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Auto merge of rust-lang#124895 - obeis:static-mut-hidden-ref, r=compi…
…ler-errors Disallow hidden references to mutable static Closes rust-lang#123060 Tracking: - rust-lang#123758
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Original file line number | Diff line number | Diff line change |
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use rustc_hir as hir; | ||
use rustc_hir::{Expr, Stmt}; | ||
use rustc_middle::ty::{Mutability, TyKind}; | ||
use rustc_session::lint::FutureIncompatibilityReason; | ||
use rustc_session::{declare_lint, declare_lint_pass}; | ||
use rustc_span::edition::Edition; | ||
use rustc_span::Span; | ||
|
||
use crate::lints::{MutRefSugg, RefOfMutStatic}; | ||
use crate::{LateContext, LateLintPass, LintContext}; | ||
|
||
declare_lint! { | ||
/// The `static_mut_refs` lint checks for shared or mutable references | ||
/// of mutable static inside `unsafe` blocks and `unsafe` functions. | ||
/// | ||
/// ### Example | ||
/// | ||
/// ```rust,edition2021 | ||
/// fn main() { | ||
/// static mut X: i32 = 23; | ||
/// static mut Y: i32 = 24; | ||
/// | ||
/// unsafe { | ||
/// let y = &X; | ||
/// let ref x = X; | ||
/// let (x, y) = (&X, &Y); | ||
/// foo(&X); | ||
/// } | ||
/// } | ||
/// | ||
/// unsafe fn _foo() { | ||
/// static mut X: i32 = 23; | ||
/// static mut Y: i32 = 24; | ||
/// | ||
/// let y = &X; | ||
/// let ref x = X; | ||
/// let (x, y) = (&X, &Y); | ||
/// foo(&X); | ||
/// } | ||
/// | ||
/// fn foo<'a>(_x: &'a i32) {} | ||
/// ``` | ||
/// | ||
/// {{produces}} | ||
/// | ||
/// ### Explanation | ||
/// | ||
/// Shared or mutable references of mutable static are almost always a mistake and | ||
/// can lead to undefined behavior and various other problems in your code. | ||
/// | ||
/// This lint is "warn" by default on editions up to 2021, in 2024 is "deny". | ||
pub STATIC_MUT_REFS, | ||
Warn, | ||
"shared references or mutable references of mutable static is discouraged", | ||
@future_incompatible = FutureIncompatibleInfo { | ||
reason: FutureIncompatibilityReason::EditionError(Edition::Edition2024), | ||
reference: "<https://doc.rust-lang.org/nightly/edition-guide/rust-2024/static-mut-references.html>", | ||
explain_reason: false, | ||
}; | ||
@edition Edition2024 => Deny; | ||
} | ||
|
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declare_lint_pass!(StaticMutRefs => [STATIC_MUT_REFS]); | ||
|
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impl<'tcx> LateLintPass<'tcx> for StaticMutRefs { | ||
#[allow(rustc::usage_of_ty_tykind)] | ||
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'_>) { | ||
let err_span = expr.span; | ||
match expr.kind { | ||
hir::ExprKind::AddrOf(borrow_kind, m, ex) | ||
if matches!(borrow_kind, hir::BorrowKind::Ref) | ||
&& let Some(err_span) = path_is_static_mut(ex, err_span) => | ||
{ | ||
emit_static_mut_refs( | ||
cx, | ||
err_span, | ||
err_span.with_hi(ex.span.lo()), | ||
m, | ||
!expr.span.from_expansion(), | ||
); | ||
} | ||
hir::ExprKind::MethodCall(_, e, _, _) | ||
if let Some(err_span) = path_is_static_mut(e, expr.span) | ||
&& let typeck = cx.typeck_results() | ||
&& let Some(method_def_id) = typeck.type_dependent_def_id(expr.hir_id) | ||
&& let inputs = | ||
cx.tcx.fn_sig(method_def_id).skip_binder().inputs().skip_binder() | ||
&& let Some(receiver) = inputs.get(0) | ||
&& let TyKind::Ref(_, _, m) = receiver.kind() => | ||
{ | ||
emit_static_mut_refs(cx, err_span, err_span.shrink_to_lo(), *m, false); | ||
} | ||
_ => {} | ||
} | ||
} | ||
|
||
fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &Stmt<'_>) { | ||
if let hir::StmtKind::Let(loc) = stmt.kind | ||
&& let hir::PatKind::Binding(ba, _, _, _) = loc.pat.kind | ||
&& let hir::ByRef::Yes(m) = ba.0 | ||
&& let Some(init) = loc.init | ||
&& let Some(err_span) = path_is_static_mut(init, init.span) | ||
{ | ||
emit_static_mut_refs(cx, err_span, err_span.shrink_to_lo(), m, false); | ||
} | ||
} | ||
} | ||
|
||
fn path_is_static_mut(mut expr: &hir::Expr<'_>, mut err_span: Span) -> Option<Span> { | ||
if err_span.from_expansion() { | ||
err_span = expr.span; | ||
} | ||
|
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while let hir::ExprKind::Field(e, _) = expr.kind { | ||
expr = e; | ||
} | ||
|
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if let hir::ExprKind::Path(qpath) = expr.kind | ||
&& let hir::QPath::Resolved(_, path) = qpath | ||
&& let hir::def::Res::Def(def_kind, _) = path.res | ||
&& let hir::def::DefKind::Static { safety: _, mutability: Mutability::Mut, nested: false } = | ||
def_kind | ||
{ | ||
return Some(err_span); | ||
} | ||
None | ||
} | ||
|
||
fn emit_static_mut_refs( | ||
cx: &LateContext<'_>, | ||
span: Span, | ||
sugg_span: Span, | ||
mutable: Mutability, | ||
suggest_addr_of: bool, | ||
) { | ||
let (shared_label, shared_note, mut_note, sugg) = match mutable { | ||
Mutability::Mut => { | ||
let sugg = | ||
if suggest_addr_of { Some(MutRefSugg::Mut { span: sugg_span }) } else { None }; | ||
("mutable ", false, true, sugg) | ||
} | ||
Mutability::Not => { | ||
let sugg = | ||
if suggest_addr_of { Some(MutRefSugg::Shared { span: sugg_span }) } else { None }; | ||
("shared ", true, false, sugg) | ||
} | ||
}; | ||
|
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cx.emit_span_lint( | ||
STATIC_MUT_REFS, | ||
span, | ||
RefOfMutStatic { span, sugg, shared_label, shared_note, mut_note }, | ||
); | ||
} |
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