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Retag argument to drop_in_place unconditionally

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This commit is contained in:
Jakob Degen 2022-12-06 01:18:24 -08:00
parent 102040ce76
commit c359ab0b5d
6 changed files with 34 additions and 47 deletions
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3
compiler/rustc_mir_transform/src/shim.rs
View file

@ -174,7 +174,6 @@ fn build_drop_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>)
let mut body =
new_body(source, blocks, local_decls_for_sig(&sig, span), sig.inputs().len(), span);
if ty.is_some() {
// The first argument (index 0), but add 1 for the return value.
let mut dropee_ptr = Place::from(Local::new(1 + 0));
if tcx.sess.opts.unstable_opts.mir_emit_retag {
@ -203,6 +202,8 @@ fn build_drop_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>)
.push(Statement { source_info, kind: s });
}
}
if ty.is_some() {
let patch = {
let param_env = tcx.param_env_reveal_all_normalized(def_id);
let mut elaborator =

2
src/tools/miri/tests/fail/stacked_borrows/drop_in_place_protector.rs
View file

@ -10,7 +10,7 @@ impl Drop for HasDrop {
fn drop(&mut self) {
unsafe {
let _val = *P;
//~^ ERROR: /not granting access .* because that would remove .* which is protected/
//~^ ERROR: /not granting access .* because that would remove .* which is strongly protected/
}
}
}

4
src/tools/miri/tests/fail/stacked_borrows/drop_in_place_protector.stderr
View file

@ -1,8 +1,8 @@
error: Undefined Behavior: not granting access to tag <TAG> because that would remove [Unique for <TAG>] which is protected because it is an argument of call ID
error: Undefined Behavior: not granting access to tag <TAG> because that would remove [Unique for <TAG>] which is strongly protected because it is an argument of call ID
--> $DIR/drop_in_place_protector.rs:LL:CC
|
LL | let _val = *P;
| ^^ not granting access to tag <TAG> because that would remove [Unique for <TAG>] which is protected because it is an argument of call ID
| ^^ not granting access to tag <TAG> because that would remove [Unique for <TAG>] which is strongly protected because it is an argument of call ID
|
= help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental
= help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information

9
src/tools/miri/tests/fail/stacked_borrows/drop_in_place_retag.rs
View file

@ -3,16 +3,9 @@
//@error-pattern: /retag .* for Unique permission .* only grants SharedReadOnly permission/
#[repr(transparent)]
struct HasDrop;
impl Drop for HasDrop {
fn drop(&mut self) {}
}
fn main() {
unsafe {
let x = (0u8, HasDrop);
let x = 0u8;
let x = core::ptr::addr_of!(x);
core::ptr::drop_in_place(x.cast_mut());
}

2
src/tools/miri/tests/fail/stacked_borrows/drop_in_place_retag.stderr
View file

@ -15,7 +15,7 @@ help: <TAG> was created by a SharedReadOnly retag at offsets [0x0..0x1]
LL | let x = core::ptr::addr_of!(x);
| ^^^^^^^^^^^^^^^^^^^^^^
= note: BACKTRACE:
= note: inside `std::ptr::drop_in_place::<(u8, HasDrop)> - shim(Some((u8, HasDrop)))` at RUSTLIB/core/src/ptr/mod.rs:LL:CC
= note: inside `std::ptr::drop_in_place::<u8> - shim(None)` at RUSTLIB/core/src/ptr/mod.rs:LL:CC
note: inside `main` at $DIR/drop_in_place_retag.rs:LL:CC
--> $DIR/drop_in_place_retag.rs:LL:CC
|

7
src/tools/miri/tests/pass/drop_in_place_null.rs
View file

@ -1,7 +0,0 @@
// Make sure that dropping types with no drop glue is DB even for invalid pointers.
fn main() {
unsafe {
core::ptr::drop_in_place::<u8>(core::ptr::null_mut());
}
}