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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)
}

3
compiler/rustc_mir/src/transform/check_unsafety.rs
View File

@ -204,6 +204,9 @@ impl<'a, 'tcx> Visitor<'tcx> for UnsafetyChecker<'a, 'tcx> {
if let [] = proj_base {
let decl = &self.body.local_decls[place.local];
if decl.internal {
// If the projection root is an artifical local that we introduced when
// desugaring `static`, give a more specific error message
// (avoid the general "raw pointer" clause below, that would only be confusing).
if let Some(box LocalInfo::StaticRef { def_id, .. }) = decl.local_info {
if self.tcx.is_mutable_static(def_id) {
self.require_unsafe(

10
src/test/mir-opt/const_promotion_extern_static.FOO-promoted[0].ConstProp.after.mir
View File

@ -4,17 +4,17 @@ promoted[0] in FOO: &[&i32; 1] = {
let mut _0: &[&i32; 1]; // return place in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
let mut _1: [&i32; 1]; // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
let mut _2: &i32; // in scope 0 at $DIR/const-promotion-extern-static.rs:13:32: 13:45
let mut _3: &i32; // in scope 0 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
let mut _3: *const i32; // in scope 0 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
bb0: {
_3 = const {alloc2: &i32}; // scope 0 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
_3 = const {alloc2: *const i32}; // scope 0 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
// ty::Const
// + ty: &i32
// + ty: *const i32
// + val: Value(Scalar(alloc2))
// mir::Constant
// + span: $DIR/const-promotion-extern-static.rs:13:42: 13:43
// + literal: Const { ty: &i32, val: Value(Scalar(alloc2)) }
_2 = _3; // scope 0 at $DIR/const-promotion-extern-static.rs:13:41: 13:43
// + literal: Const { ty: *const i32, val: Value(Scalar(alloc2)) }
_2 = &(*_3); // scope 0 at $DIR/const-promotion-extern-static.rs:13:41: 13:43
_1 = [move _2]; // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
_0 = &_1; // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
return; // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46

8
src/test/mir-opt/const_promotion_extern_static.FOO.PromoteTemps.diff
View File

@ -7,7 +7,7 @@
let mut _2: &[&i32; 1]; // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
let _3: [&i32; 1]; // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
let mut _4: &i32; // in scope 0 at $DIR/const-promotion-extern-static.rs:13:32: 13:45
let _5: &i32; // in scope 0 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
let _5: *const i32; // in scope 0 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
+ let mut _6: &[&i32; 1]; // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
scope 1 {
}
@ -18,16 +18,16 @@
- StorageLive(_3); // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
- StorageLive(_4); // scope 0 at $DIR/const-promotion-extern-static.rs:13:32: 13:45
- StorageLive(_5); // scope 1 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
- _5 = const {alloc2: &i32}; // scope 1 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
- _5 = const {alloc2: *const i32}; // scope 1 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
+ _6 = const FOO::promoted[0]; // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
// ty::Const
- // + ty: &i32
- // + ty: *const i32
- // + val: Value(Scalar(alloc2))
+ // + ty: &[&i32; 1]
+ // + val: Unevaluated(WithOptConstParam { did: DefId(0:7 ~ const_promotion_extern_static[317d]::FOO), const_param_did: None }, [], Some(promoted[0]))
// mir::Constant
- // + span: $DIR/const-promotion-extern-static.rs:13:42: 13:43
- // + literal: Const { ty: &i32, val: Value(Scalar(alloc2)) }
- // + literal: Const { ty: *const i32, val: Value(Scalar(alloc2)) }
- _4 = &(*_5); // scope 1 at $DIR/const-promotion-extern-static.rs:13:41: 13:43
- _3 = [move _4]; // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
- _2 = &_3; // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46