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Commit b5e7a1c

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rework ptr-to-ref conversion suggestion for method calls
1 parent 9250906 commit b5e7a1c

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3 files changed

+103
-15
lines changed

3 files changed

+103
-15
lines changed

‎compiler/rustc_hir_typeck/src/method/suggest.rs‎

Lines changed: 33 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -530,16 +530,40 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
530530
Applicability::MachineApplicable,
531531
);
532532
}
533-
if let ty::RawPtr(_, _) = &rcvr_ty.kind() {
534-
err.note(
535-
"try using `<*const T>::as_ref()` to get a reference to the \
536-
type behind the pointer: https://doc.rust-lang.org/std/\
537-
primitive.pointer.html#method.as_ref",
538-
);
539-
err.note(
540-
"using `<*const T>::as_ref()` on a pointer which is unaligned or points \
541-
to invalid or uninitialized memory is undefined behavior",
533+
534+
// on pointers, check if the method would exist on a reference
535+
if let SelfSource::MethodCall(rcvr_expr) = source
536+
&& let ty::RawPtr(ty, ptr_mutbl) = *rcvr_ty.kind()
537+
&& let Ok(pick) = self.lookup_probe_for_diagnostic(
538+
item_name,
539+
Ty::new_ref(tcx, ty::Region::new_error_misc(tcx), ty, ptr_mutbl),
540+
self.tcx.hir().expect_expr(self.tcx.parent_hir_id(rcvr_expr.hir_id)),
541+
ProbeScope::TraitsInScope,
542+
None,
543+
)
544+
&& let ty::Ref(_, _, sugg_mutbl) = *pick.self_ty.kind()
545+
&& (sugg_mutbl.is_not() || ptr_mutbl.is_mut())
546+
{
547+
let (method, method_anchor) = match sugg_mutbl {
548+
Mutability::Not => {
549+
let method_anchor = match ptr_mutbl {
550+
Mutability::Not => "as_ref",
551+
Mutability::Mut => "as_ref-1",
552+
};
553+
("as_ref", method_anchor)
554+
}
555+
Mutability::Mut => ("as_mut", "as_mut"),
556+
};
557+
err.span_note(
558+
tcx.def_span(pick.item.def_id),
559+
format!("the method `{item_name}` exists on the type `{ty}`", ty = pick.self_ty),
542560
);
561+
err.note(format!(
562+
"try using the unsafe method `<*{mut_str} T>::{method}` to get \
563+
an optional reference to the value behind the pointer: \
564+
https://doc.rust-lang.org/std/primitive.pointer.html#method.{method_anchor}",
565+
mut_str = ptr_mutbl.ptr_str()
566+
));
543567
}
544568

545569
let mut ty_span = match rcvr_ty.kind() {
Lines changed: 14 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,17 @@
11
fn main() {
2-
let x = 8u8;
2+
let mutx = 8u8;
33
let z: *const u8 = &x;
4-
println!("{}", z.to_string()); //~ ERROR E0599
4+
// issue #21596
5+
println!("{}", z.to_string()); //~ ERROR E0599
6+
7+
let t: *mut u8 = &mut x;
8+
println!("{}", t.to_string()); //~ ERROR E0599
9+
t.make_ascii_lowercase(); //~ ERROR E0599
10+
11+
// suggest `as_mut` simply because the name is similar
12+
let _ = t.as_mut_ref(); //~ ERROR E0599
13+
let _ = t.as_ref_mut(); //~ ERROR E0599
14+
15+
// no ptr-to-ref suggestion
16+
z.make_ascii_lowercase(); //~ ERROR E0599
517
}
Lines changed: 56 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,67 @@
11
error[E0599]: `*const u8` doesn't implement `std::fmt::Display`
2-
--> $DIR/issue-21596.rs:4:22
2+
--> $DIR/suggest-convert-ptr-to-ref.rs:5:22
33
|
44
LL | println!("{}", z.to_string());
55
| ^^^^^^^^^ `*const u8` cannot be formatted with the default formatter
66
|
7-
= note: try using `<*const T>::as_ref()` to get a reference to the type behind the pointer: https://doc.rust-lang.org/std/primitive.pointer.html#method.as_ref
8-
= note: using `<*const T>::as_ref()` on a pointer which is unaligned or points to invalid or uninitialized memory is undefined behavior
7+
note: the method `to_string` exists on the type `&u8`
8+
--> $SRC_DIR/alloc/src/string.rs:LL:COL
9+
= note: try using the unsafe method `<*const T>::as_ref` to get an optional reference to the value behind the pointer: https://doc.rust-lang.org/std/primitive.pointer.html#method.as_ref
910
= note: the following trait bounds were not satisfied:
1011
`*const u8: std::fmt::Display`
1112
which is required by `*const u8: ToString`
1213

