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Unrolled build for rust-lang#127283
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Rollup merge of rust-lang#127283 - dingxiangfei2009:check-repr-transparent, r=davidtwco

Reject SmartPointer constructions not serving the purpose

Tracking issue: rust-lang#123430

With this PR we will reject a row of malformed `SmartPointer` implementor candidates.

cc `@Darksonn` `@davidtwco` for context.
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rust-timer authored Jul 4, 2024
2 parents 9f877c9 + 0b4edb2 commit 4222111
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Showing 6 changed files with 159 additions and 4 deletions.
39 changes: 36 additions & 3 deletions compiler/rustc_builtin_macros/src/deriving/smart_ptr.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,9 @@ use std::mem::swap;
use ast::HasAttrs;
use rustc_ast::{
self as ast, GenericArg, GenericBound, GenericParamKind, ItemKind, MetaItem,
TraitBoundModifiers,
TraitBoundModifiers, VariantData,
};
use rustc_attr as attr;
use rustc_expand::base::{Annotatable, ExtCtxt};
use rustc_span::symbol::{sym, Ident};
use rustc_span::Span;
Expand All @@ -24,11 +25,43 @@ pub fn expand_deriving_smart_ptr(
_is_const: bool,
) {
let (name_ident, generics) = if let Annotatable::Item(aitem) = item
&& let ItemKind::Struct(_, g) = &aitem.kind
&& let ItemKind::Struct(struct_data, g) = &aitem.kind
{
let is_transparent = aitem.attrs.iter().any(|attr| {
attr::find_repr_attrs(cx.sess, attr)
.into_iter()
.any(|r| matches!(r, attr::ReprTransparent))
});
if !is_transparent {
cx.dcx()
.struct_span_err(
span,
"`SmartPointer` can only be derived on `struct`s with `#[repr(transparent)]`",
)
.emit();
return;
}
if !matches!(
struct_data,
VariantData::Struct { fields, recovered: _ } | VariantData::Tuple(fields, _)
if !fields.is_empty())
{
cx.dcx()
.struct_span_err(
span,
"`SmartPointer` can only be derived on `struct`s with at least one field",
)
.emit();
return;
}
(aitem.ident, g)
} else {
cx.dcx().struct_span_err(span, "`SmartPointer` can only be derived on `struct`s").emit();
cx.dcx()
.struct_span_err(
span,
"`SmartPointer` can only be derived on `struct`s with `#[repr(transparent)]`",
)
.emit();
return;
};

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45 changes: 45 additions & 0 deletions tests/ui/deriving/deriving-smart-pointer-neg.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,45 @@
#![feature(derive_smart_pointer, arbitrary_self_types)]

use std::marker::SmartPointer;

#[derive(SmartPointer)]
//~^ ERROR: `SmartPointer` can only be derived on `struct`s with `#[repr(transparent)]`
enum NotStruct<'a, T: ?Sized> {
Variant(&'a T),
}

#[derive(SmartPointer)]
//~^ ERROR: At least one generic type should be designated as `#[pointee]` in order to derive `SmartPointer` traits
#[repr(transparent)]
struct NoPointee<'a, T: ?Sized> {
ptr: &'a T,
}

#[derive(SmartPointer)]
//~^ ERROR: `SmartPointer` can only be derived on `struct`s with at least one field
#[repr(transparent)]
struct NoField<'a, #[pointee] T: ?Sized> {}
//~^ ERROR: lifetime parameter `'a` is never used
//~| ERROR: type parameter `T` is never used

#[derive(SmartPointer)]
//~^ ERROR: `SmartPointer` can only be derived on `struct`s with at least one field
#[repr(transparent)]
struct NoFieldUnit<'a, #[pointee] T: ?Sized>();
//~^ ERROR: lifetime parameter `'a` is never used
//~| ERROR: type parameter `T` is never used

#[derive(SmartPointer)]
//~^ ERROR: `SmartPointer` can only be derived on `struct`s with `#[repr(transparent)]`
struct NotTransparent<'a, #[pointee] T: ?Sized> {
ptr: &'a T,
}

// However, reordering attributes should work nevertheless.
#[repr(transparent)]
#[derive(SmartPointer)]
struct ThisIsAPossibleSmartPointer<'a, #[pointee] T: ?Sized> {
ptr: &'a T,
}

fn main() {}
75 changes: 75 additions & 0 deletions tests/ui/deriving/deriving-smart-pointer-neg.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,75 @@
error: `SmartPointer` can only be derived on `struct`s with `#[repr(transparent)]`
--> $DIR/deriving-smart-pointer-neg.rs:5:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
|
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)

error: At least one generic type should be designated as `#[pointee]` in order to derive `SmartPointer` traits
--> $DIR/deriving-smart-pointer-neg.rs:11:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
|
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)

error: `SmartPointer` can only be derived on `struct`s with at least one field
--> $DIR/deriving-smart-pointer-neg.rs:18:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
|
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)

error: `SmartPointer` can only be derived on `struct`s with at least one field
--> $DIR/deriving-smart-pointer-neg.rs:25:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
|
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)

error: `SmartPointer` can only be derived on `struct`s with `#[repr(transparent)]`
--> $DIR/deriving-smart-pointer-neg.rs:32:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
|
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0392]: lifetime parameter `'a` is never used
--> $DIR/deriving-smart-pointer-neg.rs:21:16
|
LL | struct NoField<'a, #[pointee] T: ?Sized> {}
| ^^ unused lifetime parameter
|
= help: consider removing `'a`, referring to it in a field, or using a marker such as `PhantomData`

error[E0392]: type parameter `T` is never used
--> $DIR/deriving-smart-pointer-neg.rs:21:31
|
LL | struct NoField<'a, #[pointee] T: ?Sized> {}
| ^ unused type parameter
|
= help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`

error[E0392]: lifetime parameter `'a` is never used
--> $DIR/deriving-smart-pointer-neg.rs:28:20
|
LL | struct NoFieldUnit<'a, #[pointee] T: ?Sized>();
| ^^ unused lifetime parameter
|
= help: consider removing `'a`, referring to it in a field, or using a marker such as `PhantomData`

error[E0392]: type parameter `T` is never used
--> $DIR/deriving-smart-pointer-neg.rs:28:35
|
LL | struct NoFieldUnit<'a, #[pointee] T: ?Sized>();
| ^ unused type parameter
|
= help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`

error: aborting due to 9 previous errors

For more information about this error, try `rustc --explain E0392`.
1 change: 1 addition & 0 deletions tests/ui/deriving/deriving-smart-pointer.rs
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
use std::marker::SmartPointer;

#[derive(SmartPointer)]
#[repr(transparent)]
struct MyPointer<'a, #[pointee] T: ?Sized> {
ptr: &'a T,
}
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
use std::marker::SmartPointer; //~ ERROR use of unstable library feature 'derive_smart_pointer'

#[derive(SmartPointer)] //~ ERROR use of unstable library feature 'derive_smart_pointer'
#[repr(transparent)]
struct MyPointer<'a, #[pointee] T: ?Sized> {
//~^ ERROR the `#[pointee]` attribute is an experimental feature
ptr: &'a T,
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ LL | #[derive(SmartPointer)]
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0658]: the `#[pointee]` attribute is an experimental feature
--> $DIR/feature-gate-derive-smart-pointer.rs:4:22
--> $DIR/feature-gate-derive-smart-pointer.rs:5:22
|
LL | struct MyPointer<'a, #[pointee] T: ?Sized> {
| ^^^^^^^^^^
Expand Down

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