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Rollup merge of #81243 - osa1:fix_80742_2, r=RalfJung

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mir: Improve size_of handling when arg is unsized

As discussed on Zulip with `@RalfJung.`
This commit is contained in:
Jonas Schievink 2021-01-23 20:16:04 +01:00 committed by GitHub
commit 3a3470bf04
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3 changed files with 35 additions and 3 deletions
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3
compiler/rustc_middle/src/mir/interpret/error.rs
View File

@ -127,6 +127,8 @@ pub enum InvalidProgramInfo<'tcx> {
Layout(layout::LayoutError<'tcx>),
/// An invalid transmute happened.
TransmuteSizeDiff(Ty<'tcx>, Ty<'tcx>),
/// SizeOf of unsized type was requested.
SizeOfUnsizedType(Ty<'tcx>),
}
impl fmt::Display for InvalidProgramInfo<'_> {
@ -144,6 +146,7 @@ impl fmt::Display for InvalidProgramInfo<'_> {
"transmuting `{}` to `{}` is not possible, because these types do not have the same size",
from_ty, to_ty
),
SizeOfUnsizedType(ty) => write!(f, "size_of called on unsized type `{}`", ty),
}
}
}

1
compiler/rustc_mir/src/interpret/step.rs
View File

@ -270,6 +270,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
self.frame().current_span(),
&format!("SizeOf nullary MIR operator called for unsized type {}", ty),
);
throw_inval!(SizeOfUnsizedType(ty));
}
self.write_scalar(Scalar::from_machine_usize(layout.size.bytes(), self), dest)?;
}

34
src/test/ui/mir/issue-80742.stderr
View File

@ -1,3 +1,17 @@
error[E0080]: evaluation of constant value failed
--> $SRC_DIR/core/src/mem/mod.rs:LL:COL
|
LL | intrinsics::size_of::<T>()
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| size_of called on unsized type `dyn Debug`
| inside `std::mem::size_of::<dyn Debug>` at $SRC_DIR/core/src/mem/mod.rs:LL:COL
|
::: $DIR/issue-80742.rs:23:10
|
LL | [u8; size_of::<T>() + 1]: ,
| -------------- inside `Inline::<dyn Debug>::{constant#0}` at $DIR/issue-80742.rs:23:10
error[E0599]: no function or associated item named `new` found for struct `Inline<dyn Debug>` in the current scope
--> $DIR/issue-80742.rs:31:36
|
@ -21,6 +35,20 @@ LL | pub trait Debug {
= note: the method `new` exists but the following trait bounds were not satisfied:
`dyn Debug: Sized`
error[E0080]: evaluation of constant value failed
--> $SRC_DIR/core/src/mem/mod.rs:LL:COL
|
LL | intrinsics::size_of::<T>()
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| size_of called on unsized type `dyn Debug`
| inside `std::mem::size_of::<dyn Debug>` at $SRC_DIR/core/src/mem/mod.rs:LL:COL
|
::: $DIR/issue-80742.rs:15:10
|
LL | [u8; size_of::<T>() + 1]: ,
| -------------- inside `Inline::<dyn Debug>::{constant#0}` at $DIR/issue-80742.rs:15:10
error[E0277]: the size for values of type `dyn Debug` cannot be known at compilation time
--> $DIR/issue-80742.rs:31:15
|
@ -36,7 +64,7 @@ help: consider relaxing the implicit `Sized` restriction
LL | struct Inline<T: ?Sized>
| ^^^^^^^^
error: aborting due to 2 previous errors
error: aborting due to 4 previous errors
Some errors have detailed explanations: E0277, E0599.
For more information about an error, try `rustc --explain E0277`.
Some errors have detailed explanations: E0080, E0277, E0599.
For more information about an error, try `rustc --explain E0080`.