Attempt to implement support for self-referential union types - #3419
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erickt wants to merge 2 commits into
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Attempt to implement support for self-referential union types#3419erickt wants to merge 2 commits into
erickt wants to merge 2 commits into
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Update safe_resolve_type to use .and_then(|t| t.kind().as_type()) and convert panicking resolve_type calls across ty.rs and enum_ty.rs to safe_resolve_type. This prevents compiler panics when item IDs are temporarily loaned out during AST graph traversal (with_loaned_item) or when IDs point to non-type items. Test: cargo test -p bindgen-tests TAG=agy CONV=49e4437e-d358-4213-bb5a-8478173dda33
Early return None in CompInfo::layout for uninstantiated C++ template definitions (!self.template_params.is_empty()), avoiding infinite layout recursion on variadic template unions. In CompInfo::is_rust_union, check ctx.uses_any_template_parameters during codegen, emitting struct + __BindgenUnionField<T> wrappers for unconstrained generic template union fields to prevent Rust compiler E0740 errors. Test: cargo test -p bindgen-tests TAG=agy CONV=49e4437e-d358-4213-bb5a-8478173dda33
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In llvm/llvm-project#185449, LLVM's libc++ changed a header to use a recursive self-referential type, which looks approximately like:
This code caused bindgen to panic. The problem seems to be that bindgen can't handle the recursive self-referential union. Digging into the code, it seems that when this type is being parsed,
with_loaned_itemremoves the type from the context. Later on, when parsing theCompKind::Union,CompInfo::layoutwould callresolve_typeon an item that was loaned out, so it panics. This bug was filed in #3397.I've attempted to fix this bug with the help of Gemini agent, and it seems that we might be able to swap out
resolve_typewithsafe_resolve_typein a few locations to get it to stop erroring out. This seems to make sense as best as I understand this situation, although there may be a chance that returningNonein these callsites might be incorrect. But I couldn't find a counter example that shows incorrect code.Fixes #3397