Suggest using `ptr::null_mut` when user provided `ptr::null` to a function expec...
source link: https://github.com/rust-lang/rust/pull/112302
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Suggest using ptr::null_mut when user provided ptr::null to a function expecting ptr::null_mut
#112302
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error[E0308]: mismatched types
--> $DIR/ptr-null-mutability-suggestions.rs:9:24
|
LL | expecting_null_mut(ptr::null());
| ------------------ ^^^^^^^^^^^
| | |
| | types differ in mutability
| | help: consider using `core::ptr::null_mut` instead: `core::ptr::null_mut()`
| arguments to this function are incorrect
|
= note: expected raw pointer `*mut u8`
found raw pointer `*const _`
note: function defined here
--> $DIR/ptr-null-mutability-suggestions.rs:6:4
|
LL | fn expecting_null_mut(_: *mut u8) {}
| ^^^^^^^^^^^^^^^^^^ ----------
Closes #85184.
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|
r? @TaKO8Ki (rustbot has picked a reviewer for you, use r? to override) |
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Comment on lines
1282 to 1301
if let ty::RawPtr(ty::TypeAndMut { mutbl: expected_mutbl, .. }) = expected_ty.kind() |
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&& let ty::RawPtr(ty::TypeAndMut { mutbl: provided_mutbl, .. }) = provided_ty.kind() |
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&& let provided_arg_expr = *provided_args[provided_idx] |
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&& let hir::ExprKind::Call(callee, _) = provided_arg_expr.kind |
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&& let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = callee.kind |
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&& let Res::Def(_, def_id) = path.res |
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{ |
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match (expected_mutbl, provided_mutbl) { |
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(hir::Mutability::Mut, hir::Mutability::Not) => { |
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if let Some(ptr_null_def_id) = self.tcx.get_diagnostic_item(sym::ptr_null) |
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&& def_id == ptr_null_def_id |
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{ |
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// The user provided `ptr::null()`, but the function expects |
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// `ptr::null_mut()`. |
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err.subdiagnostic(SuggestPtrNullMut { |
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span: provided_arg_expr.span |
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}); |
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} |
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}, |
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_ => {}, |
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} |
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} |
You can simplify the condition quite a lot, maybe something like
| if let ty::RawPtr(ty::TypeAndMut { mutbl: expected_mutbl, .. }) = expected_ty.kind() | |
| && let ty::RawPtr(ty::TypeAndMut { mutbl: provided_mutbl, .. }) = provided_ty.kind() | |
| && let provided_arg_expr = *provided_args[provided_idx] | |
| && let hir::ExprKind::Call(callee, _) = provided_arg_expr.kind | |
| && let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = callee.kind | |
| && let Res::Def(_, def_id) = path.res | |
| { | |
| match (expected_mutbl, provided_mutbl) { | |
| (hir::Mutability::Mut, hir::Mutability::Not) => { | |
| if let Some(ptr_null_def_id) = self.tcx.get_diagnostic_item(sym::ptr_null) | |
| && def_id == ptr_null_def_id | |
| { | |
| // The user provided `ptr::null()`, but the function expects | |
| // `ptr::null_mut()`. | |
| err.subdiagnostic(SuggestPtrNullMut { | |
| span: provided_arg_expr.span | |
| }); | |
| } | |
| }, | |
| _ => {}, | |
| } | |
| } | |
| if let ty::RawPtr(ty::TypeAndMut { mutbl: hir::Mutability::Mut, .. }) = expected_ty.kind() | |
| && let ty::RawPtr(ty::TypeAndMut { mutbl: hir::Mutability::Not, .. }) = provided_ty.kind() | |
| && let provided_arg_expr = *provided_args[provided_idx] | |
| && let hir::ExprKind::Call(callee, _) = provided_arg_expr.kind | |
| && let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = callee.kind | |
| && let Res::Def(_, def_id) = path.res | |
| && Some(def_id) == self.tcx.get_diagnostic_item(sym::ptr_null) | |
| { | |
| // The user provided `ptr::null()`, but the function expects | |
| // `ptr::null_mut()`. | |
| err.subdiagnostic(SuggestPtrNullMut { | |
| span: provided_arg_expr.span | |
| }); | |
| } |
added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author.
and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties.
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@rustbot ready |
added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties.
and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author.
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&& *expected_mutbl == hir::Mutability::Mut |
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&& *provided_mutbl == hir::Mutability::Not |
I'm not sure why you don't want to just ty::RawPtr(ty::TypeAndMut { mutbl: hir::Mutability::Mut, .. }) in the pattern above, as imo it reads quite good: expected_ty is a raw pointer with mut mutability...
But if you don't like to do it in the pattern, at least use .is_mut()/.is_not() and move those two checks to the top, just after the corresponding let raw_ptr = ty.kind()-ish code.
Comment on lines
1294 to 1295
&& let Some(ptr_null_def_id) = self.tcx.get_diagnostic_item(sym::ptr_null) |
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&& def_id == ptr_null_def_id |
| && let Some(ptr_null_def_id) = self.tcx.get_diagnostic_item(sym::ptr_null) | |
| && def_id == ptr_null_def_id | |
| && Some(def_id) == self.tcx.get_diagnostic_item(sym::ptr_null) |
or maybe
| && let Some(ptr_null_def_id) = self.tcx.get_diagnostic_item(sym::ptr_null) | |
| && def_id == ptr_null_def_id | |
| && self.tcx.get_diagnostic_item(sym::ptr_null) == Some(def_id) |
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@bors r+ rollup |
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and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties.
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Suggestion for diagnostic imoprovement in case of null pointer that differs in mutability
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