Skip to content

Commit

Permalink
improve generic Drop error messages
Browse files Browse the repository at this point in the history 
- Use the span of the predicate
- Use the def's description instead of "struct/enum" (notably incorrect
  for unions)
- Align formatting with other error messages
  • Loading branch information
@euclio
euclio committed Jan 3, 2020
1 parent 0a58f58 commit e589358
Show file tree
Hide file tree
Showing 6 changed files with 110 additions and 69 deletions.
34 changes: 18 additions & 16 deletions src/librustc_typeck/check/dropck.rs
View file
Expand Up @@ -47,7 +47,6 @@ pub fn check_drop_impl(tcx: TyCtxt<'_>, drop_impl_did: DefId) -> Result<(), Erro

ensure_drop_predicates_are_implied_by_item_defn(
tcx,
drop_impl_did,
dtor_predicates,
adt_def.did,
self_to_impl_substs,
Expand Down Expand Up @@ -95,16 +94,23 @@ fn ensure_drop_params_and_item_params_correspond<'tcx>(
}
Err(_) => {
let item_span = tcx.def_span(self_type_did);
let self_descr = tcx
.def_kind(self_type_did)
.map(|kind| kind.descr(self_type_did))
.unwrap_or("type");
struct_span_err!(
tcx.sess,
drop_impl_span,
E0366,
"Implementations of Drop cannot be specialized"
"`Drop` impls cannot be specialized"
)
.span_note(
item_span,
"Use same sequence of generic type and region \
parameters that is on the struct/enum definition",
&format!(
"use the same sequence of generic type, lifetime and const parameters \
as the {} definition",
self_descr,
),
)
.emit();
return Err(ErrorReported);
Expand Down Expand Up @@ -143,7 +149,6 @@ fn ensure_drop_params_and_item_params_correspond<'tcx>(
/// implied by assuming the predicates attached to self_type_did.
fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
tcx: TyCtxt<'tcx>,
drop_impl_did: DefId,
dtor_predicates: ty::GenericPredicates<'tcx>,
self_type_did: DefId,
self_to_impl_substs: SubstsRef<'tcx>,
Expand Down Expand Up @@ -187,8 +192,6 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(

let self_type_hir_id = tcx.hir().as_local_hir_id(self_type_did).unwrap();

let drop_impl_span = tcx.def_span(drop_impl_did);

// We can assume the predicates attached to struct/enum definition
// hold.
let generic_assumptions = tcx.predicates_of(self_type_did);
Expand All @@ -205,7 +208,7 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
// just to look for all the predicates directly.

assert_eq!(dtor_predicates.parent, None);
for (predicate, _) in dtor_predicates.predicates {
for (predicate, predicate_sp) in dtor_predicates.predicates {
// (We do not need to worry about deep analysis of type
// expressions etc because the Drop impls are already forced
// to take on a structure that is roughly an alpha-renaming of
Expand Down Expand Up @@ -241,18 +244,17 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(

if !assumptions_in_impl_context.iter().any(predicate_matches_closure) {
let item_span = tcx.hir().span(self_type_hir_id);
let self_descr =
tcx.def_kind(self_type_did).map(|kind| kind.descr(self_type_did)).unwrap_or("type");
struct_span_err!(
tcx.sess,
drop_impl_span,
*predicate_sp,
E0367,
"The requirement `{}` is added only by the Drop impl.",
predicate
)
.span_note(
item_span,
"The same requirement must be part of \
the struct/enum definition",
"`Drop` impl requires `{}` but the {} it is implemented for does not",
predicate,
self_descr,
)
.span_note(item_span, "the implementor must specify the same requirement")
.emit();
result = Err(ErrorReported);
}
Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/issues/issue-17959.rs
View file
Expand Up @@ -9,7 +9,7 @@ struct G<T: ?Sized> {
}

