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Account for trait/impl difference when suggesting changing argument from ref to mut ref

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Do not ICE when encountering a lifetime error involving an argument with
an immutable reference of a method that differs from the trait definition.

Fix #123414.
This commit is contained in:
Esteban Küber 2024-04-05 23:27:58 +00:00
parent 76cf07d5df
commit 731c0e59a4
7 changed files with 158 additions and 43 deletions
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89
compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
View File

@ -21,7 +21,7 @@
use crate::diagnostics::BorrowedContentSource;
use crate::util::FindAssignments;
use crate::MirBorrowckCtxt;
use crate::{session_diagnostics, MirBorrowckCtxt};
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub(crate) enum AccessKind {
@ -234,7 +234,7 @@ pub(crate) fn report_mutability_error(
Some(mir::BorrowKind::Mut { kind: mir::MutBorrowKind::Default }),
|_kind, var_span| {
let place = self.describe_any_place(access_place.as_ref());
crate::session_diagnostics::CaptureVarCause::MutableBorrowUsePlaceClosure {
session_diagnostics::CaptureVarCause::MutableBorrowUsePlaceClosure {
place,
var_span,
}
@ -667,19 +667,26 @@ fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
/// User cannot make signature of a trait mutable without changing the
/// trait. So we find if this error belongs to a trait and if so we move
/// suggestion to the trait or disable it if it is out of scope of this crate
fn is_error_in_trait(&self, local: Local) -> (bool, Option<Span>) {
///
/// The returned values are:
/// - is the current item an assoc `fn` of an impl that corresponds to a trait def? if so, we
/// have to suggest changing both the impl `fn` arg and the trait `fn` arg
/// - is the trait from the local crate? If not, we can't suggest changing signatures
/// - `Span` of the argument in the trait definition
fn is_error_in_trait(&self, local: Local) -> (bool, bool, Option<Span>) {
if self.body.local_kind(local) != LocalKind::Arg {
return (false, None);
return (false, false, None);
}
let my_def = self.body.source.def_id();
let my_hir = self.infcx.tcx.local_def_id_to_hir_id(my_def.as_local().unwrap());
let Some(td) =
self.infcx.tcx.impl_of_method(my_def).and_then(|x| self.infcx.tcx.trait_id_of_impl(x))
else {
return (false, None);
return (false, false, None);
};
(
true,
td.is_local(),
td.as_local().and_then(|tld| match self.infcx.tcx.hir_node_by_def_id(tld) {
Node::Item(hir::Item { kind: hir::ItemKind::Trait(_, _, _, _, items), .. }) => {
let mut f_in_trait_opt = None;
@ -695,19 +702,16 @@ fn is_error_in_trait(&self, local: Local) -> (bool, Option<Span>) {
break;
}
f_in_trait_opt.and_then(|f_in_trait| {
match self.infcx.tcx.hir_node(f_in_trait) {
Node::TraitItem(hir::TraitItem {
kind:
hir::TraitItemKind::Fn(
hir::FnSig { decl: hir::FnDecl { inputs, .. }, .. },
_,
),
..
}) => {
let hir::Ty { span, .. } = *inputs.get(local.index() - 1)?;
Some(span)
}
_ => None,
if let Node::TraitItem(ti) = self.infcx.tcx.hir_node(f_in_trait)
&& let hir::TraitItemKind::Fn(sig, _) = ti.kind
&& let Some(ty) = sig.decl.inputs.get(local.index() - 1)
&& let hir::TyKind::Ref(_, mut_ty) = ty.kind
&& let hir::Mutability::Not = mut_ty.mutbl
&& sig.decl.implicit_self.has_implicit_self()
{
Some(ty.span)
} else {
None
}
})
}
@ -1061,20 +1065,24 @@ fn suggest_make_local_mut(&self, err: &mut Diag<'_>, local: Local, name: Symbol)
let (pointer_sigil, pointer_desc) =
if local_decl.ty.is_ref() { ("&", "reference") } else { ("*const", "pointer") };
let (is_trait_sig, local_trait) = self.is_error_in_trait(local);
if is_trait_sig && local_trait.is_none() {
let (is_trait_sig, is_local, local_trait) = self.is_error_in_trait(local);
if is_trait_sig && !is_local {
// Do not suggest to change the signature when the trait comes from another crate.
err.span_label(
local_decl.source_info.span,
format!("this is an immutable {pointer_desc}"),
);
return;
}
let decl_span = match local_trait {
Some(span) => span,
None => local_decl.source_info.span,
};
let decl_span = local_decl.source_info.span;
let label = match *local_decl.local_info() {
LocalInfo::User(mir::BindingForm::ImplicitSelf(_)) => {
let suggestion = suggest_ampmut_self(self.infcx.tcx, decl_span);
Some((true, decl_span, suggestion))
let additional =
local_trait.map(|span| (span, suggest_ampmut_self(self.infcx.tcx, span)));
Some((true, decl_span, suggestion, additional))
}
LocalInfo::User(mir::BindingForm::Var(mir::VarBindingForm {
@ -1113,7 +1121,7 @@ fn suggest_make_local_mut(&self, err: &mut Diag<'_>, local: Local, name: Symbol)
// don't create labels for compiler-generated spans
Some(_) => None,
None => {
let label = if name != kw::SelfLower {
let (has_sugg, decl_span, sugg) = if name != kw::SelfLower {
suggest_ampmut(
self.infcx.tcx,
local_decl.ty,
@ -1140,7 +1148,7 @@ fn suggest_make_local_mut(&self, err: &mut Diag<'_>, local: Local, name: Symbol)
),
}
};
Some(label)
Some((has_sugg, decl_span, sugg, None))
}
}
}
@ -1151,22 +1159,33 @@ fn suggest_make_local_mut(&self, err: &mut Diag<'_>, local: Local, name: Symbol)
})) => {
let pattern_span: Span = local_decl.source_info.span;
suggest_ref_mut(self.infcx.tcx, pattern_span)
.map(|span| (true, span, "mut ".to_owned()))
.map(|span| (true, span, "mut ".to_owned(), None))
}
_ => unreachable!(),
};
match label {
Some((true, err_help_span, suggested_code)) => {
err.span_suggestion_verbose(
err_help_span,
format!("consider changing this to be a mutable {pointer_desc}"),
suggested_code,
Some((true, err_help_span, suggested_code, additional)) => {
let mut sugg = vec![(err_help_span, suggested_code)];
if let Some(s) = additional {
sugg.push(s);
}
err.multipart_suggestion_verbose(
format!(
"consider changing this to be a mutable {pointer_desc}{}",
if is_trait_sig {
" in the `impl` method and the `trait` definition"
} else {
""
}
),
sugg,
Applicability::MachineApplicable,
);
}
Some((false, err_label_span, message)) => {
Some((false, err_label_span, message, _)) => {
let def_id = self.body.source.def_id();
let hir_id = if let Some(local_def_id) = def_id.as_local()
&& let Some(body_id) = self.infcx.tcx.hir().maybe_body_owned_by(local_def_id)

