Uplift clippy::cast_ref_to_mut to rustc

This commit is contained in:
Urgau 2023-05-14 16:20:32 +02:00
parent a51ad131e6
commit 5da606779c
6 changed files with 196 additions and 0 deletions

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@ -155,6 +155,8 @@ lint_builtin_unused_doc_comment = unused doc comment
lint_builtin_while_true = denote infinite loops with `loop {"{"} ... {"}"}`
.suggestion = use `loop`
lint_cast_ref_to_mut = casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
lint_check_name_deprecated = lint name `{$lint_name}` is deprecated and does not have an effect anymore. Use: {$new_name}
lint_check_name_unknown = unknown lint: `{$lint_name}`

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@ -0,0 +1,72 @@
use rustc_ast::Mutability;
use rustc_hir::{Expr, ExprKind, MutTy, TyKind, UnOp};
use rustc_middle::ty;
use rustc_span::sym;
use crate::{lints::CastRefToMutDiag, LateContext, LateLintPass, LintContext};
declare_lint! {
/// The `cast_ref_to_mut` lint checks for casts of `&T` to `&mut T`
/// without using interior mutability.
///
/// ### Example
///
/// ```rust,compile_fail
/// fn x(r: &i32) {
/// unsafe {
/// *(r as *const i32 as *mut i32) += 1;
/// }
/// }
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// Casting `&T` to `&mut T` without using interior mutability is undefined behavior,
/// as it's a violation of Rust reference aliasing requirements.
///
/// `UnsafeCell` is the only way to obtain aliasable data that is considered
/// mutable.
CAST_REF_TO_MUT,
Deny,
"casts of `&T` to `&mut T` without interior mutability"
}
declare_lint_pass!(CastRefToMut => [CAST_REF_TO_MUT]);
impl<'tcx> LateLintPass<'tcx> for CastRefToMut {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
let ExprKind::Unary(UnOp::Deref, e) = &expr.kind else { return; };
let e = e.peel_blocks();
let e = if let ExprKind::Cast(e, t) = e.kind
&& let TyKind::Ptr(MutTy { mutbl: Mutability::Mut, .. }) = t.kind {
e
} else if let ExprKind::MethodCall(_, expr, [], _) = e.kind
&& let Some(def_id) = cx.typeck_results().type_dependent_def_id(e.hir_id)
&& cx.tcx.is_diagnostic_item(sym::ptr_cast_mut, def_id) {
expr
} else {
return;
};
let e = e.peel_blocks();
let e = if let ExprKind::Cast(e, t) = e.kind
&& let TyKind::Ptr(MutTy { mutbl: Mutability::Not, .. }) = t.kind {
e
} else if let ExprKind::Call(path, [arg]) = e.kind
&& let ExprKind::Path(ref qpath) = path.kind
&& let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
&& cx.tcx.is_diagnostic_item(sym::ptr_from_ref, def_id) {
arg
} else {
return;
};
let e = e.peel_blocks();
if let ty::Ref(..) = cx.typeck_results().node_type(e.hir_id).kind() {
cx.emit_spanned_lint(CAST_REF_TO_MUT, expr.span, CastRefToMutDiag);
}
}
}

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@ -50,6 +50,7 @@ extern crate tracing;
mod array_into_iter;
pub mod builtin;
mod cast_ref_to_mut;
mod context;
mod deref_into_dyn_supertrait;
mod drop_forget_useless;
@ -97,6 +98,7 @@ use rustc_span::Span;
use array_into_iter::ArrayIntoIter;
use builtin::*;
use cast_ref_to_mut::*;
use deref_into_dyn_supertrait::*;
use drop_forget_useless::*;
use enum_intrinsics_non_enums::EnumIntrinsicsNonEnums;
@ -214,6 +216,7 @@ late_lint_methods!(
BoxPointers: BoxPointers,
PathStatements: PathStatements,
LetUnderscore: LetUnderscore,
CastRefToMut: CastRefToMut,
// Depends on referenced function signatures in expressions
UnusedResults: UnusedResults,
NonUpperCaseGlobals: NonUpperCaseGlobals,

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@ -718,6 +718,11 @@ pub enum InvalidFromUtf8Diag {
},
}
// cast_ref_to_mut.rs
#[derive(LintDiagnostic)]
#[diag(lint_cast_ref_to_mut)]
pub struct CastRefToMutDiag;
// hidden_unicode_codepoints.rs
#[derive(LintDiagnostic)]
#[diag(lint_hidden_unicode_codepoints)]

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@ -0,0 +1,50 @@
// check-fail
#![feature(ptr_from_ref)]
extern "C" {
// N.B., mutability can be easily incorrect in FFI calls -- as
// in C, the default is mutable pointers.
fn ffi(c: *mut u8);
fn int_ffi(c: *mut i32);
}
fn main() {
let s = String::from("Hello");
let a = &s;
unsafe {
let num = &3i32;
let mut_num = &mut 3i32;
(*(a as *const _ as *mut String)).push_str(" world");
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
*(a as *const _ as *mut _) = String::from("Replaced");
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
*(a as *const _ as *mut String) += " world";
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let _num = &mut *(num as *const i32 as *mut i32);
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let _num = &mut *(num as *const i32).cast_mut();
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let _num = *{ num as *const i32 }.cast_mut();
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
*std::ptr::from_ref(num).cast_mut() += 1;
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
*std::ptr::from_ref({ num }).cast_mut() += 1;
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
*{ std::ptr::from_ref(num) }.cast_mut() += 1;
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
*(std::ptr::from_ref({ num }) as *mut i32) += 1;
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
// Shouldn't be warned against
println!("{}", *(num as *const _ as *const i16));
println!("{}", *(mut_num as *mut _ as *mut i16));
ffi(a.as_ptr() as *mut _);
int_ffi(num as *const _ as *mut _);
int_ffi(&3 as *const _ as *mut _);
let mut value = 3;
let value: *const i32 = &mut value;
*(value as *const i16 as *mut i16) = 42;
}
}

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@ -0,0 +1,64 @@
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/cast_ref_to_mut.rs:19:9
|
LL | (*(a as *const _ as *mut String)).push_str(" world");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `#[deny(cast_ref_to_mut)]` on by default
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/cast_ref_to_mut.rs:21:9
|
LL | *(a as *const _ as *mut _) = String::from("Replaced");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/cast_ref_to_mut.rs:23:9
|
LL | *(a as *const _ as *mut String) += " world";
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/cast_ref_to_mut.rs:25:25
|
LL | let _num = &mut *(num as *const i32 as *mut i32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/cast_ref_to_mut.rs:27:25
|
LL | let _num = &mut *(num as *const i32).cast_mut();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/cast_ref_to_mut.rs:29:20
|
LL | let _num = *{ num as *const i32 }.cast_mut();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/cast_ref_to_mut.rs:31:9
|
LL | *std::ptr::from_ref(num).cast_mut() += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/cast_ref_to_mut.rs:33:9
|
LL | *std::ptr::from_ref({ num }).cast_mut() += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/cast_ref_to_mut.rs:35:9
|
LL | *{ std::ptr::from_ref(num) }.cast_mut() += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/cast_ref_to_mut.rs:37:9
|
LL | *(std::ptr::from_ref({ num }) as *mut i32) += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 10 previous errors