impl<T> Drop for G<T> {
//~^ ERROR: The requirement `T: std::marker::Sized` is added only by the Drop impl. [E0367]
//~^ ERROR `Drop` impl requires `T: std::marker::Sized`
fn drop(&mut self) {
if !self._ptr.is_null() {
}
Expand Down
16 changes: 5 additions & 11 deletions src/test/ui/issues/issue-17959.stderr
View file
@@ -1,16 +1,10 @@
error[E0367]: The requirement `T: std::marker::Sized` is added only by the Drop impl.
--> $DIR/issue-17959.rs:11:1
error[E0367]: `Drop` impl requires `T: std::marker::Sized` but the struct it is implemented for does not
--> $DIR/issue-17959.rs:11:6
|
LL | / impl<T> Drop for G<T> {
LL | |
LL | | fn drop(&mut self) {
LL | | if !self._ptr.is_null() {
LL | | }
LL | | }
LL | | }
| |_^
LL | impl<T> Drop for G<T> {
| ^
|
note: The same requirement must be part of the struct/enum definition
note: the implementor must specify the same requirement
--> $DIR/issue-17959.rs:7:1
|
LL | / struct G<T: ?Sized> {
Expand Down
4 changes: 2 additions & 2 deletions src/test/ui/issues/issue-38868.stderr
View file
@@ -1,4 +1,4 @@
error[E0366]: Implementations of Drop cannot be specialized
error[E0366]: `Drop` impls cannot be specialized
--> $DIR/issue-38868.rs:5:1
|
LL | / impl Drop for List<i32> {
Expand All @@ -8,7 +8,7 @@ LL | | }
LL | | }
| |_^
|
note: Use same sequence of generic type and region parameters that is on the struct/enum definition
note: use the same sequence of generic type, lifetime and const parameters as the struct definition
--> $DIR/issue-38868.rs:1:1
|
LL | / pub struct List<T> {
Expand Down
27 changes: 20 additions & 7 deletions src/test/ui/reject-specialized-drops-8142.rs
View file
@@ -1,5 +1,5 @@
// Issue 8142: Test that Drop impls cannot be specialized beyond the
// predicates attached to the struct/enum definition itself.
// predicates attached to the type definition itself.

trait Bound { fn foo(&self) { } }
struct K<'l1,'l2> { x: &'l1 i8, y: &'l2 u8 }
Expand All @@ -16,12 +16,16 @@ struct U;
struct V<Tva, Tvb> { x: *const Tva, y: *const Tvb }
struct W<'l1, 'l2> { x: &'l1 i8, y: &'l2 u8 }

enum Enum<T> { Variant(T) }
struct TupleStruct<T>(T);
union Union<T: Copy> { f: T }

impl<'al,'adds_bnd:'al> Drop for K<'al,'adds_bnd> { // REJECT
//~^ ERROR The requirement `'adds_bnd : 'al` is added only by the Drop impl.
//~^ ERROR `Drop` impl requires `'adds_bnd : 'al`
fn drop(&mut self) { } }

impl<'al,'adds_bnd> Drop for L<'al,'adds_bnd> where 'adds_bnd:'al { // REJECT
//~^ ERROR The requirement `'adds_bnd : 'al` is added only by the Drop impl.
//~^ ERROR `Drop` impl requires `'adds_bnd : 'al`
fn drop(&mut self) { } }

impl<'ml> Drop for M<'ml> { fn drop(&mut self) { } } // ACCEPT
Expand All @@ -34,13 +38,13 @@ impl Drop for N<'static> { fn drop(&mut self) { } } // RE
impl<COkNoBound> Drop for O<COkNoBound> { fn drop(&mut self) { } } // ACCEPT

impl Drop for P<i8> { fn drop(&mut self) { } } // REJECT
//~^ ERROR Implementations of Drop cannot be specialized
//~^ ERROR `Drop` impls cannot be specialized

impl<AddsBnd:Bound> Drop for Q<AddsBnd> { fn drop(&mut self) { } } // REJECT
//~^ ERROR The requirement `AddsBnd: Bound` is added only by the Drop impl.
//~^ ERROR `Drop` impl requires `AddsBnd: Bound`

impl<'rbnd,AddsRBnd:'rbnd> Drop for R<AddsRBnd> { fn drop(&mut self) { } } // REJECT
//~^ ERROR The requirement `AddsRBnd : 'rbnd` is added only by the Drop impl.
//~^ ERROR `Drop` impl requires `AddsRBnd : 'rbnd`

impl<Bs:Bound> Drop for S<Bs> { fn drop(&mut self) { } } // ACCEPT

Expand All @@ -49,9 +53,18 @@ impl<'t,Bt:'t> Drop for T<'t,Bt> { fn drop(&mut self) { } } // ACCEPT
impl Drop for U { fn drop(&mut self) { } } // ACCEPT

