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Helpful suggestions for incorrect address-of mutability (2) #162106

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24 changes: 24 additions & 0 deletions compiler/rustc_hir_typeck/src/diagnostics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -679,6 +679,30 @@ pub(crate) struct SuggestPtrNullMut {
pub span: Span,
}

#[derive(Subdiagnostic)]
#[suggestion(
"consider using `&mut` instead",
applicability = "maybe-incorrect",
style = "verbose",
code = "&mut "
)]
pub(crate) struct SuggestRefMut {
#[primary_span]
pub span: Span,
}

#[derive(Subdiagnostic)]
#[suggestion(
"consider using `&raw mut` instead",
applicability = "maybe-incorrect",
style = "verbose",
code = "&raw mut "
)]
pub(crate) struct SuggestRawMut {
#[primary_span]
pub span: Span,
}

#[derive(Diagnostic)]
#[diag(
"trivial {$numeric ->
Expand Down
61 changes: 50 additions & 11 deletions compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,7 @@ use crate::Expectation::*;
use crate::TupleArgumentsFlag::*;
use crate::callee::SplatLoweringInfo;
use crate::coercion::CoerceMany;
use crate::diagnostics::{ExprParenthesesNeeded, SuggestPtrNullMut};
use crate::diagnostics::{ExprParenthesesNeeded, SuggestPtrNullMut, SuggestRawMut, SuggestRefMut};
use crate::fn_ctxt::arg_matrix::{ArgMatrix, Compatibility, Error, ExpectedIdx, ProvidedIdx};
use crate::gather_locals::Declaration;
use crate::inline_asm::InlineAsmCtxt;
Expand Down Expand Up @@ -982,23 +982,62 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
err.emit()
}

fn suggest_ptr_null_mut(
fn suggest_mut_addr(
&self,
expected_ty: Ty<'tcx>,
provided_ty: Ty<'tcx>,
arg: &hir::Expr<'tcx>,
err: &mut Diag<'_>,
) {
if let ty::RawPtr(_, hir::Mutability::Mut) = expected_ty.kind()
&& let ty::RawPtr(_, hir::Mutability::Not) = provided_ty.kind()
&& let hir::ExprKind::Call(callee, _) = arg.kind
&& let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = callee.kind
&& let Res::Def(_, def_id) = path.res
&& self.tcx.get_diagnostic_item(sym::ptr_null) == Some(def_id)
{
match (expected_ty.kind(), provided_ty.kind(), arg.kind) {
// The user provided `ptr::null()`, but the function expects
// `ptr::null_mut()`.
err.subdiagnostic(SuggestPtrNullMut { span: arg.span });
(
ty::RawPtr(_, hir::Mutability::Mut),
ty::RawPtr(_, hir::Mutability::Not),
hir::ExprKind::Call(callee, _),
) if let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = callee.kind
&& let Res::Def(_, def_id) = path.res
&& self.tcx.get_diagnostic_item(sym::ptr_null) == Some(def_id) =>
{
err.subdiagnostic(SuggestPtrNullMut { span: arg.span });
}
// &mut T expected, &T or *const/mut T found
// suggestion: replace `&` or `&raw const/mut` with `&mut`
(
ty::Ref(_, expected_ty, hir::Mutability::Mut),
ty::Ref(_, provided_ty, hir::Mutability::Not),
hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, expr),
)
| (
ty::Ref(_, expected_ty, hir::Mutability::Mut),
ty::RawPtr(provided_ty, _),
hir::ExprKind::AddrOf(hir::BorrowKind::Raw, _, expr),
) if expected_ty == provided_ty => {
let span = arg.span.until(expr.span);
err.subdiagnostic(SuggestRefMut { span });
}
// *mut T expected, *const T found
// suggestion: replace `&raw const` with `&raw mut`
(
ty::RawPtr(expected_ty, hir::Mutability::Mut),
ty::RawPtr(provided_ty, hir::Mutability::Not),
hir::ExprKind::AddrOf(hir::BorrowKind::Raw, hir::Mutability::Not, expr),
) if expected_ty == provided_ty => {
let span = arg.span.until(expr.span);
err.subdiagnostic(SuggestRawMut { span });
}
// *mut T expected, &T found
// suggestion: replace `&` `&mut`
(
ty::RawPtr(expected_ty, hir::Mutability::Mut),
ty::Ref(_, provided_ty, hir::Mutability::Not),
hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, expr),
) if expected_ty == provided_ty => {
let span = arg.span.until(expr.span);
err.subdiagnostic(SuggestRefMut { span });
}
_ => {}
}
}

