unstably constify ptr::drop_in_place

[Qelxiros]

Tracking issue: #109342

[rustbot]

r? @ibraheemdev

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[rust-log-analyzer]

The job x86_64-gnu-miri failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

tests/fail/tree_borrows/reserved/int-protected-write.rs ... ok
tests/fail/tree_borrows/reserved/cell-protected-write.rs ... ok

FAILED TEST: tests/fail/stacked_borrows/drop_in_place_retag.rs
command: MIRI_ENV_VAR_TEST="0" MIRI_TEMP="/tmp/miri-uitest-fFvC7F" RUST_BACKTRACE="1" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/miri" "--error-format=json" "--sysroot=/checkout/obj/build/x86_64-unknown-linux-gnu/miri-sysroot" "-Dwarnings" "-Dunused" "-Ainternal_features" "-Zui-testing" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/tmp/miri_ui/0/tests/fail/stacked_borrows" "tests/fail/stacked_borrows/drop_in_place_retag.rs" "--edition" "2021"

error: actual output differed from expected
Execute `./miri test --bless` to update `tests/fail/stacked_borrows/drop_in_place_retag.stderr` to the actual output
--- tests/fail/stacked_borrows/drop_in_place_retag.stderr
+++ <stderr output>
 error: Undefined Behavior: trying to retag from <TAG> for Unique permission at ALLOC[0x0], but that tag only grants SharedReadOnly permission for this location
   --> RUSTLIB/core/src/ptr/mod.rs:LL:CC
    |
-LL | pub unsafe fn drop_in_place<T: PointeeSized>(to_drop: *mut T) {
+LL | pub const unsafe fn drop_in_place<T: PointeeSized>(to_drop: *mut T) {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this error occurs as part of retag at ALLOC[0x0..0x1]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this error occurs as part of retag at ALLOC[0x0..0x1]
    |
    = help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental
... 17 lines skipped ...
 error: aborting due to 1 previous error
 

Full unnormalized output:
error: Undefined Behavior: trying to retag from <189> for Unique permission at alloc81[0x0], but that tag only grants SharedReadOnly permission for this location
##[error]  --> /checkout/library/core/src/ptr/mod.rs:805:1
   |
LL | pub const unsafe fn drop_in_place<T: PointeeSized>(to_drop: *mut T) {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this error occurs as part of retag at alloc81[0x0..0x1]
   |
   = 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
help: <189> was created by a SharedReadOnly retag at offsets [0x0..0x1]
  --> tests/fail/stacked_borrows/drop_in_place_retag.rs:9:17
   |
LL |         let x = core::ptr::addr_of!(x);
   |                 ^^^^^^^^^^^^^^^^^^^^^^
   = note: BACKTRACE (of the first span):
   = note: inside `std::ptr::drop_in_place::<u8> - shim(None)` at /checkout/library/core/src/ptr/mod.rs:805:1: 805:68
note: inside `main`
  --> tests/fail/stacked_borrows/drop_in_place_retag.rs:10:9
   |
LL |         core::ptr::drop_in_place(x.cast_mut());
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
---



full stderr:
error: Undefined Behavior: trying to retag from <189> for Unique permission at alloc81[0x0], but that tag only grants SharedReadOnly permission for this location
##[error]  --> /checkout/library/core/src/ptr/mod.rs:805:1
   |
LL | pub const unsafe fn drop_in_place<T: PointeeSized>(to_drop: *mut T) {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this error occurs as part of retag at alloc81[0x0..0x1]
   |
   = 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
help: <189> was created by a SharedReadOnly retag at offsets [0x0..0x1]
  --> tests/fail/stacked_borrows/drop_in_place_retag.rs:9:17
   |
LL |         let x = core::ptr::addr_of!(x);
   |                 ^^^^^^^^^^^^^^^^^^^^^^
   = note: BACKTRACE (of the first span):
   = note: inside `std::ptr::drop_in_place::<u8> - shim(None)` at /checkout/library/core/src/ptr/mod.rs:805:1: 805:68
note: inside `main`
  --> tests/fail/stacked_borrows/drop_in_place_retag.rs:10:9
   |
LL |         core::ptr::drop_in_place(x.cast_mut());
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
---



FAILED TEST: tests/fail/unaligned_pointers/drop_in_place.rs
command: MIRI_ENV_VAR_TEST="0" MIRI_TEMP="/tmp/miri-uitest-fFvC7F" RUST_BACKTRACE="1" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/miri" "--error-format=json" "--sysroot=/checkout/obj/build/x86_64-unknown-linux-gnu/miri-sysroot" "-Dwarnings" "-Dunused" "-Ainternal_features" "-Zui-testing" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/tmp/miri_ui/0/tests/fail/unaligned_pointers" "tests/fail/unaligned_pointers/drop_in_place.rs" "-Cdebug-assertions=no" "--edition" "2021"

error: actual output differed from expected
Execute `./miri test --bless` to update `tests/fail/unaligned_pointers/drop_in_place.stderr` to the actual output
--- tests/fail/unaligned_pointers/drop_in_place.stderr
+++ <stderr output>
 error: Undefined Behavior: constructing invalid value: encountered an unaligned reference (required ALIGN byte alignment but found ALIGN)
   --> RUSTLIB/core/src/ptr/mod.rs:LL:CC
    |
-LL | pub unsafe fn drop_in_place<T: PointeeSized>(to_drop: *mut T) {
+LL | pub const unsafe fn drop_in_place<T: PointeeSized>(to_drop: *mut T) {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
... 11 lines skipped ...
 error: aborting due to 1 previous error
 