5
tests/ui/borrowck/argument_number_mismatch_ice.stderr
View File

@ -12,6 +12,11 @@ error[E0594]: cannot assign to `*input`, which is behind a `&` reference
|
LL | *input = self.0;
| ^^^^^^^^^^^^^^^ `input` is a `&` reference, so the data it refers to cannot be written
|
help: consider changing this to be a mutable reference in the `impl` method and the `trait` definition
|
LL | fn example(&self, input: &mut i32) {
| +++
error: aborting due to 2 previous errors

25
tests/ui/borrowck/trait-impl-argument-difference-ice.rs Normal file
View File

@ -0,0 +1,25 @@
// Issue https://github.com/rust-lang/rust/issues/123414
trait MemoryUnit {
extern "C" fn read_word(&mut self) -> u8;
extern "C" fn read_dword(Self::Assoc<'_>) -> u16;
//~^ WARNING anonymous parameters are deprecated and will be removed in the next edition
//~| WARNING this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2018!
//~| ERROR associated type `Assoc` not found for `Self`
}
struct ROM {}
impl MemoryUnit for ROM {
//~^ ERROR not all trait items implemented, missing: `read_word`
extern "C" fn read_dword(&'_ self) -> u16 {
//~^ ERROR method `read_dword` has a `&self` declaration in the impl, but not in the trait
let a16 = self.read_word() as u16;
//~^ ERROR cannot borrow `*self` as mutable, as it is behind a `&` reference
let b16 = self.read_word() as u16;
//~^ ERROR cannot borrow `*self` as mutable, as it is behind a `&` reference
(b16 << 8) | a16
}
}
pub fn main() {}

60
tests/ui/borrowck/trait-impl-argument-difference-ice.stderr Normal file
View File

