Allow constraining opaque types during subtyping in the trait system #125447

oli-obk · 2024-05-23T10:31:22Z

Previous attempt: #123979

Sometimes we don't immediately perform subtyping, but instead register a subtyping obligation and solve that obligation when its inference variables become resolved. Unlike immediate subtyping, we currently do not allow registering hidden types for opaque types. This PR also allows that.

tests/ui/type-alias-impl-trait/lazy_subtyping_of_opaques.rs

tests/ui/impl-trait/lazy_subtyping_of_opaques.rs

lcnr · 2024-05-24T13:49:26Z

A minimized test:

fn foo() -> impl Default {
    let x = Default::default();
    // add `Subtype(?x, ?y)` obligation
    let y = x;

    // Make a tuple `(?x, ?y)` and equate it with `(impl Default, u32)`.
    // For us to try and prove a `Subtype(impl Default, u32)` obligation,
    // we have to instantiate both `?x` and `?y` without any
    // `select_where_possible` calls inbetween.
    let tup = &mut (x, y);
    let assign_tup = &mut (foo(), 1u32);
    tup = assign_tup;
    1u32
}

fn main() {}

I think this change is clearly desirable, even if it did no go through an FCP. From what I can tell it also doesn't block any other work, as I want us to convert all places to use DefineOpaqueTypes::Yes before stabilizing ATPIT. I would like us to FCP this.

While I think it would have been fine to FCP merge this without first reverting this PR, we would only have 1 week to go through the FCP to make it in time for its stabilization. Given that we're missing some existing uncertainty wrt the impact of this change, please revert #123979 and remerge it after a types FCP.

compiler-errors · 2024-06-18T15:32:50Z

@bors r+

bors · 2024-06-18T15:32:53Z

📌 Commit 1e9cd07 has been approved by compiler-errors

It is now in the queue for this repository.

…-errors Allow constraining opaque types during subtyping in the trait system Previous attempt: rust-lang#123979 Sometimes we don't immediately perform subtyping, but instead register a subtyping obligation and solve that obligation when its inference variables become resolved. Unlike immediate subtyping, we currently do not allow registering hidden types for opaque types. This PR also allows that.

jieyouxu · 2024-06-19T00:48:33Z

UI tests might need rebless #126653 (comment)
@bors r-

oli-obk · 2024-06-19T08:30:30Z

@bors r=compiler-errors

bors · 2024-06-19T08:30:32Z

📌 Commit ba4510e has been approved by compiler-errors

It is now in the queue for this repository.

Rollup of 6 pull requests Successful merges: - rust-lang#125447 (Allow constraining opaque types during subtyping in the trait system) - rust-lang#125766 (MCDC Coverage: instrument last boolean RHS operands from condition coverage) - rust-lang#125880 (Remove `src/tools/rust-demangler`) - rust-lang#126154 (StorageLive: refresh storage (instead of UB) when local is already live) - rust-lang#126572 (override user defined channel when using precompiled rustc) - rust-lang#126662 (Unconditionally warn on usage of `wasm32-wasi`) r? `@ghost` `@rustbot` modify labels: rollup

bors · 2024-06-19T13:34:50Z

⌛ Testing commit ba4510e with merge 3186d17...

Rollup merge of rust-lang#125447 - oli-obk:eq_opaque_pred, r=compiler-errors Allow constraining opaque types during subtyping in the trait system Previous attempt: rust-lang#123979 Sometimes we don't immediately perform subtyping, but instead register a subtyping obligation and solve that obligation when its inference variables become resolved. Unlike immediate subtyping, we currently do not allow registering hidden types for opaque types. This PR also allows that.

fmease · 2024-06-19T13:36:28Z

It's already merged, bors. What the hell?
@bors r-

Edit: We currently have three full-build pending PRs, omg.

