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derive(SmartPointer): assume pointee from the single generic and better error messages

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This commit is contained in:
Ding Xiang Fei 2024-08-23 21:07:18 +08:00
parent 1a94d839be
commit 39148351bd
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GPG Key ID: 3CD748647EEF6359
5 changed files with 108 additions and 44 deletions
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75
compiler/rustc_builtin_macros/src/deriving/smart_ptr.rs
View File

@ -11,7 +11,6 @@
use rustc_expand::base::{Annotatable, ExtCtxt};
use rustc_span::symbol::{sym, Ident};
use rustc_span::{Span, Symbol};
use smallvec::{smallvec, SmallVec};
use thin_vec::{thin_vec, ThinVec};
macro_rules! path {
@ -68,43 +67,63 @@ pub fn expand_deriving_smart_ptr(
};
// Convert generic parameters (from the struct) into generic args.
let mut pointee_param = None;
let mut multiple_pointee_diag: SmallVec<[_; 2]> = smallvec![];
let self_params = generics
let self_params: Vec<_> = generics
.params
.iter()
.map(|p| match p.kind {
GenericParamKind::Lifetime => GenericArg::Lifetime(cx.lifetime(p.span(), p.ident)),
GenericParamKind::Type { .. } => GenericArg::Type(cx.ty_ident(p.span(), p.ident)),
GenericParamKind::Const { .. } => GenericArg::Const(cx.const_ident(p.span(), p.ident)),
})
.collect();
let type_params: Vec<_> = generics
.params
.iter()
.enumerate()
.map(|(idx, p)| match p.kind {
GenericParamKind::Lifetime => GenericArg::Lifetime(cx.lifetime(p.span(), p.ident)),
GenericParamKind::Type { .. } => {
if p.attrs().iter().any(|attr| attr.has_name(sym::pointee)) {
if pointee_param.is_some() {
multiple_pointee_diag.push(cx.dcx().struct_span_err(
p.span(),
"`SmartPointer` can only admit one type as pointee",
));
} else {
pointee_param = Some(idx);
}
}
GenericArg::Type(cx.ty_ident(p.span(), p.ident))
.filter_map(|(idx, p)| {
if let GenericParamKind::Type { .. } = p.kind {
Some((idx, p.span(), p.attrs().iter().any(|attr| attr.has_name(sym::pointee))))
} else {
None
}
GenericParamKind::Const { .. } => GenericArg::Const(cx.const_ident(p.span(), p.ident)),
})
.collect::<Vec<_>>();
let Some(pointee_param_idx) = pointee_param else {
.collect();
let pointee_param_idx = if type_params.is_empty() {
// `#[derive(SmartPointer)]` requires at least one generic type on the target `struct`
cx.dcx().struct_span_err(
span,
"At least one generic type should be designated as `#[pointee]` in order to derive `SmartPointer` traits",
"`SmartPointer` can only be derived on `struct`s that are generic over at least one type",
).emit();
return;
};
if !multiple_pointee_diag.is_empty() {
for diag in multiple_pointee_diag {
diag.emit();
} else if type_params.len() == 1 {
// Regardless of the only type param being designed as `#[pointee]` or not, we can just use it as such
type_params[0].0
} else {
let mut pointees = type_params
.iter()
.filter_map(|&(idx, span, is_pointee)| is_pointee.then_some((idx, span)))
.fuse();
match (pointees.next(), pointees.next()) {
(Some((idx, _span)), None) => idx,
(None, _) => {
cx.dcx().struct_span_err(
span,
"exactly one generic type parameter must be marked as #[pointee] to derive SmartPointer traits",
).emit();
return;
}
(Some((_, one)), Some((_, another))) => {
cx.dcx()
.struct_span_err(
vec![one, another],
"only one type parameter can be marked as `#[pointee]` when deriving SmartPointer traits",
)
.emit();
return;
}
}
return;
}
};
// Create the type of `self`.
let path = cx.path_all(span, false, vec![name_ident], self_params.clone());

6
tests/ui/deriving/deriving-smart-pointer-expanded.rs
View File

@ -20,3 +20,9 @@ pub struct MyPointer2<'a, Y, Z: MyTrait<T>, #[pointee] T: ?Sized + MyTrait<T>, X
data: &'a mut T,
x: core::marker::PhantomData<X>,
}
#[derive(SmartPointer)]
#[repr(transparent)]
struct MyPointerWithoutPointee<'a, T: ?Sized> {
ptr: &'a T,
}