@ -0,0 +1,60 @@
warning: anonymous parameters are deprecated and will be removed in the next edition
--> $DIR/trait-impl-argument-difference-ice.rs:4:30
|
LL | extern "C" fn read_dword(Self::Assoc<'_>) -> u16;
| ^^^^^^^^^^^^^^^ help: try naming the parameter or explicitly ignoring it: `_: Self::Assoc<'_>`
|
= warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2018!
= note: for more information, see issue #41686 <https://github.com/rust-lang/rust/issues/41686>
= note: `#[warn(anonymous_parameters)]` on by default
error[E0220]: associated type `Assoc` not found for `Self`
--> $DIR/trait-impl-argument-difference-ice.rs:4:36
|
LL | extern "C" fn read_dword(Self::Assoc<'_>) -> u16;
| ^^^^^ associated type `Assoc` not found
error[E0185]: method `read_dword` has a `&self` declaration in the impl, but not in the trait
--> $DIR/trait-impl-argument-difference-ice.rs:14:5
|
LL | extern "C" fn read_dword(Self::Assoc<'_>) -> u16;
| ------------------------------------------------- trait method declared without `&self`
...
LL | extern "C" fn read_dword(&'_ self) -> u16 {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `&self` used in impl
error[E0046]: not all trait items implemented, missing: `read_word`
--> $DIR/trait-impl-argument-difference-ice.rs:12:1
|
LL | extern "C" fn read_word(&mut self) -> u8;
| ----------------------------------------- `read_word` from trait
...
LL | impl MemoryUnit for ROM {
| ^^^^^^^^^^^^^^^^^^^^^^^ missing `read_word` in implementation
error[E0596]: cannot borrow `*self` as mutable, as it is behind a `&` reference
--> $DIR/trait-impl-argument-difference-ice.rs:16:19
|
LL | let a16 = self.read_word() as u16;
| ^^^^ `self` is a `&` reference, so the data it refers to cannot be borrowed as mutable
|
help: consider changing this to be a mutable reference in the `impl` method and the `trait` definition
|
LL | extern "C" fn read_dword(&'_ mut self) -> u16 {
| ~~~~~~~~~~~~
error[E0596]: cannot borrow `*self` as mutable, as it is behind a `&` reference
--> $DIR/trait-impl-argument-difference-ice.rs:18:19
|
LL | let b16 = self.read_word() as u16;
| ^^^^ `self` is a `&` reference, so the data it refers to cannot be borrowed as mutable
|
help: consider changing this to be a mutable reference in the `impl` method and the `trait` definition
|
LL | extern "C" fn read_dword(&'_ mut self) -> u16 {
| ~~~~~~~~~~~~
error: aborting due to 5 previous errors; 1 warning emitted
Some errors have detailed explanations: E0046, E0185, E0220, E0596.
For more information about an error, try `rustc --explain E0046`.

2
tests/ui/suggestions/issue-68049-1.stderr
View File

@ -1,6 +1,8 @@
error[E0594]: cannot assign to `self.0`, which is behind a `&` reference
--> $DIR/issue-68049-1.rs:7:9
|
LL | unsafe fn alloc(&self, _layout: Layout) -> *mut u8 {
| ----- this is an immutable reference
LL | self.0 += 1;
| ^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be written

6
tests/ui/suggestions/issue-68049-2.rs
View File

@ -1,11 +1,11 @@
trait Hello {
fn example(&self, input: &i32); // should suggest here
fn example(&self, input: &i32);
}
struct Test1(i32);
impl Hello for Test1 {
fn example(&self, input: &i32) { // should not suggest here
fn example(&self, input: &i32) {
*input = self.0; //~ ERROR cannot assign
}
}
@ -13,7 +13,7 @@ fn example(&self, input: &i32) { // should not suggest here
struct Test2(i32);
impl Hello for Test2 {
fn example(&self, input: &i32) { // should not suggest here
fn example(&self, input: &i32) {
self.0 += *input; //~ ERROR cannot assign
}
}

14
tests/ui/suggestions/issue-68049-2.stderr
View File

@ -4,9 +4,9 @@ error[E0594]: cannot assign to `*input`, which is behind a `&` reference
LL | *input = self.0;
| ^^^^^^^^^^^^^^^ `input` is a `&` reference, so the data it refers to cannot be written
|
help: consider changing this to be a mutable reference
help: consider changing this to be a mutable reference in the `impl` method and the `trait` definition
|
LL | fn example(&self, input: &mut i32) { // should not suggest here
LL | fn example(&self, input: &mut i32) {
| +++
error[E0594]: cannot assign to `self.0`, which is behind a `&` reference
@ -15,10 +15,14 @@ error[E0594]: cannot assign to `self.0`, which is behind a `&` reference
LL | self.0 += *input;
| ^^^^^^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be written
|
help: consider changing this to be a mutable reference
help: consider changing this to be a mutable reference in the `impl` method and the `trait` definition
|
LL ~ fn example(&mut self, input: &i32);
LL | }
...
LL | impl Hello for Test2 {
LL ~ fn example(&mut self, input: &i32) {
|
LL | fn example(&mut self, input: &i32); // should suggest here
| ~~~~~~~~~
error: aborting due to 2 previous errors