Expand Down Expand Up @@ -2491,7 +2530,7 @@ impl<'a, 'tcx> FnCallDiagCtxt<'a, 'tcx> {
);
}

self.suggest_ptr_null_mut(
self.suggest_mut_addr(
expected_ty,
provided_ty,
self.provided_args[provided_idx],
Expand Down
10 changes: 10 additions & 0 deletions tests/ui/span/coerce-suggestions.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ fn test(_x: &mut String) {}

fn test2(_x: &mut i32) {}

fn test3(_x: *mut String) {}

fn main() {
let x: usize = String::new();
Expand All @@ -11,9 +12,18 @@ fn main() {
let y = String::new();
test(&y);
//~^ ERROR E0308
test(&raw const y);
//~^ ERROR E0308
test(&raw mut y);
//~^ ERROR E0308
test2(&y);
//~^ ERROR E0308
let s = &mut String::new();
s = format!("foo");
//~^ ERROR E0308
let s = String::new();
test3(&raw const s);
//~^ ERROR E0308
test3(&s);
//~^ ERROR E0308
}
99 changes: 93 additions & 6 deletions tests/ui/span/coerce-suggestions.stderr
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Original file line number Diff line number Diff line change
@@ -1,13 +1,13 @@
error[E0308]: mismatched types
--> $DIR/coerce-suggestions.rs:7:20
--> $DIR/coerce-suggestions.rs:8:20
|
LL | let x: usize = String::new();
| ----- ^^^^^^^^^^^^^ expected `usize`, found `String`
| |
| expected due to this

error[E0308]: mismatched types
--> $DIR/coerce-suggestions.rs:9:19
--> $DIR/coerce-suggestions.rs:10:19
|
LL | let x: &str = String::new();
| ---- ^^^^^^^^^^^^^ expected `&str`, found `String`
Expand All @@ -20,7 +20,7 @@ LL | let x: &str = &String::new();
| +

error[E0308]: mismatched types
--> $DIR/coerce-suggestions.rs:12:10
--> $DIR/coerce-suggestions.rs:13:10
|
LL | test(&y);
| ---- ^^ types differ in mutability
Expand All @@ -34,9 +34,55 @@ note: function defined here
|
LL | fn test(_x: &mut String) {}
| ^^^^ ---------------
help: consider using `&mut` instead
|
LL | test(&mut y);
| +++

error[E0308]: mismatched types
--> $DIR/coerce-suggestions.rs:14:11
--> $DIR/coerce-suggestions.rs:15:10
|
LL | test(&raw const y);
| ---- ^^^^^^^^^^^^ expected `&mut String`, found `*const String`
| |
| arguments to this function are incorrect
|
= note: expected mutable reference `&mut String`
found raw pointer `*const String`
note: function defined here
--> $DIR/coerce-suggestions.rs:1:4
|
LL | fn test(_x: &mut String) {}
| ^^^^ ---------------
help: consider using `&mut` instead
|
LL - test(&raw const y);
LL + test(&mut y);
|

error[E0308]: mismatched types
--> $DIR/coerce-suggestions.rs:17:10
|
LL | test(&raw mut y);
| ---- ^^^^^^^^^^ expected `&mut String`, found `*mut String`
| |
| arguments to this function are incorrect
|
= note: expected mutable reference `&mut String`
found raw pointer `*mut String`
note: function defined here
--> $DIR/coerce-suggestions.rs:1:4
|
LL | fn test(_x: &mut String) {}
| ^^^^ ---------------
help: consider using `&mut` instead
|
LL - test(&raw mut y);
LL + test(&mut y);
|

error[E0308]: mismatched types
--> $DIR/coerce-suggestions.rs:19:11
|
LL | test2(&y);
| ----- ^^ types differ in mutability
Expand All @@ -52,11 +98,52 @@ LL | fn test2(_x: &mut i32) {}
| ^^^^^ ------------

error[E0308]: mismatched types
--> $DIR/coerce-suggestions.rs:17:9
--> $DIR/coerce-suggestions.rs:22:9
|
LL | s = format!("foo");
| ^^^^^^^^^^^^^^ expected `&mut String`, found `String`

error: aborting due to 5 previous errors
error[E0308]: mismatched types
--> $DIR/coerce-suggestions.rs:25:11
|
LL | test3(&raw const s);
| ----- ^^^^^^^^^^^^ types differ in mutability
| |
| arguments to this function are incorrect
|
= note: expected raw pointer `*mut String`
found raw pointer `*const String`
note: function defined here
--> $DIR/coerce-suggestions.rs:5:4
|
LL | fn test3(_x: *mut String) {}
| ^^^^^ ---------------
help: consider using `&raw mut` instead
|
LL - test3(&raw const s);
LL + test3(&raw mut s);
|

error[E0308]: mismatched types
--> $DIR/coerce-suggestions.rs:27:11
|
LL | test3(&s);
| ----- ^^ types differ in mutability
| |
| arguments to this function are incorrect
|
= note: expected raw pointer `*mut String`
found reference `&String`
note: function defined here
--> $DIR/coerce-suggestions.rs:5:4
|
LL | fn test3(_x: *mut String) {}
| ^^^^^ ---------------
help: consider using `&mut` instead
|
LL | test3(&mut s);
| +++

error: aborting due to 9 previous errors

For more information about this error, try `rustc --explain E0308`.
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