13-
error: aborting due to 1 previous error
14+
error[E0599]: `*mut u8` doesn't implement `std::fmt::Display`
15+
--> $DIR/suggest-convert-ptr-to-ref.rs:8:22
16+
|
17+
LL | println!("{}", t.to_string());
18+
| ^^^^^^^^^ `*mut u8` cannot be formatted with the default formatter
19+
|
20+
note: the method `to_string` exists on the type `&&mut u8`
21+
--> $SRC_DIR/alloc/src/string.rs:LL:COL
22+
= note: try using the unsafe method `<*mut T>::as_ref` to get an optional reference to the value behind the pointer: https://doc.rust-lang.org/std/primitive.pointer.html#method.as_ref-1
23+
= note: the following trait bounds were not satisfied:
24+
`*mut u8: std::fmt::Display`
25+
which is required by `*mut u8: ToString`
26+
27+
error[E0599]: no method named `make_ascii_lowercase` found for raw pointer `*mut u8` in the current scope
28+
--> $DIR/suggest-convert-ptr-to-ref.rs:9:7
29+
|
30+
LL | t.make_ascii_lowercase();
31+
| ^^^^^^^^^^^^^^^^^^^^ method not found in `*mut u8`
32+
|
33+
note: the method `make_ascii_lowercase` exists on the type `&mut u8`
34+
--> $SRC_DIR/core/src/num/mod.rs:LL:COL
35+
= note: try using the unsafe method `<*mut T>::as_mut` to get an optional reference to the value behind the pointer: https://doc.rust-lang.org/std/primitive.pointer.html#method.as_mut
36+
37+
error[E0599]: no method named `as_mut_ref` found for raw pointer `*mut u8` in the current scope
38+
--> $DIR/suggest-convert-ptr-to-ref.rs:12:15
39+
|
40+
LL | let _ = t.as_mut_ref();
41+
| ^^^^^^^^^^
42+
|
43+
help: there is a method `as_mut` with a similar name
44+
|
45+
LL | let _ = t.as_mut();
46+
| ~~~~~~
47+
48+
error[E0599]: no method named `as_ref_mut` found for raw pointer `*mut u8` in the current scope
49+
--> $DIR/suggest-convert-ptr-to-ref.rs:13:15
50+
|
51+
LL | let _ = t.as_ref_mut();
52+
| ^^^^^^^^^^
53+
|
54+
help: there is a method `as_mut` with a similar name
55+
|
56+
LL | let _ = t.as_mut();
57+
| ~~~~~~
58+
59+
error[E0599]: no method named `make_ascii_lowercase` found for raw pointer `*const u8` in the current scope
60+
--> $DIR/suggest-convert-ptr-to-ref.rs:16:7
61+
|
62+
LL | z.make_ascii_lowercase();
63+
| ^^^^^^^^^^^^^^^^^^^^ method not found in `*const u8`
64+
65+
error: aborting due to 6 previous errors
1466

1567
For more information about this error, try `rustc --explain E0599`.

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