15
tests/ui/deriving/deriving-smart-pointer-expanded.stdout
View File

@ -42,3 +42,18 @@ impl<'a, Y, Z: MyTrait<T> + MyTrait<__S>, T: ?Sized + MyTrait<T> +
MyTrait<__S>> ::core::ops::CoerceUnsized<MyPointer2<'a, Y, Z, __S, X>> for
MyPointer2<'a, Y, Z, T, X> where Y: MyTrait<T>, Y: MyTrait<__S> {
}
#[repr(transparent)]
struct MyPointerWithoutPointee<'a, T: ?Sized> {
ptr: &'a T,
}
#[automatically_derived]
impl<'a, T: ?Sized + ::core::marker::Unsize<__S>, __S: ?Sized>
::core::ops::DispatchFromDyn<MyPointerWithoutPointee<'a, __S>> for
MyPointerWithoutPointee<'a, T> {
}
#[automatically_derived]
impl<'a, T: ?Sized + ::core::marker::Unsize<__S>, __S: ?Sized>
::core::ops::CoerceUnsized<MyPointerWithoutPointee<'a, __S>> for
MyPointerWithoutPointee<'a, T> {
}

24
tests/ui/deriving/deriving-smart-pointer-neg.rs
View File

@ -9,13 +9,6 @@ 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)]
@ -30,6 +23,23 @@ 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 that are generic over at least one type
#[repr(transparent)]
struct NoGeneric<'a>(&'a u8);
#[derive(SmartPointer)]
//~^ ERROR: exactly one generic type parameter must be marked as #[pointee] to derive SmartPointer traits
#[repr(transparent)]
struct AmbiguousPointee<'a, T1: ?Sized, T2: ?Sized> {
a: (&'a T1, &'a T2),
}
#[derive(SmartPointer)]
#[repr(transparent)]
struct TooManyPointees<'a, #[pointee] A: ?Sized, #[pointee] B: ?Sized>((&'a A, &'a B));
//~^ ERROR: only one type parameter can be marked as `#[pointee]` when deriving SmartPointer traits
#[derive(SmartPointer)]
//~^ ERROR: `SmartPointer` can only be derived on `struct`s with `#[repr(transparent)]`
struct NotTransparent<'a, #[pointee] T: ?Sized> {

32
tests/ui/deriving/deriving-smart-pointer-neg.stderr
View File

@ -6,7 +6,7 @@ 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
error: `SmartPointer` can only be derived on `struct`s with at least one field
--> $DIR/deriving-smart-pointer-neg.rs:12:10
|
LL | #[derive(SmartPointer)]
@ -22,7 +22,7 @@ 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
error: `SmartPointer` can only be derived on `struct`s that are generic over at least one type
--> $DIR/deriving-smart-pointer-neg.rs:26:10
|
LL | #[derive(SmartPointer)]
@ -30,8 +30,22 @@ LL | #[derive(SmartPointer)]
|
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)
error: exactly one generic type parameter must be marked as #[pointee] to derive SmartPointer traits
--> $DIR/deriving-smart-pointer-neg.rs:31:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
|
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)
error: only one type parameter can be marked as `#[pointee]` when deriving SmartPointer traits
--> $DIR/deriving-smart-pointer-neg.rs:40:39
|
LL | struct TooManyPointees<'a, #[pointee] A: ?Sized, #[pointee] B: ?Sized>((&'a A, &'a B));
| ^ ^
error: `SmartPointer` can only be derived on `struct`s with `#[repr(transparent)]`
--> $DIR/deriving-smart-pointer-neg.rs:33:10
--> $DIR/deriving-smart-pointer-neg.rs:43:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
@ -39,13 +53,13 @@ LL | #[derive(SmartPointer)]
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)
error: `derive(SmartPointer)` requires T to be marked `?Sized`
--> $DIR/deriving-smart-pointer-neg.rs:41:36
--> $DIR/deriving-smart-pointer-neg.rs:51:36
|
LL | struct NoMaybeSized<'a, #[pointee] T> {
| ^
error[E0392]: lifetime parameter `'a` is never used
--> $DIR/deriving-smart-pointer-neg.rs:22:16
--> $DIR/deriving-smart-pointer-neg.rs:15:16
|
LL | struct NoField<'a, #[pointee] T: ?Sized> {}
| ^^ unused lifetime parameter
@ -53,7 +67,7 @@ LL | struct NoField<'a, #[pointee] T: ?Sized> {}
= 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:22:31
--> $DIR/deriving-smart-pointer-neg.rs:15:31
|
LL | struct NoField<'a, #[pointee] T: ?Sized> {}
| ^ unused type parameter
@ -61,7 +75,7 @@ LL | struct NoField<'a, #[pointee] T: ?Sized> {}
= 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:29:20
--> $DIR/deriving-smart-pointer-neg.rs:22:20
|
LL | struct NoFieldUnit<'a, #[pointee] T: ?Sized>();
| ^^ unused lifetime parameter
@ -69,13 +83,13 @@ LL | struct NoFieldUnit<'a, #[pointee] T: ?Sized>();
= 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:29:35
--> $DIR/deriving-smart-pointer-neg.rs:22:35
|
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 10 previous errors
error: aborting due to 12 previous errors
For more information about this error, try `rustc --explain E0392`.