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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,70 @@ | ||
| use clippy_utils::{consts::is_promotable, diagnostics::span_lint_and_note, is_from_proc_macro}; | ||
| use rustc_hir::{BorrowKind, Expr, ExprKind, ItemKind, OwnerNode}; | ||
| use rustc_lint::{LateContext, LateLintPass, LintContext}; | ||
| use rustc_middle::lint::in_external_macro; | ||
| use rustc_session::{declare_lint_pass, declare_tool_lint}; | ||
|
|
||
| declare_clippy_lint! { | ||
| /// ### What it does | ||
| /// Checks for raw pointers pointing to temporary values that will **not** be promoted to a | ||
| /// constant through | ||
| /// [constant promotion](https://doc.rust-lang.org/stable/reference/destructors.html#constant-promotion). | ||
| /// | ||
| /// ### Why is this bad? | ||
| /// Usage of such a pointer can result in Undefined Behavior, as the pointer will stop pointing | ||
| /// to valid stack memory once the temporary is dropped. | ||
| /// | ||
| /// ### Example | ||
| /// ```rust,ignore | ||
| /// fn x() -> *const i32 { | ||
| /// let x = 0; | ||
| /// &x as *const i32 | ||
| /// } | ||
| /// | ||
| /// let x = x(); | ||
| /// unsafe { *x }; // ⚠️ | ||
| /// ``` | ||
| #[clippy::version = "1.72.0"] | ||
| pub PTR_TO_TEMPORARY, | ||
| correctness, | ||
| "disallows returning a raw pointer to a temporary value" | ||
| } | ||
| declare_lint_pass!(PtrToTemporary => [PTR_TO_TEMPORARY]); | ||
|
|
||
| impl<'tcx> LateLintPass<'tcx> for PtrToTemporary { | ||
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) { | ||
| if in_external_macro(cx.sess(), expr.span) { | ||
| return; | ||
| } | ||
|
|
||
| // Get the final return statement if this is a return statement, or don't lint | ||
| let expr = if let ExprKind::Ret(Some(expr)) = expr.kind { | ||
| expr | ||
| } else if let OwnerNode::Item(parent) = cx.tcx.hir().owner(cx.tcx.hir().get_parent_item(expr.hir_id)) | ||
| && let ItemKind::Fn(_, _, body) = parent.kind | ||
| && let block = cx.tcx.hir().body(body).value | ||
| && let ExprKind::Block(block, _) = block.kind | ||
| && let Some(final_block_expr) = block.expr | ||
| && final_block_expr.hir_id == expr.hir_id | ||
| { | ||
| expr | ||
| } else { | ||
| return; | ||
| }; | ||
|
|
||
| if let ExprKind::Cast(cast_expr, _) = expr.kind | ||
| && let ExprKind::AddrOf(BorrowKind::Ref, _, e) = cast_expr.kind | ||
| && !is_promotable(cx, e) | ||
| && !is_from_proc_macro(cx, expr) | ||
| { | ||
| span_lint_and_note( | ||
| cx, | ||
| PTR_TO_TEMPORARY, | ||
| expr.span, | ||
| "returning a raw pointer to a temporary value that cannot be promoted to a constant", | ||
| None, | ||
| "usage of this pointer by callers will cause Undefined Behavior", | ||
| ); | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,34 +1,65 @@ | ||
| #![allow(clippy::explicit_auto_deref, clippy::unnecessary_cast, clippy::useless_vec)] | ||
| //@aux-build:proc_macros.rs | ||
| #![allow(clippy::borrow_deref_ref, clippy::deref_addrof, clippy::identity_op, unused)] | ||
| #![warn(clippy::ptr_to_temporary)] | ||
| #![no_main] | ||
|
|
||
| use std::ptr::addr_of; | ||
| #[macro_use] | ||
| extern crate proc_macros; | ||
|
|
||
| fn a() -> i32 { | ||
| 0 | ||
| fn bad_1() -> *const i32 { | ||
| &(100 + *&0) as *const i32 | ||
| } | ||
|
|
||
| struct Vec3 { | ||
| x: f32, | ||
| y: f32, | ||
| z: f32, | ||
| fn bad_2() -> *const i32 { | ||
| let a = 0i32; | ||
| &(*&a) as *const i32 | ||
| } | ||
|
|
||
| fn main() { | ||
| let _p = &0 as *const i32; | ||
| let _p = &a() as *const i32; | ||
| let vec = vec![1]; | ||
| let _p = &vec.len() as *const usize; | ||
| let x = &(1 + 2) as *const i32; | ||
| let x = &(x as *const i32) as *const *const i32; | ||
| fn bad_3() -> *const i32 { | ||
| let a = 0i32; | ||
| &a as *const i32 | ||
| } | ||
|
|
||
| fn bad_4() -> *const i32 { | ||
| let mut a = 0i32; | ||
| &a as *const i32 | ||
| } | ||
|
|
||
| fn bad_5() -> *const i32 { | ||
| const A: &i32 = &1i32; | ||
| let mut a = 0i32; | ||
|
|
||
| // Do not lint... | ||
| let ptr = &Vec3 { x: 1.0, y: 2.0, z: 3.0 }; | ||
| let some_variable = 1i32; | ||
| let x = &(*ptr).x as *const f32; | ||
| let x = &(some_variable) as *const i32; | ||
| if true { | ||
| return &(*A) as *const i32; | ||
| } | ||
| &a as *const i32 | ||
| } | ||
|
|
||
| fn fine_1() -> *const i32 { | ||
| &100 as *const i32 | ||
| } | ||
|
|
||
| fn fine_2() -> *const i32 { | ||
| const A: &i32 = &0i32; | ||
| A as *const i32 | ||
| } | ||
|
|
||
| fn fine_3() -> *const i32 { | ||
| const A: &i32 = &0i32; | ||
| &(*A) as *const i32 | ||
| } | ||
|
|
||
| external! { | ||
| fn fine_external() -> *const i32 { | ||
| let a = 0i32; | ||
| &a as *const i32 | ||
| } | ||
| } | ||
|
|
||
| // ...As `addr_of!` does not report anything out of the ordinary | ||
| let ptr = &Vec3 { x: 1.0, y: 2.0, z: 3.0 }; | ||
| let some_variable = 1i32; | ||
| let x = addr_of!((*ptr).x) as *const f32; | ||
| let x = addr_of!(some_variable); | ||
| with_span! { | ||
| span | ||
| fn fine_proc_macro() -> *const i32 { | ||
| let a = 0i32; | ||
| &a as *const i32 | ||
| } | ||
| } |
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