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lint/ctypes: only try normalize

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Now that this lint runs on any external-ABI fn-ptr, normalization won't
always succeed, so use `try_normalize_erasing_regions` instead.

Signed-off-by: David Wood <david@davidtw.co>
This commit is contained in:
David Wood 2023-07-21 15:42:25 +01:00
parent c06b2b9117
commit 09434a2575
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2 changed files with 21 additions and 12 deletions
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21
compiler/rustc_lint/src/types.rs
View File

@ -966,12 +966,12 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
args: GenericArgsRef<'tcx>,
) -> FfiResult<'tcx> {
let field_ty = field.ty(self.cx.tcx, args);
if field_ty.has_opaque_types() {
self.check_type_for_ffi(cache, field_ty)
} else {
let field_ty = self.cx.tcx.normalize_erasing_regions(self.cx.param_env, field_ty);
self.check_type_for_ffi(cache, field_ty)
}
let field_ty = self
.cx
.tcx
.try_normalize_erasing_regions(self.cx.param_env, field_ty)
.unwrap_or(field_ty);
self.check_type_for_ffi(cache, field_ty)
}
/// Checks if the given `VariantDef`'s field types are "ffi-safe".
@ -1320,7 +1320,8 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
if let Some(ty) = self
.cx
.tcx
.normalize_erasing_regions(self.cx.param_env, ty)
.try_normalize_erasing_regions(self.cx.param_env, ty)
.unwrap_or(ty)
.visit_with(&mut ProhibitOpaqueTypes)
.break_value()
{
@ -1338,16 +1339,12 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
is_static: bool,
is_return_type: bool,
) {
// We have to check for opaque types before `normalize_erasing_regions`,
// which will replace opaque types with their underlying concrete type.
if self.check_for_opaque_ty(sp, ty) {
// We've already emitted an error due to an opaque type.
return;
}
// it is only OK to use this function because extern fns cannot have
// any generic types right now:
let ty = self.cx.tcx.normalize_erasing_regions(self.cx.param_env, ty);
let ty = self.cx.tcx.try_normalize_erasing_regions(self.cx.param_env, ty).unwrap_or(ty);
// C doesn't really support passing arrays by value - the only way to pass an array by value
// is through a struct. So, first test that the top level isn't an array, and then

12
tests/ui/lint/lint-ctypes-113900.rs Normal file
View File

@ -0,0 +1,12 @@
// check-pass
// Extending `improper_ctypes` to check external-ABI fn-ptrs means that it can encounter
// projections which cannot be normalized - unsurprisingly, this shouldn't crash the compiler.
trait Bar {
type Assoc;
}
type Foo<T> = extern "C" fn() -> <T as Bar>::Assoc;
fn main() {}