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Fixes rust-lang#4294
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,32 @@ | ||
use clippy_utils::diagnostics::span_lint_and_then; | ||
use rustc_hir::{Expr, ExprKind, UnOp}; | ||
use rustc_lint::LateContext; | ||
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use super::RAW_ASSIGN_TO_DROP; | ||
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pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, lhs: &'tcx Expr<'_>) { | ||
if let ExprKind::Unary(UnOp::Deref, expr) = lhs.kind | ||
&& let ty = cx.typeck_results().expr_ty(expr) | ||
&& ty.is_unsafe_ptr() | ||
&& let Some(deref_ty) = ty.builtin_deref(true) | ||
&& deref_ty.needs_drop(cx.tcx, cx.typing_env()) | ||
{ | ||
span_lint_and_then( | ||
cx, | ||
RAW_ASSIGN_TO_DROP, | ||
expr.span, | ||
"assignment via raw pointer always executes destructor", | ||
|diag| { | ||
diag.note(format!( | ||
"the destructor defined by `{deref_ty}` is executed during assignment of the new value" | ||
)); | ||
diag.span_label( | ||
expr.span, | ||
"this place may be uninitialized, causing Undefined Behavior when the destructor executes", | ||
); | ||
diag.help("use `std::ptr::write()` to overwrite a (possibly uninitialized) place"); | ||
diag.help("use `std::ptr::drop_in_place()` to drop the previous value if such value exists"); | ||
}, | ||
); | ||
} | ||
} |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,23 @@ | ||
#![warn(clippy::raw_assign_to_drop)] | ||
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fn main() { | ||
unsafe fn foo(r: *mut String, i: *mut i32) { | ||
*r = "foo".to_owned(); | ||
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// no lint on {integer} | ||
*i = 47; | ||
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(*r, *r) = ("foo".to_owned(), "bar".to_owned()); | ||
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(*r, *i) = ("foo".to_owned(), 47); | ||
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let mut x: String = Default::default(); | ||
*(&mut x as *mut _) = "Foo".to_owned(); | ||
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// no lint on `u8` | ||
*x.as_mut_ptr() = b'a'; | ||
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let mut v: Vec<String> = vec![]; | ||
*v.as_mut_ptr() = Default::default(); | ||
} | ||
} |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,64 @@ | ||
error: assignment via raw pointer always executes destructor | ||
--> tests/ui/raw_assign_to_drop.rs:5:10 | ||
| | ||
LL | *r = "foo".to_owned(); | ||
| ^ this place may be uninitialized, causing Undefined Behavior when the destructor executes | ||
| | ||
= note: the destructor defined by `std::string::String` is executed during assignment of the new value | ||
= help: use `std::ptr::write()` to overwrite a (possibly uninitialized) place | ||
= help: use `std::ptr::drop_in_place()` to drop the previous value if such value exists | ||
= note: `-D clippy::raw-assign-to-drop` implied by `-D warnings` | ||
= help: to override `-D warnings` add `#[allow(clippy::raw_assign_to_drop)]` | ||
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error: assignment via raw pointer always executes destructor | ||
--> tests/ui/raw_assign_to_drop.rs:10:11 | ||
| | ||
LL | (*r, *r) = ("foo".to_owned(), "bar".to_owned()); | ||
| ^ this place may be uninitialized, causing Undefined Behavior when the destructor executes | ||
| | ||
= note: the destructor defined by `std::string::String` is executed during assignment of the new value | ||
= help: use `std::ptr::write()` to overwrite a (possibly uninitialized) place | ||
= help: use `std::ptr::drop_in_place()` to drop the previous value if such value exists | ||
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error: assignment via raw pointer always executes destructor | ||
--> tests/ui/raw_assign_to_drop.rs:10:15 | ||
| | ||
LL | (*r, *r) = ("foo".to_owned(), "bar".to_owned()); | ||
| ^ this place may be uninitialized, causing Undefined Behavior when the destructor executes | ||
| | ||
= note: the destructor defined by `std::string::String` is executed during assignment of the new value | ||
= help: use `std::ptr::write()` to overwrite a (possibly uninitialized) place | ||
= help: use `std::ptr::drop_in_place()` to drop the previous value if such value exists | ||
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error: assignment via raw pointer always executes destructor | ||
--> tests/ui/raw_assign_to_drop.rs:12:11 | ||
| | ||
LL | (*r, *i) = ("foo".to_owned(), 47); | ||
| ^ this place may be uninitialized, causing Undefined Behavior when the destructor executes | ||
| | ||
= note: the destructor defined by `std::string::String` is executed during assignment of the new value | ||
= help: use `std::ptr::write()` to overwrite a (possibly uninitialized) place | ||
= help: use `std::ptr::drop_in_place()` to drop the previous value if such value exists | ||
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error: assignment via raw pointer always executes destructor | ||
--> tests/ui/raw_assign_to_drop.rs:15:10 | ||
| | ||
LL | *(&mut x as *mut _) = "Foo".to_owned(); | ||
| ^^^^^^^^^^^^^^^^^^ this place may be uninitialized, causing Undefined Behavior when the destructor executes | ||
| | ||
= note: the destructor defined by `std::string::String` is executed during assignment of the new value | ||
= help: use `std::ptr::write()` to overwrite a (possibly uninitialized) place | ||
= help: use `std::ptr::drop_in_place()` to drop the previous value if such value exists | ||
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error: assignment via raw pointer always executes destructor | ||
--> tests/ui/raw_assign_to_drop.rs:21:10 | ||
| | ||
LL | *v.as_mut_ptr() = Default::default(); | ||
| ^^^^^^^^^^^^^^ this place may be uninitialized, causing Undefined Behavior when the destructor executes | ||
| | ||
= note: the destructor defined by `std::string::String` is executed during assignment of the new value | ||
= help: use `std::ptr::write()` to overwrite a (possibly uninitialized) place | ||
= help: use `std::ptr::drop_in_place()` to drop the previous value if such value exists | ||
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error: aborting due to 6 previous errors | ||
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