surfacing a missing-type-table condition; this can corrupt proof behavior when type extraction is incomplete.

Useful? React with 👍 / 👎.

// FIXME: Only unit tuples, empty structs, void, and function items are
// recognized here; other zero-sized types (e.g. single-variant enums,
// newtype wrappers around ZSTs) still fall through because we do not consult
// the layout metadata yet. Update once we rely on machineSize(0).
rule #zeroSizedType(_) => false [owise]
Expand Down
6 changes: 5 additions & 1 deletion kmir/src/tests/integration/test_integration.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,9 @@
'iter-eq-copied-take-dereftruncate': ['repro'],
'spl-multisig-iter-eq-copied-next': ['repro'],
}
PROVE_TERMINATE_ON_THUNK = [
'closure-staged',
]
PROVE_SHOW_SPECS = [
'local-raw-fail',
'interior-mut-fail',
Expand Down Expand Up @@ -87,7 +90,8 @@ def test_prove(rs_file: Path, kmir: KMIR, update_expected_output: bool) -> None:
if update_expected_output and not should_show:
pytest.skip()

prove_opts = ProveOpts(rs_file, smir=is_smir)
should_terminate_on_thunk = rs_file.stem in PROVE_TERMINATE_ON_THUNK
prove_opts = ProveOpts(rs_file, smir=is_smir, terminate_on_thunk=should_terminate_on_thunk)
printer = PrettyPrinter(kmir.definition)
cterm_show = CTermShow(printer.print)

Expand Down
Loading