bjoernager/rust
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On E0277 be clearer about implicit Sized bounds on type params and assoc types

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```
error[E0277]: the size for values of type `[i32]` cannot be known at compilation time
   --> f100.rs:2:33
    |
2   |     let _ = std::mem::size_of::<[i32]>();
    |                                 ^^^^^ doesn't have a size known at compile-time
    |
    = help: the trait `Sized` is not implemented for `[i32]`
note: required by an implicit `Sized` bound in `std::mem::size_of`
   --> /home/gh-estebank/rust/library/core/src/mem/mod.rs:312:22
    |
312 | pub const fn size_of<T>() -> usize {
    |                      ^ required by the implicit `Sized` requirement on this bound in `size_of`
```

Fix #120178.
This commit is contained in:
Esteban Küber 2024-01-24 21:29:15 +00:00
parent 11f32b73e0
commit c4c22b0d52
48 changed files with 232 additions and 223 deletions
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14
compiler/rustc_hir_analysis/src/astconv/bounds.rs
View file

@ -28,6 +28,7 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
let tcx = self.tcx();
let sized_def_id = tcx.lang_items().sized_trait();
let mut seen_negative_sized_bound = false;
let mut seen_positive_sized_bound = false;
// Try to find an unbound in bounds.
let mut unbounds: SmallVec<[_; 1]> = SmallVec::new();
@ -45,6 +46,13 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
seen_negative_sized_bound = true;
}
}
hir::TraitBoundModifier::None => {
if let Some(sized_def_id) = sized_def_id
&& ptr.trait_ref.path.res == Res::Def(DefKind::Trait, sized_def_id)
{
seen_positive_sized_bound = true;
}
}
_ => {}
}
}
@ -82,11 +90,11 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
);
}
if seen_sized_unbound || seen_negative_sized_bound {
// There was in fact a `?Sized` or `!Sized` bound;
if seen_sized_unbound || seen_negative_sized_bound || seen_positive_sized_bound {
// There was in fact a `?Sized`, `!Sized` or explicit `Sized` bound;
// we don't need to do anything.
} else if sized_def_id.is_some() {
// There was no `?Sized` or `!Sized` bound;
// There was no `?Sized`, `!Sized` or explicit `Sized` bound;
// add `Sized` if it's available.
bounds.push_sized(tcx, self_ty, span);
}