impl<One> Drop for V<One,One> { fn drop(&mut self) { } } // REJECT
//~^ ERROR Implementations of Drop cannot be specialized
//~^ ERROR `Drop` impls cannot be specialized

impl<'lw> Drop for W<'lw,'lw> { fn drop(&mut self) { } } // REJECT
//~^ ERROR cannot infer an appropriate lifetime for lifetime parameter `'lw`

impl<AddsBnd:Bound> Drop for Enum<AddsBnd> { fn drop(&mut self) { } } // REJECT
//~^ ERROR `Drop` impl requires `AddsBnd: Bound`

impl<AddsBnd:Bound> Drop for TupleStruct<AddsBnd> { fn drop(&mut self) { } } // REJECT
//~^ ERROR `Drop` impl requires `AddsBnd: Bound`

impl<AddsBnd:Copy + Bound> Drop for Union<AddsBnd> { fn drop(&mut self) { } } // REJECT
//~^ ERROR `Drop` impl requires `AddsBnd: Bound`

pub fn main() { }
96 changes: 64 additions & 32 deletions src/test/ui/reject-specialized-drops-8142.stderr
View file
@@ -1,33 +1,41 @@
error[E0367]: The requirement `'adds_bnd : 'al` is added only by the Drop impl.
--> $DIR/reject-specialized-drops-8142.rs:19:1
error[E0367]: `Drop` impl requires `AddsBnd: Bound` but the union it is implemented for does not
--> $DIR/reject-specialized-drops-8142.rs:67:21
|
LL | impl<AddsBnd:Copy + Bound> Drop for Union<AddsBnd> { fn drop(&mut self) { } } // REJECT
| ^^^^^
|
note: the implementor must specify the same requirement
--> $DIR/reject-specialized-drops-8142.rs:21:1
|
LL | union Union<T: Copy> { f: T }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0367]: `Drop` impl requires `'adds_bnd : 'al` but the struct it is implemented for does not
--> $DIR/reject-specialized-drops-8142.rs:23:20
|
LL | / impl<'al,'adds_bnd:'al> Drop for K<'al,'adds_bnd> { // REJECT
LL | |
LL | | fn drop(&mut self) { } }
| |____________________________^
LL | impl<'al,'adds_bnd:'al> Drop for K<'al,'adds_bnd> { // REJECT
| ^^^
|
note: The same requirement must be part of the struct/enum definition
note: the implementor must specify the same requirement
--> $DIR/reject-specialized-drops-8142.rs:5:1
|
LL | struct K<'l1,'l2> { x: &'l1 i8, y: &'l2 u8 }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0367]: The requirement `'adds_bnd : 'al` is added only by the Drop impl.
--> $DIR/reject-specialized-drops-8142.rs:23:1
error[E0367]: `Drop` impl requires `'adds_bnd : 'al` but the struct it is implemented for does not
--> $DIR/reject-specialized-drops-8142.rs:27:67
|
LL | / impl<'al,'adds_bnd> Drop for L<'al,'adds_bnd> where 'adds_bnd:'al { // REJECT
LL | |
LL | | fn drop(&mut self) { } }
| |____________________________^
LL | impl<'al,'adds_bnd> Drop for L<'al,'adds_bnd> where 'adds_bnd:'al { // REJECT
| ^^^
|
note: The same requirement must be part of the struct/enum definition
note: the implementor must specify the same requirement
--> $DIR/reject-specialized-drops-8142.rs:6:1
|
LL | struct L<'l1,'l2> { x: &'l1 i8, y: &'l2 u8 }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
--> $DIR/reject-specialized-drops-8142.rs:29:1
--> $DIR/reject-specialized-drops-8142.rs:33:1
|
LL | impl Drop for N<'static> { fn drop(&mut self) { } } // REJECT
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ lifetime mismatch
Expand All @@ -41,56 +49,56 @@ LL | struct N<'n> { x: &'n i8 }
| ^^
= note: ...does not necessarily outlive the static lifetime

