Suggest deref when coercing ty::Ref
to ty::RawPtr
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a9340b1f69
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@ -74,7 +74,7 @@ use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode};
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use smallvec::{smallvec, SmallVec};
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use std::ops::Deref;
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struct Coerce<'a, 'tcx> {
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pub struct Coerce<'a, 'tcx> {
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fcx: &'a FnCtxt<'a, 'tcx>,
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cause: ObligationCause<'tcx>,
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use_lub: bool,
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@ -124,7 +124,7 @@ fn success<'tcx>(
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}
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impl<'f, 'tcx> Coerce<'f, 'tcx> {
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fn new(
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pub fn new(
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fcx: &'f FnCtxt<'f, 'tcx>,
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cause: ObligationCause<'tcx>,
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allow_two_phase: AllowTwoPhase,
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@ -132,7 +132,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
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Coerce { fcx, cause, allow_two_phase, use_lub: false }
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}
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fn unify(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> InferResult<'tcx, Ty<'tcx>> {
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pub fn unify(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> InferResult<'tcx, Ty<'tcx>> {
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self.commit_if_ok(|_| {
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if self.use_lub {
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self.at(&self.cause, self.fcx.param_env).lub(b, a)
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@ -1,3 +1,4 @@
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use crate::check::coercion::Coerce;
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use crate::check::FnCtxt;
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use rustc_infer::infer::InferOk;
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use rustc_trait_selection::infer::InferCtxtExt as _;
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@ -8,8 +9,9 @@ use rustc_ast::util::parser::PREC_POSTFIX;
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use rustc_errors::{Applicability, DiagnosticBuilder};
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use rustc_hir as hir;
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use rustc_hir::{is_range_literal, Node};
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use rustc_middle::traits::ObligationCauseCode;
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use rustc_middle::ty::adjustment::AllowTwoPhase;
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use rustc_middle::ty::{self, AssocItem, Ty};
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use rustc_middle::ty::{self, AssocItem, Ty, TypeAndMut};
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use rustc_span::symbol::sym;
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use rustc_span::Span;
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@ -539,6 +541,40 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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return Some((sp, "consider removing the borrow", code));
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}
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}
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(
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_,
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&ty::RawPtr(TypeAndMut { ty: _, mutbl: hir::Mutability::Not }),
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&ty::Ref(_, _, hir::Mutability::Not),
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) => {
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let cause = self.cause(rustc_span::DUMMY_SP, ObligationCauseCode::ExprAssignable);
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// We don't ever need two-phase here since we throw out the result of the coercion
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let coerce = Coerce::new(self, cause, AllowTwoPhase::No);
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if let Some(steps) =
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coerce.autoderef(sp, checked_ty).skip(1).find_map(|(referent_ty, steps)| {
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coerce
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.unify(
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coerce.tcx.mk_ptr(ty::TypeAndMut {
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mutbl: hir::Mutability::Not,
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ty: referent_ty,
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}),
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expected,
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)
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.ok()
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.map(|_| steps)
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})
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{
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// The pointer type implements `Copy` trait so the suggestion is always valid.
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if let Ok(code) = sm.span_to_snippet(sp) {
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if code.starts_with('&') {
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let derefs = "*".repeat(steps - 1);
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let message = "consider dereferencing the reference";
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let suggestion = format!("&{}{}", derefs, code[1..].to_string());
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return Some((sp, message, suggestion));
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}
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}
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}
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}
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_ if sp == expr.span && !is_macro => {
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// Check for `Deref` implementations by constructing a predicate to
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// prove: `<T as Deref>::Output == U`
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17
src/test/ui/issues/issue-32122-1.fixed
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17
src/test/ui/issues/issue-32122-1.fixed
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@ -0,0 +1,17 @@
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// run-rustfix
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use std::ops::Deref;
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struct Foo(u8);
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impl Deref for Foo {
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type Target = u8;
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fn deref(&self) -> &Self::Target {
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&self.0
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}
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}
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fn main() {
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let a = Foo(0);
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// Should suggest `&*` when coercing &ty to *const ty
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let _: *const u8 = &*a; //~ ERROR mismatched types
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}
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17
src/test/ui/issues/issue-32122-1.rs
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17
src/test/ui/issues/issue-32122-1.rs
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@ -0,0 +1,17 @@
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// run-rustfix
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use std::ops::Deref;
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struct Foo(u8);
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impl Deref for Foo {
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type Target = u8;
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fn deref(&self) -> &Self::Target {
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&self.0
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}
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}
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fn main() {
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let a = Foo(0);
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// Should suggest `&*` when coercing &ty to *const ty
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let _: *const u8 = &a; //~ ERROR mismatched types
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}
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16
src/test/ui/issues/issue-32122-1.stderr
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16
src/test/ui/issues/issue-32122-1.stderr
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@ -0,0 +1,16 @@
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error[E0308]: mismatched types
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--> $DIR/issue-32122-1.rs:16:24
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LL | let _: *const u8 = &a;
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| --------- ^^
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| | |
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| | expected `u8`, found struct `Foo`
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| | help: consider dereferencing the reference: `&*a`
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| expected due to this
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= note: expected raw pointer `*const u8`
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found reference `&Foo`
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error: aborting due to previous error
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For more information about this error, try `rustc --explain E0308`.
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28
src/test/ui/issues/issue-32122-2.fixed
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28
src/test/ui/issues/issue-32122-2.fixed
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@ -0,0 +1,28 @@
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// run-rustfix
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use std::ops::Deref;
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struct Bar(u8);
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struct Foo(Bar);
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struct Emm(Foo);
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impl Deref for Bar{
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type Target = u8;
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fn deref(&self) -> &Self::Target {
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&self.0
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}
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}
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impl Deref for Foo {
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type Target = Bar;
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fn deref(&self) -> &Self::Target {
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&self.0
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}
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}
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impl Deref for Emm {
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type Target = Foo;
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fn deref(&self) -> &Self::Target {
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&self.0
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}
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}
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fn main() {
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let a = Emm(Foo(Bar(0)));
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// Should suggest `&***` even when deref is pretty deep
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let _: *const u8 = &***a; //~ ERROR mismatched types
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}
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28
src/test/ui/issues/issue-32122-2.rs
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28
src/test/ui/issues/issue-32122-2.rs
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@ -0,0 +1,28 @@
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// run-rustfix
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use std::ops::Deref;
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struct Bar(u8);
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struct Foo(Bar);
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struct Emm(Foo);
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impl Deref for Bar{
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type Target = u8;
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fn deref(&self) -> &Self::Target {
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&self.0
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}
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}
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impl Deref for Foo {
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type Target = Bar;
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fn deref(&self) -> &Self::Target {
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&self.0
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}
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}
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impl Deref for Emm {
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type Target = Foo;
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fn deref(&self) -> &Self::Target {
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&self.0
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}
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}
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fn main() {
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let a = Emm(Foo(Bar(0)));
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// Should suggest `&***` even when deref is pretty deep
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let _: *const u8 = &a; //~ ERROR mismatched types
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}
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16
src/test/ui/issues/issue-32122-2.stderr
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16
src/test/ui/issues/issue-32122-2.stderr
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error[E0308]: mismatched types
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--> $DIR/issue-32122-2.rs:27:24
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LL | let _: *const u8 = &a;
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| --------- ^^
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| | |
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| | expected `u8`, found struct `Emm`
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| | help: consider dereferencing the reference: `&***a`
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| expected due to this
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= note: expected raw pointer `*const u8`
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found reference `&Emm`
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error: aborting due to previous error
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For more information about this error, try `rustc --explain E0308`.
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