Full unnormalized output:
error: Undefined Behavior: constructing invalid value: encountered an unaligned reference (required 2 byte alignment but found 1)
##[error]  --> /checkout/library/core/src/ptr/mod.rs:805:1
   |
LL | pub const unsafe fn drop_in_place<T: PointeeSized>(to_drop: *mut T) {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
   |
   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
   = note: BACKTRACE:
   = note: inside `std::ptr::drop_in_place::<PartialDrop> - shim(Some(PartialDrop))` at /checkout/library/core/src/ptr/mod.rs:805:1: 805:68
note: inside `main`
  --> tests/fail/unaligned_pointers/drop_in_place.rs:25:9
   |
LL |         core::ptr::drop_in_place(p);
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
---
full stderr:
error: Undefined Behavior: constructing invalid value: encountered an unaligned reference (required 2 byte alignment but found 1)
##[error]  --> /checkout/library/core/src/ptr/mod.rs:805:1
   |
LL | pub const unsafe fn drop_in_place<T: PointeeSized>(to_drop: *mut T) {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
   |
   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
   = note: BACKTRACE:
   = note: inside `std::ptr::drop_in_place::<PartialDrop> - shim(Some(PartialDrop))` at /checkout/library/core/src/ptr/mod.rs:805:1: 805:68
note: inside `main`
  --> tests/fail/unaligned_pointers/drop_in_place.rs:25:9
   |
LL |         core::ptr::drop_in_place(p);
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
---
Location:
   /cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ui_test-0.30.2/src/lib.rs:365

  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ BACKTRACE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   1: <color_eyre[3c4c3f14ce67c862]::config::EyreHook>::into_eyre_hook::{closure#0}<unknown>
      at <unknown source file>:<unknown line>
   2: eyre[27939c37cd2918af]::private::format_err<unknown>
      at <unknown source file>:<unknown line>
   3: ui_test[998f70e21c9d4f21]::run_tests_generic::<ui_test[998f70e21c9d4f21]::default_file_filter, ui[b420cc9bae658438]::run_tests::{closure#1}, alloc[38aebdd1529a32f0]::boxed::Box<dyn ui_test[998f70e21c9d4f21]::status_emitter::StatusEmitter>><unknown>
      at <unknown source file>:<unknown line>
   4: ui[b420cc9bae658438]::ui<unknown>
      at <unknown source file>:<unknown line>
   5: ui[b420cc9bae658438]::main<unknown>
      at <unknown source file>:<unknown line>
   6: std[6aac5b2b65832922]::sys::backtrace::__rust_begin_short_backtrace::<fn() -> core[6d3892dd075386a0]::result::Result<(), eyre[27939c37cd2918af]::Report>, core[6d3892dd075386a0]::result::Result<(), eyre[27939c37cd2918af]::Report>><unknown>
      at <unknown source file>:<unknown line>
   7: std[6aac5b2b65832922]::rt::lang_start::<core[6d3892dd075386a0]::result::Result<(), eyre[27939c37cd2918af]::Report>>::{closure#0}<unknown>
      at <unknown source file>:<unknown line>
   8: std[6aac5b2b65832922]::rt::lang_start_internal<unknown>
      at <unknown source file>:<unknown line>
   9: main<unknown>
      at <unknown source file>:<unknown line>
  10: __libc_start_main<unknown>
      at <unknown source file>:<unknown line>
  11: _start<unknown>
      at <unknown source file>:<unknown line>

Run with COLORBT_SHOW_HIDDEN=1 environment variable to disable frame filtering.
Run with RUST_BACKTRACE=full to include source snippets.
error: test failed, to rerun pass `--test ui`

Caused by:
  process didn't exit successfully: `/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/ui-de637b1a885c82e4` (exit status: 1)
Bootstrap failed while executing `test --stage 2 src/tools/miri src/tools/miri/cargo-miri`
Command `/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo test --target x86_64-unknown-linux-gnu -Zbinary-dep-depinfo -j 4 -Zroot-dir=/checkout --locked --color always --release --manifest-path /checkout/src/tools/miri/Cargo.toml -- [workdir=/checkout]` failed with exit code 1
Created at: src/bootstrap/src/core/build_steps/tool.rs:189:21
Executed at: src/bootstrap/src/core/build_steps/test.rs:644:19

Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:40:20
  local time: Thu Aug 21 21:58:42 UTC 2025
  network time: Thu, 21 Aug 2025 21:58:42 GMT
##[error]Process completed with exit code 1.
Post job cleanup.

[clarfonthey]

Poking in since I'd like this for #145939 and you haven't fixed the tests yet. Would be willing to take over this if you aren't working on it right now.

[Qelxiros]

I'm getting weird errors when I try to run miri, so you're welcome to pick this up.

[Qelxiros]

superseded by #146187