Add support for deferred casting for the invalid_reference_casting lint

This commit is contained in:
Urgau 2023-07-14 22:10:14 +02:00
parent 345d6b816b
commit f3dafe91ff
6 changed files with 83 additions and 35 deletions

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@ -319,6 +319,7 @@ lint_invalid_nan_comparisons_eq_ne = incorrect NaN comparison, NaN cannot be dir
lint_invalid_nan_comparisons_lt_le_gt_ge = incorrect NaN comparison, NaN is not orderable
lint_invalid_reference_casting = casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
.label = casting happend here
lint_lintpass_by_hand = implementing `LintPass` by hand
.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) {
BoxPointers: BoxPointers,
PathStatements: PathStatements,
LetUnderscore: LetUnderscore,
InvalidReferenceCasting: InvalidReferenceCasting,
InvalidReferenceCasting: InvalidReferenceCasting::default(),
// Depends on referenced function signatures in expressions
UnusedResults: UnusedResults,
NonUpperCaseGlobals: NonUpperCaseGlobals,

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@ -746,7 +746,10 @@ pub enum InvalidFromUtf8Diag {
// reference_casting.rs
#[derive(LintDiagnostic)]
#[diag(lint_invalid_reference_casting)]
pub struct InvalidReferenceCastingDiag;
pub struct InvalidReferenceCastingDiag {
#[label]
pub orig_cast: Option<Span>,
}
// hidden_unicode_codepoints.rs
#[derive(LintDiagnostic)]

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@ -1,7 +1,8 @@
use rustc_ast::Mutability;
use rustc_hir::{Expr, ExprKind, MutTy, TyKind, UnOp};
use rustc_middle::ty;
use rustc_span::sym;
use rustc_data_structures::fx::FxHashMap;
use rustc_hir::{def::Res, Expr, ExprKind, HirId, Local, QPath, StmtKind, UnOp};
use rustc_middle::ty::{self, TypeAndMut};
use rustc_span::{sym, Span};
use crate::{lints::InvalidReferenceCastingDiag, LateContext, LateLintPass, LintContext};
@ -33,42 +34,74 @@
"casts of `&T` to `&mut T` without interior mutability"
}
declare_lint_pass!(InvalidReferenceCasting => [INVALID_REFERENCE_CASTING]);
#[derive(Default)]
pub struct InvalidReferenceCasting {
casted: FxHashMap<HirId, Span>,
}
impl_lint_pass!(InvalidReferenceCasting => [INVALID_REFERENCE_CASTING]);
impl<'tcx> LateLintPass<'tcx> for InvalidReferenceCasting {
fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx rustc_hir::Stmt<'tcx>) {
let StmtKind::Local(local) = stmt.kind else {
return;
};
let Local { init: Some(init), els: None, .. } = local else {
return;
};
if is_cast_from_const_to_mut(cx, init) {
self.casted.insert(local.pat.hir_id, init.span);
}
}
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
let ExprKind::Unary(UnOp::Deref, e) = &expr.kind else {
return;
};
if is_cast_from_const_to_mut(cx, e) {
cx.emit_spanned_lint(INVALID_REFERENCE_CASTING, expr.span, InvalidReferenceCastingDiag { orig_cast: None });
} else if let ExprKind::Path(QPath::Resolved(_, path)) = e.kind
&& let Res::Local(hir_id) = &path.res
&& let Some(orig_cast) = self.casted.get(hir_id) {
cx.emit_spanned_lint(INVALID_REFERENCE_CASTING, expr.span, InvalidReferenceCastingDiag { orig_cast: Some(*orig_cast) });
}
}
}
fn is_cast_from_const_to_mut<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'tcx>) -> bool {
let e = e.peel_blocks();
// <expr> as *mut ...
let e = if let ExprKind::Cast(e, t) = e.kind
&& let TyKind::Ptr(MutTy { mutbl: Mutability::Mut, .. }) = t.kind {
&& let ty::RawPtr(TypeAndMut { mutbl: Mutability::Mut, .. }) = cx.typeck_results().node_type(t.hir_id).kind() {
e
// <expr>.cast_mut()
} 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;
return false;
};
let e = e.peel_blocks();
// <expr> as *const ...
let e = if let ExprKind::Cast(e, t) = e.kind
&& let TyKind::Ptr(MutTy { mutbl: Mutability::Not, .. }) = t.kind {
&& let ty::RawPtr(TypeAndMut { mutbl: Mutability::Not, .. }) = cx.typeck_results().node_type(t.hir_id).kind() {
e
// ptr::from_ref(<expr>)
} 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;
return false;
};
let e = e.peel_blocks();
if let ty::Ref(..) = cx.typeck_results().node_type(e.hir_id).kind() {
cx.emit_spanned_lint(INVALID_REFERENCE_CASTING, expr.span, InvalidReferenceCastingDiag);
}
}
matches!(cx.typeck_results().node_type(e.hir_id).kind(), ty::Ref(..))
}

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@ -36,6 +36,9 @@ fn main() {
//~^ 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
let value = num as *const i32 as *mut i32;
*value = 1;
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
// Shouldn't be warned against
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
LL | *(std::ptr::from_ref({ num }) as *mut i32) += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 10 previous errors
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:40:9
|
LL | let value = num as *const i32 as *mut i32;
| ----------------------------- casting happend here
LL | *value = 1;
| ^^^^^^
error: aborting due to 11 previous errors