error[E0366]: Implementations of Drop cannot be specialized
--> $DIR/reject-specialized-drops-8142.rs:36:1
error[E0366]: `Drop` impls cannot be specialized
--> $DIR/reject-specialized-drops-8142.rs:40:1
|
LL | impl Drop for P<i8> { fn drop(&mut self) { } } // REJECT
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: Use same sequence of generic type and region parameters that is on the struct/enum definition
note: use the same sequence of generic type, lifetime and const parameters as the struct definition
--> $DIR/reject-specialized-drops-8142.rs:10:1
|
LL | struct P<Tp> { x: *const Tp }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0367]: The requirement `AddsBnd: Bound` is added only by the Drop impl.
--> $DIR/reject-specialized-drops-8142.rs:39:1
error[E0367]: `Drop` impl requires `AddsBnd: Bound` but the struct it is implemented for does not
--> $DIR/reject-specialized-drops-8142.rs:43:14
|
LL | impl<AddsBnd:Bound> Drop for Q<AddsBnd> { fn drop(&mut self) { } } // REJECT
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^
|
note: The same requirement must be part of the struct/enum definition
note: the implementor must specify the same requirement
--> $DIR/reject-specialized-drops-8142.rs:11:1
|
LL | struct Q<Tq> { x: *const Tq }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0367]: The requirement `AddsRBnd : 'rbnd` is added only by the Drop impl.
--> $DIR/reject-specialized-drops-8142.rs:42:1
error[E0367]: `Drop` impl requires `AddsRBnd : 'rbnd` but the struct it is implemented for does not
--> $DIR/reject-specialized-drops-8142.rs:46:21
|
LL | impl<'rbnd,AddsRBnd:'rbnd> Drop for R<AddsRBnd> { fn drop(&mut self) { } } // REJECT
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^
|
note: The same requirement must be part of the struct/enum definition
note: the implementor must specify the same requirement
--> $DIR/reject-specialized-drops-8142.rs:12:1
|
LL | struct R<Tr> { x: *const Tr }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0366]: Implementations of Drop cannot be specialized
--> $DIR/reject-specialized-drops-8142.rs:51:1
error[E0366]: `Drop` impls cannot be specialized
--> $DIR/reject-specialized-drops-8142.rs:55:1
|
LL | impl<One> Drop for V<One,One> { fn drop(&mut self) { } } // REJECT
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: Use same sequence of generic type and region parameters that is on the struct/enum definition
note: use the same sequence of generic type, lifetime and const parameters as the struct definition
--> $DIR/reject-specialized-drops-8142.rs:16:1
|
LL | struct V<Tva, Tvb> { x: *const Tva, y: *const Tvb }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'lw` due to conflicting requirements
--> $DIR/reject-specialized-drops-8142.rs:54:1
--> $DIR/reject-specialized-drops-8142.rs:58:1
|
LL | impl<'lw> Drop for W<'lw,'lw> { fn drop(&mut self) { } } // REJECT
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -106,14 +114,38 @@ note: ...but the lifetime must also be valid for the lifetime `'l2` as defined o
LL | struct W<'l1, 'l2> { x: &'l1 i8, y: &'l2 u8 }
| ^^^
note: ...so that the types are compatible
--> $DIR/reject-specialized-drops-8142.rs:54:1
--> $DIR/reject-specialized-drops-8142.rs:58:1
|
LL | impl<'lw> Drop for W<'lw,'lw> { fn drop(&mut self) { } } // REJECT
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: expected `W<'l1, 'l2>`
found `W<'_, '_>`

error: aborting due to 8 previous errors
error[E0367]: `Drop` impl requires `AddsBnd: Bound` but the enum it is implemented for does not
--> $DIR/reject-specialized-drops-8142.rs:61:14
|
LL | impl<AddsBnd:Bound> Drop for Enum<AddsBnd> { fn drop(&mut self) { } } // REJECT
| ^^^^^
|
note: the implementor must specify the same requirement
--> $DIR/reject-specialized-drops-8142.rs:19:1
|
LL | enum Enum<T> { Variant(T) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0367]: `Drop` impl requires `AddsBnd: Bound` but the struct it is implemented for does not
--> $DIR/reject-specialized-drops-8142.rs:64:14
|
LL | impl<AddsBnd:Bound> Drop for TupleStruct<AddsBnd> { fn drop(&mut self) { } } // REJECT
| ^^^^^
|
note: the implementor must specify the same requirement
--> $DIR/reject-specialized-drops-8142.rs:20:1
|
LL | struct TupleStruct<T>(T);
| ^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 11 previous errors

Some errors have detailed explanations: E0308, E0366, E0367, E0495.
For more information about an error, try `rustc --explain E0308`.

0 comments on commit e589358

Please sign in to comment.