Add support for deferred casting for the invalid_reference_casting lint
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@ -319,6 +319,7 @@ lint_invalid_nan_comparisons_eq_ne = incorrect NaN comparison, NaN cannot be dir
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lint_invalid_nan_comparisons_lt_le_gt_ge = incorrect NaN comparison, NaN is not orderable
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lint_invalid_reference_casting = casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
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.label = casting happend here
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lint_lintpass_by_hand = implementing `LintPass` by hand
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.help = try using `declare_lint_pass!` or `impl_lint_pass!` instead
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@ -218,7 +218,7 @@ fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
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BoxPointers: BoxPointers,
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PathStatements: PathStatements,
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LetUnderscore: LetUnderscore,
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InvalidReferenceCasting: InvalidReferenceCasting,
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InvalidReferenceCasting: InvalidReferenceCasting::default(),
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// Depends on referenced function signatures in expressions
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UnusedResults: UnusedResults,
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NonUpperCaseGlobals: NonUpperCaseGlobals,
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@ -746,7 +746,10 @@ pub enum InvalidFromUtf8Diag {
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// reference_casting.rs
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#[derive(LintDiagnostic)]
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#[diag(lint_invalid_reference_casting)]
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pub struct InvalidReferenceCastingDiag;
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pub struct InvalidReferenceCastingDiag {
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#[label]
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pub orig_cast: Option<Span>,
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}
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// hidden_unicode_codepoints.rs
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#[derive(LintDiagnostic)]
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@ -1,7 +1,8 @@
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use rustc_ast::Mutability;
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use rustc_hir::{Expr, ExprKind, MutTy, TyKind, UnOp};
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use rustc_middle::ty;
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use rustc_span::sym;
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use rustc_data_structures::fx::FxHashMap;
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use rustc_hir::{def::Res, Expr, ExprKind, HirId, Local, QPath, StmtKind, UnOp};
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use rustc_middle::ty::{self, TypeAndMut};
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use rustc_span::{sym, Span};
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use crate::{lints::InvalidReferenceCastingDiag, LateContext, LateLintPass, LintContext};
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@ -33,42 +34,74 @@
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"casts of `&T` to `&mut T` without interior mutability"
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}
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declare_lint_pass!(InvalidReferenceCasting => [INVALID_REFERENCE_CASTING]);
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#[derive(Default)]
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pub struct InvalidReferenceCasting {
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casted: FxHashMap<HirId, Span>,
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}
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impl_lint_pass!(InvalidReferenceCasting => [INVALID_REFERENCE_CASTING]);
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impl<'tcx> LateLintPass<'tcx> for InvalidReferenceCasting {
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fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx rustc_hir::Stmt<'tcx>) {
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let StmtKind::Local(local) = stmt.kind else {
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return;
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};
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let Local { init: Some(init), els: None, .. } = local else {
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return;
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};
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if is_cast_from_const_to_mut(cx, init) {
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self.casted.insert(local.pat.hir_id, init.span);
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}
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}
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
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let ExprKind::Unary(UnOp::Deref, e) = &expr.kind else {
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return;
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};
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if is_cast_from_const_to_mut(cx, e) {
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cx.emit_spanned_lint(INVALID_REFERENCE_CASTING, expr.span, InvalidReferenceCastingDiag { orig_cast: None });
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} else if let ExprKind::Path(QPath::Resolved(_, path)) = e.kind
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&& let Res::Local(hir_id) = &path.res
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&& let Some(orig_cast) = self.casted.get(hir_id) {
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cx.emit_spanned_lint(INVALID_REFERENCE_CASTING, expr.span, InvalidReferenceCastingDiag { orig_cast: Some(*orig_cast) });
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}
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}
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}
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fn is_cast_from_const_to_mut<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'tcx>) -> bool {
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let e = e.peel_blocks();
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// <expr> as *mut ...
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let e = if let ExprKind::Cast(e, t) = e.kind
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&& let TyKind::Ptr(MutTy { mutbl: Mutability::Mut, .. }) = t.kind {
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&& let ty::RawPtr(TypeAndMut { mutbl: Mutability::Mut, .. }) = cx.typeck_results().node_type(t.hir_id).kind() {
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e
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// <expr>.cast_mut()
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} else if let ExprKind::MethodCall(_, expr, [], _) = e.kind
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&& let Some(def_id) = cx.typeck_results().type_dependent_def_id(e.hir_id)
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&& cx.tcx.is_diagnostic_item(sym::ptr_cast_mut, def_id) {
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expr
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} else {
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return;
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return false;
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};
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let e = e.peel_blocks();
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// <expr> as *const ...
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let e = if let ExprKind::Cast(e, t) = e.kind
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&& let TyKind::Ptr(MutTy { mutbl: Mutability::Not, .. }) = t.kind {
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&& let ty::RawPtr(TypeAndMut { mutbl: Mutability::Not, .. }) = cx.typeck_results().node_type(t.hir_id).kind() {
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e
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// ptr::from_ref(<expr>)
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} else if let ExprKind::Call(path, [arg]) = e.kind
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&& let ExprKind::Path(ref qpath) = path.kind
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&& let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
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&& cx.tcx.is_diagnostic_item(sym::ptr_from_ref, def_id) {
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arg
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} else {
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return;
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return false;
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};
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let e = e.peel_blocks();
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if let ty::Ref(..) = cx.typeck_results().node_type(e.hir_id).kind() {
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cx.emit_spanned_lint(INVALID_REFERENCE_CASTING, expr.span, InvalidReferenceCastingDiag);
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}
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}
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matches!(cx.typeck_results().node_type(e.hir_id).kind(), ty::Ref(..))
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}
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@ -36,6 +36,9 @@ fn main() {
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//~^ ERROR casting `&T` to `&mut T` is undefined behavior
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*(std::ptr::from_ref({ num }) as *mut i32) += 1;
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//~^ ERROR casting `&T` to `&mut T` is undefined behavior
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let value = num as *const i32 as *mut i32;
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*value = 1;
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//~^ ERROR casting `&T` to `&mut T` is undefined behavior
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// Shouldn't be warned against
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println!("{}", *(num as *const _ as *const i16));
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@ -60,5 +60,13 @@ error: casting `&T` to `&mut T` is undefined behavior, even if the reference is
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LL | *(std::ptr::from_ref({ num }) as *mut i32) += 1;
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: aborting due to 10 previous errors
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error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
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--> $DIR/reference_casting.rs:40:9
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LL | let value = num as *const i32 as *mut i32;
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| ----------------------------- casting happend here
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LL | *value = 1;
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| ^^^^^^
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error: aborting due to 11 previous errors
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