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Rollup merge of #78101 - RalfJung:foreign-static, r=oli-obk

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fix static_ptr_ty for foreign statics

Cc https://github.com/rust-lang/rust/issues/74840

This does not fix that issue but fixes a problem in `static_ptr_ty` that we noticed while discussing that issue. I also added and updated a few comments. The one about `internal` locals being ignored does not seem to have been true [even in the commit that introduced it](https://github.com/rust-lang/rust/pull/44700/files#diff-ae2f3c7e2f9744f7ef43e96072b10e98d4e3fe74a3a399a3ad8a810fbe56c520R139).

r? @oli-obk
This commit is contained in:
Yuki Okushi 2020-10-21 13:59:43 +09:00 • committed by GitHub
commit 83f126bedf
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6 changed files with 25 additions and 17 deletions
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9
compiler/rustc_middle/src/mir/mod.rs
View file

@ -821,9 +821,6 @@ pub struct LocalDecl<'tcx> {
/// flag drop flags to avoid triggering this check as they are introduced
/// after typeck.
///
/// Unsafety checking will also ignore dereferences of these locals,
/// so they can be used for raw pointers only used in a desugaring.
///
/// This should be sound because the drop flags are fully algebraic, and
/// therefore don't affect the OIBIT or outlives properties of the
/// generator.
@ -1010,13 +1007,13 @@ impl<'tcx> LocalDecl<'tcx> {
}
/// Returns `Some` if this is a reference to a static item that is used to
/// access that static
/// access that static.
pub fn is_ref_to_static(&self) -> bool {
matches!(self.local_info, Some(box LocalInfo::StaticRef { .. }))
}
/// Returns `Some` if this is a reference to a static item that is used to
/// access that static
/// Returns `Some` if this is a reference to a thread-local static item that is used to
/// access that static.
pub fn is_ref_to_thread_local(&self) -> bool {
match self.local_info {
Some(box LocalInfo::StaticRef { is_thread_local, .. }) => is_thread_local,

8
compiler/rustc_middle/src/mir/tcx.rs
View file

@ -152,10 +152,14 @@ impl<'tcx> Rvalue<'tcx> {
tcx.mk_ty(ty::Array(operand.ty(local_decls, tcx), count))
}
Rvalue::ThreadLocalRef(did) => {
let static_ty = tcx.type_of(did);
if tcx.is_mutable_static(did) {
tcx.mk_mut_ptr(tcx.type_of(did))
tcx.mk_mut_ptr(static_ty)
} else if tcx.is_foreign_item(did) {
tcx.mk_imm_ptr(static_ty)
} else {
tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.type_of(did))
// FIXME: These things don't *really* have 'static lifetime.
tcx.mk_imm_ref(tcx.lifetimes.re_static, static_ty)
}
}
Rvalue::Ref(reg, bk, ref place) => {

4
compiler/rustc_middle/src/ty/util.rs
View file

@ -529,8 +529,12 @@ impl<'tcx> TyCtxt<'tcx> {
// Make sure that any constants in the static's type are evaluated.
let static_ty = self.normalize_erasing_regions(ty::ParamEnv::empty(), self.type_of(def_id));
// Make sure that accesses to unsafe statics end up using raw pointers.
// For thread-locals, this needs to be kept in sync with `Rvalue::ty`.
if self.is_mutable_static(def_id) {
self.mk_mut_ptr(static_ty)
} else if self.is_foreign_item(def_id) {
self.mk_imm_ptr(static_ty)
} else {
self.mk_imm_ref(self.lifetimes.re_erased, static_ty)
}