bjoernager/rust
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Rollup merge of #105147 - nbdd0121:inline_const_unsafe, r=oli-obk

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Allow unsafe through inline const

Handle similar to closures.

Address https://github.com/rust-lang/rust/pull/104087#issuecomment-1324173328

Note that this PR does not fix the issue for `unsafe { [0; function_requiring_unsafe()] }`. This is fundamentally unfixable for MIR unsafeck IMO.

This PR also does not fix unsafety checking for inline const in pattern position. It actually breaks it, allowing unsafe functions to be used in inline const in pattern position without unsafe blocks. Inline const in pattern position is not visible in MIR so ignored by MIR unsafety checking (currently it is also not checked by borrow checker, which is the reason why it's considered an incomplete feature).

`@rustbot` label: +T-lang +F-inline_const
This commit is contained in:
Matthias Krüger 2022-12-13 19:57:09 +01:00 • committed by GitHub
commit 7357cfbf3d
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GPG key ID: 4AEE18F83AFDEB23
12 changed files with 177 additions and 19 deletions
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7
compiler/rustc_mir_build/src/build/custom/mod.rs
View file

@ -20,6 +20,7 @@
use rustc_ast::Attribute;
use rustc_data_structures::fx::FxHashMap;
use rustc_hir::def_id::DefId;
use rustc_hir::HirId;
use rustc_index::vec::IndexVec;
use rustc_middle::{
mir::*,
@ -33,6 +34,7 @@ mod parse;
pub(super) fn build_custom_mir<'tcx>(
tcx: TyCtxt<'tcx>,
did: DefId,
hir_id: HirId,
thir: &Thir<'tcx>,
expr: ExprId,
params: &IndexVec<ParamId, Param<'tcx>>,
@ -67,7 +69,10 @@ pub(super) fn build_custom_mir<'tcx>(
parent_scope: None,
inlined: None,
inlined_parent_scope: None,
local_data: ClearCrossCrate::Clear,
local_data: ClearCrossCrate::Set(SourceScopeLocalData {
lint_root: hir_id,
safety: Safety::Safe,
}),
});
body.injection_phase = Some(parse_attribute(attr));

1
compiler/rustc_mir_build/src/build/mod.rs
View file

@ -487,6 +487,7 @@ fn construct_fn<'tcx>(
return custom::build_custom_mir(
tcx,
fn_def.did.to_def_id(),
fn_id,
thir,
expr,
arguments,

34
compiler/rustc_mir_build/src/check_unsafety.rs
View file

@ -132,6 +132,18 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
fn unsafe_op_in_unsafe_fn_allowed(&self) -> bool {
self.tcx.lint_level_at_node(UNSAFE_OP_IN_UNSAFE_FN, self.hir_context).0 == Level::Allow
}
/// Handle closures/generators/inline-consts, which is unsafecked with their parent body.
fn visit_inner_body(&mut self, def: ty::WithOptConstParam<LocalDefId>) {
if let Ok((inner_thir, expr)) = self.tcx.thir_body(def) {
let inner_thir = &inner_thir.borrow();
let hir_context = self.tcx.hir().local_def_id_to_hir_id(def.did);
let mut inner_visitor = UnsafetyVisitor { thir: inner_thir, hir_context, ..*self };
inner_visitor.visit_expr(&inner_thir[expr]);
// Unsafe blocks can be used in the inner body, make sure to take it into account
self.safety_context = inner_visitor.safety_context;
}
}
}
// Searches for accesses to layout constrained fields.
@ -408,16 +420,11 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
} else {
ty::WithOptConstParam::unknown(closure_id)
};
let (closure_thir, expr) = self.tcx.thir_body(closure_def).unwrap_or_else(|_| {
(self.tcx.alloc_steal_thir(Thir::new()), ExprId::from_u32(0))
});
let closure_thir = &closure_thir.borrow();
let hir_context = self.tcx.hir().local_def_id_to_hir_id(closure_id);
let mut closure_visitor =
UnsafetyVisitor { thir: closure_thir, hir_context, ..*self };
closure_visitor.visit_expr(&closure_thir[expr]);
// Unsafe blocks can be used in closures, make sure to take it into account
self.safety_context = closure_visitor.safety_context;
self.visit_inner_body(closure_def);
}
ExprKind::ConstBlock { did, substs: _ } => {
let def_id = did.expect_local();
self.visit_inner_body(ty::WithOptConstParam::unknown(def_id));
}
ExprKind::Field { lhs, .. } => {
let lhs = &self.thir[lhs];
@ -612,11 +619,8 @@ pub fn check_unsafety<'tcx>(tcx: TyCtxt<'tcx>, def: ty::WithOptConstParam<LocalD
return;
}
// Closures are handled by their owner, if it has a body
if tcx.is_closure(def.did.to_def_id()) {
let hir = tcx.hir();
let owner = hir.enclosing_body_owner(hir.local_def_id_to_hir_id(def.did));
tcx.ensure().thir_check_unsafety(owner);
// Closures and inline consts are handled by their owner, if it has a body
if tcx.is_typeck_child(def.did.to_def_id()) {
return;
}