diff options
| -rw-r--r-- | clippy_lints/src/casts/cast_ref_to_mut.rs | 28 | ||||
| -rw-r--r-- | clippy_lints/src/casts/mod.rs | 99 | ||||
| -rw-r--r-- | clippy_lints/src/lib.rs | 1 |
3 files changed, 68 insertions, 60 deletions
diff --git a/clippy_lints/src/casts/cast_ref_to_mut.rs b/clippy_lints/src/casts/cast_ref_to_mut.rs new file mode 100644 index 00000000000..3fdc1c6168b --- /dev/null +++ b/clippy_lints/src/casts/cast_ref_to_mut.rs @@ -0,0 +1,28 @@ +use rustc_hir::{Expr, ExprKind, MutTy, Mutability, TyKind, UnOp}; +use rustc_lint::LateContext; +use rustc_middle::ty; + +use if_chain::if_chain; + +use crate::utils::span_lint; + +use super::CAST_REF_TO_MUT; + +pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { + if_chain! { + if let ExprKind::Unary(UnOp::Deref, e) = &expr.kind; + if let ExprKind::Cast(e, t) = &e.kind; + if let TyKind::Ptr(MutTy { mutbl: Mutability::Mut, .. }) = t.kind; + if let ExprKind::Cast(e, t) = &e.kind; + if let TyKind::Ptr(MutTy { mutbl: Mutability::Not, .. }) = t.kind; + if let ty::Ref(..) = cx.typeck_results().node_type(e.hir_id).kind(); + then { + span_lint( + cx, + CAST_REF_TO_MUT, + expr.span, + "casting `&T` to `&mut T` may cause undefined behavior, consider instead using an `UnsafeCell`", + ); + } + } +} diff --git a/clippy_lints/src/casts/mod.rs b/clippy_lints/src/casts/mod.rs index cf8a64e1fd8..7d5ada18be3 100644 --- a/clippy_lints/src/casts/mod.rs +++ b/clippy_lints/src/casts/mod.rs @@ -3,6 +3,7 @@ mod cast_possible_truncation; mod cast_possible_wrap; mod cast_precision_loss; mod cast_ptr_alignment; +mod cast_ref_to_mut; mod cast_sign_loss; mod fn_to_numeric_cast; mod fn_to_numeric_cast_with_truncation; @@ -14,7 +15,7 @@ use std::borrow::Cow; use if_chain::if_chain; use rustc_ast::LitKind; use rustc_errors::Applicability; -use rustc_hir::{Expr, ExprKind, MutTy, Mutability, TyKind, UnOp}; +use rustc_hir::{Expr, ExprKind, Mutability, TyKind}; use rustc_lint::{LateContext, LateLintPass, LintContext}; use rustc_middle::lint::in_external_macro; use rustc_middle::ty::{self, TypeAndMut, UintTy}; @@ -23,7 +24,7 @@ use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass}; use crate::utils::sugg::Sugg; use crate::utils::{ - is_hir_ty_cfg_dependant, meets_msrv, snippet_with_applicability, span_lint, span_lint_and_sugg, span_lint_and_then, + is_hir_ty_cfg_dependant, meets_msrv, snippet_with_applicability, span_lint_and_sugg, span_lint_and_then, }; declare_clippy_lint! { @@ -255,12 +256,47 @@ declare_clippy_lint! { "casting a function pointer to a numeric type not wide enough to store the address" } +declare_clippy_lint! { + /// **What it does:** Checks for casts of `&T` to `&mut T` anywhere in the code. + /// + /// **Why is this bad?** It’s basically guaranteed to be undefined behaviour. + /// `UnsafeCell` is the only way to obtain aliasable data that is considered + /// mutable. + /// + /// **Known problems:** None. + /// + /// **Example:** + /// ```rust,ignore + /// fn x(r: &i32) { + /// unsafe { + /// *(r as *const _ as *mut _) += 1; + /// } + /// } + /// ``` + /// + /// Instead consider using interior mutability types. + /// + /// ```rust + /// use std::cell::UnsafeCell; + /// + /// fn x(r: &UnsafeCell<i32>) { + /// unsafe { + /// *r.get() += 1; + /// } + /// } + /// ``` + pub CAST_REF_TO_MUT, + correctness, + "a cast of reference to a mutable pointer" +} + declare_lint_pass!(Casts => [ CAST_PRECISION_LOSS, CAST_SIGN_LOSS, CAST_POSSIBLE_TRUNCATION, CAST_POSSIBLE_WRAP, CAST_LOSSLESS, + CAST_REF_TO_MUT, UNNECESSARY_CAST, CAST_PTR_ALIGNMENT, FN_TO_NUMERIC_CAST, @@ -269,6 +305,8 @@ declare_lint_pass!(Casts => [ impl<'tcx> LateLintPass<'tcx> for Casts { fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { + cast_ref_to_mut::check(cx, expr); + if expr.span.from_expansion() { return; } @@ -300,63 +338,6 @@ impl<'tcx> LateLintPass<'tcx> for Casts { } } -declare_clippy_lint! { - /// **What it does:** Checks for casts of `&T` to `&mut T` anywhere in the code. - /// - /// **Why is this bad?** It’s basically guaranteed to be undefined behaviour. - /// `UnsafeCell` is the only way to obtain aliasable data that is considered - /// mutable. - /// - /// **Known problems:** None. - /// - /// **Example:** - /// ```rust,ignore - /// fn x(r: &i32) { - /// unsafe { - /// *(r as *const _ as *mut _) += 1; - /// } - /// } - /// ``` - /// - /// Instead consider using interior mutability types. - /// - /// ```rust - /// use std::cell::UnsafeCell; - /// - /// fn x(r: &UnsafeCell<i32>) { - /// unsafe { - /// *r.get() += 1; - /// } - /// } - /// ``` - pub CAST_REF_TO_MUT, - correctness, - "a cast of reference to a mutable pointer" -} - -declare_lint_pass!(RefToMut => [CAST_REF_TO_MUT]); - -impl<'tcx> LateLintPass<'tcx> for RefToMut { - fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { - if_chain! { - if let ExprKind::Unary(UnOp::Deref, e) = &expr.kind; - if let ExprKind::Cast(e, t) = &e.kind; - if let TyKind::Ptr(MutTy { mutbl: Mutability::Mut, .. }) = t.kind; - if let ExprKind::Cast(e, t) = &e.kind; - if let TyKind::Ptr(MutTy { mutbl: Mutability::Not, .. }) = t.kind; - if let ty::Ref(..) = cx.typeck_results().node_type(e.hir_id).kind(); - then { - span_lint( - cx, - CAST_REF_TO_MUT, - expr.span, - "casting `&T` to `&mut T` may cause undefined behavior, consider instead using an `UnsafeCell`", - ); - } - } - } -} - const PTR_AS_PTR_MSRV: RustcVersion = RustcVersion::new(1, 38, 0); declare_clippy_lint! { diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index a46c56a01d5..47afd7beb74 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -1176,7 +1176,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: store.register_late_pass(|| box slow_vector_initialization::SlowVectorInit); store.register_late_pass(|| box unnecessary_sort_by::UnnecessarySortBy); store.register_late_pass(|| box unnecessary_wraps::UnnecessaryWraps); - store.register_late_pass(|| box casts::RefToMut); store.register_late_pass(|| box assertions_on_constants::AssertionsOnConstants); store.register_late_pass(|| box transmuting_null::TransmutingNull); store.register_late_pass(|| box path_buf_push_overwrite::PathBufPushOverwrite); |