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| author | Michael Goulet <michael@errs.io> | 2025-01-08 00:28:47 +0000 |
|---|---|---|
| committer | Michael Goulet <michael@errs.io> | 2025-01-08 00:28:47 +0000 |
| commit | 3c3186148e4a66a507e606f191c35ed49d873b08 (patch) | |
| tree | 9ffe97bddbaed9c6bc1b684c75dfdda1f00b0e3c /compiler/rustc_hir_analysis | |
| parent | ad211ced81509462cdfe4c29ed10f97279a0acae (diff) | |
| download | rust-3c3186148e4a66a507e606f191c35ed49d873b08.tar.gz rust-3c3186148e4a66a507e606f191c35ed49d873b08.zip | |
Don't allow transmuting ZSTs in dispatch_from_dyn impl
Diffstat (limited to 'compiler/rustc_hir_analysis')
| -rw-r--r-- | compiler/rustc_hir_analysis/messages.ftl | 2 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/coherence/builtin.rs | 17 |
2 files changed, 14 insertions, 5 deletions
diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl index 0c3ed9b5c60..d7ab6eca84b 100644 --- a/compiler/rustc_hir_analysis/messages.ftl +++ b/compiler/rustc_hir_analysis/messages.ftl @@ -135,7 +135,7 @@ hir_analysis_dispatch_from_dyn_multi = implementing the `DispatchFromDyn` trait hir_analysis_dispatch_from_dyn_repr = structs implementing `DispatchFromDyn` may not have `#[repr(packed)]` or `#[repr(C)]` -hir_analysis_dispatch_from_dyn_zst = the trait `DispatchFromDyn` may only be implemented for structs containing the field being coerced, ZST fields with 1 byte alignment, and nothing else +hir_analysis_dispatch_from_dyn_zst = the trait `DispatchFromDyn` may only be implemented for structs containing the field being coerced, ZST fields with 1 byte alignment that don't mention type/const generics, and nothing else .note = extra field `{$name}` of type `{$ty}` is not allowed hir_analysis_drop_impl_negative = negative `Drop` impls are not supported diff --git a/compiler/rustc_hir_analysis/src/coherence/builtin.rs b/compiler/rustc_hir_analysis/src/coherence/builtin.rs index 3b98f358b1e..760c09a1e72 100644 --- a/compiler/rustc_hir_analysis/src/coherence/builtin.rs +++ b/compiler/rustc_hir_analysis/src/coherence/builtin.rs @@ -259,16 +259,25 @@ fn visit_implementation_of_dispatch_from_dyn(checker: &Checker<'_>) -> Result<() let coerced_fields = fields .iter() .filter(|field| { + // Ignore PhantomData fields + if tcx.type_of(field.did).instantiate_identity().is_phantom_data() { + return false; + } + let ty_a = field.ty(tcx, args_a); let ty_b = field.ty(tcx, args_b); + // Allow 1-ZSTs that don't mention type params. + // + // Allowing type params here would allow us to possibly transmute + // between ZSTs, which may be used to create library unsoundness. if let Ok(layout) = tcx.layout_of(infcx.typing_env(param_env).as_query_input(ty_a)) + && layout.is_1zst() + && !ty_a.has_non_region_param() { - if layout.is_1zst() { - // ignore 1-ZST fields - return false; - } + // ignore 1-ZST fields + return false; } if ty_a == ty_b { |