use rustc_hir as hir;
use rustc_middle::mir::BorrowKind;
use rustc_middle::thir::*;
-use rustc_middle::ty::{self, ParamEnv, TyCtxt};
+use rustc_middle::ty::{self, ParamEnv, Ty, TyCtxt};
use rustc_session::lint::builtin::{UNSAFE_OP_IN_UNSAFE_FN, UNUSED_UNSAFE};
use rustc_session::lint::Level;
use rustc_span::def_id::{DefId, LocalDefId};
/// The `#[target_feature]` attributes of the body. Used for checking
/// calls to functions with `#[target_feature]` (RFC 2396).
body_target_features: &'tcx Vec<Symbol>,
- in_possible_lhs_union_assign: bool,
+ /// When inside the LHS of an assignment to a field, this is the type
+ /// of the LHS and the span of the assignment expression.
+ assignment_info: Option<(Ty<'tcx>, Span)>,
in_union_destructure: bool,
param_env: ParamEnv<'tcx>,
inside_adt: bool,
}
fn visit_expr(&mut self, expr: &Expr<'tcx>) {
- // could we be in a the LHS of an assignment of a union?
+ // could we be in the LHS of an assignment to a field?
match expr.kind {
ExprKind::Field { .. }
| ExprKind::VarRef { .. }
| ExprKind::InlineAsm { .. }
| ExprKind::LlvmInlineAsm { .. }
| ExprKind::LogicalOp { .. }
- | ExprKind::Use { .. } => self.in_possible_lhs_union_assign = false,
+ | ExprKind::Use { .. } => {
+ // We don't need to save the old value and restore it
+ // because all the place expressions can't have more
+ // than one child.
+ self.assignment_info = None;
+ }
};
match expr.kind {
ExprKind::Scope { value, lint_level: LintLevel::Explicit(hir_id), region_scope: _ } => {
self.safety_context = closure_visitor.safety_context;
}
ExprKind::Field { lhs, .. } => {
- // assigning to union field is okay for AccessToUnionField
- if let ty::Adt(adt_def, _) = &self.thir[lhs].ty.kind() {
+ let lhs = &self.thir[lhs];
+ if let ty::Adt(adt_def, _) = lhs.ty.kind() {
if adt_def.is_union() {
- if self.in_possible_lhs_union_assign {
- // FIXME: trigger AssignToDroppingUnionField unsafety if needed
+ if let Some((assigned_ty, assignment_span)) = self.assignment_info {
+ // To avoid semver hazard, we only consider `Copy` and `ManuallyDrop` non-dropping.
+ if !(assigned_ty
+ .ty_adt_def()
+ .map_or(false, |adt| adt.is_manually_drop())
+ || assigned_ty
+ .is_copy_modulo_regions(self.tcx.at(expr.span), self.param_env))
+ {
+ self.requires_unsafe(assignment_span, AssignToDroppingUnionField);
+ } else {
+ // write to non-drop union field, safe
+ }
} else {
self.requires_unsafe(expr.span, AccessToUnionField);
}
}
}
ExprKind::Assign { lhs, rhs } | ExprKind::AssignOp { lhs, rhs, .. } => {
+ let lhs = &self.thir[lhs];
// First, check whether we are mutating a layout constrained field
let mut visitor = LayoutConstrainedPlaceVisitor::new(self.thir, self.tcx);
- visit::walk_expr(&mut visitor, &self.thir[lhs]);
+ visit::walk_expr(&mut visitor, lhs);
if visitor.found {
self.requires_unsafe(expr.span, MutationOfLayoutConstrainedField);
}
// Second, check for accesses to union fields
// don't have any special handling for AssignOp since it causes a read *and* write to lhs
if matches!(expr.kind, ExprKind::Assign { .. }) {
- // assigning to a union is safe, check here so it doesn't get treated as a read later
- self.in_possible_lhs_union_assign = true;
- visit::walk_expr(self, &self.thir()[lhs]);
- self.in_possible_lhs_union_assign = false;
+ self.assignment_info = Some((lhs.ty, expr.span));
+ visit::walk_expr(self, lhs);
+ self.assignment_info = None;
visit::walk_expr(self, &self.thir()[rhs]);
return; // we have already visited everything by now
}
}
- ExprKind::Borrow { borrow_kind, arg } => match borrow_kind {
- BorrowKind::Shallow | BorrowKind::Shared | BorrowKind::Unique => {
- if !self.thir[arg]
- .ty
- .is_freeze(self.tcx.at(self.thir[arg].span), self.param_env)
- {
- let mut visitor = LayoutConstrainedPlaceVisitor::new(self.thir, self.tcx);
- visit::walk_expr(&mut visitor, expr);
- if visitor.found {
- self.requires_unsafe(expr.span, BorrowOfLayoutConstrainedField);
+ ExprKind::Borrow { borrow_kind, arg } => {
+ let mut visitor = LayoutConstrainedPlaceVisitor::new(self.thir, self.tcx);
+ visit::walk_expr(&mut visitor, expr);
+ if visitor.found {
+ match borrow_kind {
+ BorrowKind::Shallow | BorrowKind::Shared | BorrowKind::Unique
+ if !self.thir[arg]
+ .ty
+ .is_freeze(self.tcx.at(self.thir[arg].span), self.param_env) =>
+ {
+ self.requires_unsafe(expr.span, BorrowOfLayoutConstrainedField)
}
+ BorrowKind::Mut { .. } => {
+ self.requires_unsafe(expr.span, MutationOfLayoutConstrainedField)
+ }
+ BorrowKind::Shallow | BorrowKind::Shared | BorrowKind::Unique => {}
}
}
- BorrowKind::Mut { .. } => {
- let mut visitor = LayoutConstrainedPlaceVisitor::new(self.thir, self.tcx);
- visit::walk_expr(&mut visitor, expr);
- if visitor.found {
- self.requires_unsafe(expr.span, MutationOfLayoutConstrainedField);
- }
- }
- },
+ }
_ => {}
}
visit::walk_expr(self, expr);
UseOfMutableStatic,
UseOfExternStatic,
DerefOfRawPointer,
- #[allow(dead_code)] // FIXME
AssignToDroppingUnionField,
AccessToUnionField,
- #[allow(dead_code)] // FIXME
MutationOfLayoutConstrainedField,
- #[allow(dead_code)] // FIXME
BorrowOfLayoutConstrainedField,
CallToFunctionWith,
}
hir_context: hir_id,
body_unsafety,
body_target_features,
- in_possible_lhs_union_assign: false,
+ assignment_info: None,
in_union_destructure: false,
param_env: tcx.param_env(def.did),
inside_adt: false,
projects / rust.git / blobdiff