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Don't lint niche optimized variants in enums

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This commit is contained in:
Arvind Mukund 2024-03-09 14:30:01 -08:00
parent b3e6d52e49
commit 08b85a1c53
1 changed files with 18 additions and 25 deletions
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43
compiler/rustc_lint/src/types.rs
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@ -1141,14 +1141,6 @@ pub(crate) fn repr_nullable_ptr<'tcx>(
[var_one, var_two] => match (&var_one.fields.raw[..], &var_two.fields.raw[..]) {
([], [field]) | ([field], []) => field.ty(tcx, args),
([field1], [field2]) => {
// TODO: We pass all the checks here although individual enum variants has
// checks for FFI safety even when niche optimized which needs to be
// suppressed. for types like `Result<PhantomData<()>, E>`, PhantomData has
// it's own lint for FFI which needs to be suppressed: `composed only of
// `PhantomData``. This is true for other custom types as well `struct
// Example;` which emits `this struct has unspecified layout` and suggests to
// add `#[repr(C)]` and when that is done, linter emits `this struct has no
// fields`, all under the `improper_ctypes_definitions` lint group
let ty1 = field1.ty(tcx, args);
let ty2 = field2.ty(tcx, args);
@ -1245,7 +1237,6 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
args: GenericArgsRef<'tcx>,
) -> FfiResult<'tcx> {
use FfiResult::*;
let transparent_with_all_zst_fields = if def.repr().transparent() {
if let Some(field) = transparent_newtype_field(self.cx.tcx, variant) {
// Transparent newtypes have at most one non-ZST field which needs to be checked..
@ -1372,22 +1363,6 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
return FfiSafe;
}
// Check for a repr() attribute to specify the size of the
// discriminant.
if !def.repr().c() && !def.repr().transparent() && def.repr().int.is_none()
{
// Special-case types like `Option<extern fn()>` and `Result<extern fn(), ()>`
if repr_nullable_ptr(self.cx.tcx, self.cx.param_env, ty, self.mode)
.is_none()
{
return FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_enum_repr_reason,
help: Some(fluent::lint_improper_ctypes_enum_repr_help),
};
}
}
if def.is_variant_list_non_exhaustive() && !def.did().is_local() {
return FfiUnsafe {
ty,
@ -1396,6 +1371,24 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
};
}
// Check for a repr() attribute to specify the size of the
// discriminant.
if !def.repr().c() && !def.repr().transparent() && def.repr().int.is_none()
{
// Special-case types like `Option<extern fn()>` and `Result<extern fn(), ()>`
if let Some(ty) =
repr_nullable_ptr(self.cx.tcx, self.cx.param_env, ty, self.mode)
{
return self.check_type_for_ffi(cache, ty);
}
return FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_enum_repr_reason,
help: Some(fluent::lint_improper_ctypes_enum_repr_help),
};
}
// Check the contained variants.
for variant in def.variants() {
let is_non_exhaustive = variant.is_field_list_non_exhaustive();