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rework ptr-to-ref conversion suggestion for method calls

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This commit is contained in:
Kalle Wachsmuth 2024-03-24 17:42:16 +01:00
parent 277e61854e
commit 3a2a3ae0b3
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GPG Key ID: 0B52AE391C674CE5
3 changed files with 110 additions and 15 deletions
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46
compiler/rustc_hir_typeck/src/method/suggest.rs
View File

@ -529,16 +529,44 @@ pub fn report_no_match_method_error(
Applicability::MachineApplicable,
);
}
if let ty::RawPtr(_, _) = &rcvr_ty.kind() {
err.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",
);
err.note(
"using `<*const T>::as_ref()` on a pointer which is unaligned or points \
to invalid or uninitialized memory is undefined behavior",
// on pointers, check if the method would exist on a reference
if let SelfSource::MethodCall(rcvr_expr) = source
&& let ty::RawPtr(ty, ptr_mutbl) = *rcvr_ty.kind()
&& let Ok(pick) = self.lookup_probe_for_diagnostic(
item_name,
Ty::new_ref(tcx, ty::Region::new_error_misc(tcx), ty, ptr_mutbl),
self.tcx.hir().expect_expr(self.tcx.parent_hir_id(rcvr_expr.hir_id)),
ProbeScope::TraitsInScope,
None,
)
&& let ty::Ref(_, _, sugg_mutbl) = *pick.self_ty.kind()
&& (sugg_mutbl.is_not() || ptr_mutbl.is_mut())
{
let (method, method_anchor) = match sugg_mutbl {
Mutability::Not => {
let method_anchor = match ptr_mutbl {
Mutability::Not => "as_ref",
Mutability::Mut => "as_ref-1",
};
("as_ref", method_anchor)
}
Mutability::Mut => ("as_mut", "as_mut"),
};
err.span_note(
tcx.def_span(pick.item.def_id),
format!("the method `{item_name}` exists on the type `{ty}`", ty = pick.self_ty),
);
let mut_str = ptr_mutbl.ptr_str();
err.note(format!(
"you might want to use the unsafe method `<*{mut_str} T>::{method}` to get \
an optional reference to the value behind the pointer"
));
err.note(format!(
"read the documentation for `<*{mut_str} T>::{method}` and ensure you satisfy its \
safety preconditions before calling it to avoid undefined behavior: \
https://doc.rust-lang.org/std/primitive.pointer.html#method.{method_anchor}"
));
}
let mut ty_span = match rcvr_ty.kind() {

16
tests/ui/methods/suggest-convert-ptr-to-ref.rs
View File

@ -1,5 +1,17 @@
fn main() {
let x = 8u8;
let mut x = 8u8;
let z: *const u8 = &x;
println!("{}", z.to_string()); //~ ERROR E0599
// issue #21596
println!("{}", z.to_string()); //~ ERROR E0599
let t: *mut u8 = &mut x;
println!("{}", t.to_string()); //~ ERROR E0599
t.make_ascii_lowercase(); //~ ERROR E0599
// suggest `as_mut` simply because the name is similar
let _ = t.as_mut_ref(); //~ ERROR E0599
let _ = t.as_ref_mut(); //~ ERROR E0599
// no ptr-to-ref suggestion
z.make_ascii_lowercase(); //~ ERROR E0599
}

63
tests/ui/methods/suggest-convert-ptr-to-ref.stderr
View File

@ -1,15 +1,70 @@
error[E0599]: `*const u8` doesn't implement `std::fmt::Display`
--> $DIR/issue-21596.rs:4:22
--> $DIR/suggest-convert-ptr-to-ref.rs:5:22
|
LL | println!("{}", z.to_string());
| ^^^^^^^^^ `*const u8` cannot be formatted with the default formatter
|
= 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
= note: using `<*const T>::as_ref()` on a pointer which is unaligned or points to invalid or uninitialized memory is undefined behavior
note: the method `to_string` exists on the type `&u8`
--> $SRC_DIR/alloc/src/string.rs:LL:COL
= note: you might want to use the unsafe method `<*const T>::as_ref` to get an optional reference to the value behind the pointer
= note: read the documentation for `<*const T>::as_ref` and ensure you satisfy its safety preconditions before calling it to avoid undefined behavior: https://doc.rust-lang.org/std/primitive.pointer.html#method.as_ref
= note: the following trait bounds were not satisfied:
`*const u8: std::fmt::Display`
which is required by `*const u8: ToString`
error: aborting due to 1 previous error
error[E0599]: `*mut u8` doesn't implement `std::fmt::Display`
--> $DIR/suggest-convert-ptr-to-ref.rs:8:22
|
LL | println!("{}", t.to_string());
| ^^^^^^^^^ `*mut u8` cannot be formatted with the default formatter
|
note: the method `to_string` exists on the type `&&mut u8`
--> $SRC_DIR/alloc/src/string.rs:LL:COL
= note: you might want to use the unsafe method `<*mut T>::as_ref` to get an optional reference to the value behind the pointer
= note: read the documentation for `<*mut T>::as_ref` and ensure you satisfy its safety preconditions before calling it to avoid undefined behavior: https://doc.rust-lang.org/std/primitive.pointer.html#method.as_ref-1
= note: the following trait bounds were not satisfied:
`*mut u8: std::fmt::Display`
which is required by `*mut u8: ToString`
error[E0599]: no method named `make_ascii_lowercase` found for raw pointer `*mut u8` in the current scope
--> $DIR/suggest-convert-ptr-to-ref.rs:9:7
|
LL | t.make_ascii_lowercase();
| ^^^^^^^^^^^^^^^^^^^^ method not found in `*mut u8`
|
note: the method `make_ascii_lowercase` exists on the type `&mut u8`
--> $SRC_DIR/core/src/num/mod.rs:LL:COL
= note: you might want to use the unsafe method `<*mut T>::as_mut` to get an optional reference to the value behind the pointer
= note: read the documentation for `<*mut T>::as_mut` and ensure you satisfy its safety preconditions before calling it to avoid undefined behavior: https://doc.rust-lang.org/std/primitive.pointer.html#method.as_mut
error[E0599]: no method named `as_mut_ref` found for raw pointer `*mut u8` in the current scope
--> $DIR/suggest-convert-ptr-to-ref.rs:12:15
|
LL | let _ = t.as_mut_ref();
| ^^^^^^^^^^
|
help: there is a method `as_mut` with a similar name
|
LL | let _ = t.as_mut();
| ~~~~~~
error[E0599]: no method named `as_ref_mut` found for raw pointer `*mut u8` in the current scope
--> $DIR/suggest-convert-ptr-to-ref.rs:13:15
|
LL | let _ = t.as_ref_mut();
| ^^^^^^^^^^
|
help: there is a method `as_mut` with a similar name
|
LL | let _ = t.as_mut();
| ~~~~~~
error[E0599]: no method named `make_ascii_lowercase` found for raw pointer `*const u8` in the current scope
--> $DIR/suggest-convert-ptr-to-ref.rs:16:7
|
LL | z.make_ascii_lowercase();
| ^^^^^^^^^^^^^^^^^^^^ method not found in `*const u8`
error: aborting due to 6 previous errors
For more information about this error, try `rustc --explain E0599`.