fmease · 2024-06-19T13:39:10Z

@bors retry r-

This MR contains the following updates: | Package | Update | Change | |---|---|---| | [rust](https://github.com/rust-lang/rust) | minor | `1.80.1` -> `1.81.0` | MR created with the help of [el-capitano/tools/renovate-bot](https://gitlab.com/el-capitano/tools/renovate-bot). **Proposed changes to behavior should be submitted there as MRs.** --- ### Release Notes <details> <summary>rust-lang/rust (rust)</summary> ### [`v1.81.0`](https://github.com/rust-lang/rust/blob/HEAD/RELEASES.md#Version-1810-2024-09-05) [Compare Source](rust-lang/rust@1.80.1...1.81.0) \========================== <a id="1.81.0-Language"></a> ## Language - [Abort on uncaught panics in `extern "C"` functions.](rust-lang/rust#116088) - [Fix ambiguous cases of multiple `&` in elided self lifetimes.](rust-lang/rust#117967) - [Stabilize `#[expect]` for lints (RFC 2383),](rust-lang/rust#120924) like `#[allow]` with a warning if the lint is *not* fulfilled. - [Change method resolution to constrain hidden types instead of rejecting method candidates.](rust-lang/rust#123962) - [Bump `elided_lifetimes_in_associated_constant` to deny.](rust-lang/rust#124211) - [`offset_from`: always allow pointers to point to the same address.](rust-lang/rust#124921) - [Allow constraining opaque types during subtyping in the trait system.](rust-lang/rust#125447) - [Allow constraining opaque types during various unsizing casts.](rust-lang/rust#125610) - [Deny keyword lifetimes pre-expansion.](rust-lang/rust#126762) <a id="1.81.0-Compiler"></a> ## Compiler - [Make casts of pointers to trait objects stricter.](rust-lang/rust#120248) - [Check alias args for well-formedness even if they have escaping bound vars.](rust-lang/rust#123737) - [Deprecate no-op codegen option `-Cinline-threshold=...`.](rust-lang/rust#124712) - [Re-implement a type-size based limit.](rust-lang/rust#125507) - [Properly account for alignment in `transmute` size checks.](rust-lang/rust#125740) - [Remove the `box_pointers` lint.](rust-lang/rust#126018) - [Ensure the interpreter checks bool/char for validity when they are used in a cast.](rust-lang/rust#126265) - [Improve coverage instrumentation for functions containing nested items.](rust-lang/rust#127199) - Target changes: - [Add Tier 3 `no_std` Xtensa targets:](rust-lang/rust#125141) `xtensa-esp32-none-elf`, `xtensa-esp32s2-none-elf`, `xtensa-esp32s3-none-elf` - [Add Tier 3 `std` Xtensa targets:](rust-lang/rust#126380) `xtensa-esp32-espidf`, `xtensa-esp32s2-espidf`, `xtensa-esp32s3-espidf` - [Add Tier 3 i686 Redox OS target:](rust-lang/rust#126192) `i686-unknown-redox` - [Promote `arm64ec-pc-windows-msvc` to Tier 2.](rust-lang/rust#126039) - [Promote `loongarch64-unknown-linux-musl` to Tier 2 with host tools.](rust-lang/rust#126298) - [Enable full tools and profiler for LoongArch Linux targets.](rust-lang/rust#127078) - [Unconditionally warn on usage of `wasm32-wasi`.](rust-lang/rust#126662) (see compatibility note below) - Refer to Rust's \[platform support page]\[platform-support-doc] for more information on Rust's tiered platform support. <a id="1.81.0-Libraries"></a> ## Libraries - [Split core's `PanicInfo` and std's `PanicInfo`.](rust-lang/rust#115974) (see compatibility note below) - [Generalize `{Rc,Arc}::make_mut()` to unsized types.](rust-lang/rust#116113) - [Replace sort implementations with stable `driftsort` and unstable `ipnsort`.](rust-lang/rust#124032) All `slice::sort*` and `slice::select_nth*` methods are expected to see significant performance improvements. See the [research project](https://github.com/Voultapher/sort-research-rs) for more details. - [Document behavior of `create_dir_all` with respect to empty paths.](rust-lang/rust#125112) - [Fix interleaved output in the default panic hook when multiple threads panic simultaneously.](rust-lang/rust#127397) <a id="1.81.0-Stabilized-APIs"></a> ## Stabilized APIs - [`core::error`](https://doc.rust-lang.org/stable/core/error/index.html) - [`hint::assert_unchecked`](https://doc.rust-lang.org/stable/core/hint/fn.assert_unchecked.html) - [`fs::exists`](https://doc.rust-lang.org/stable/std/fs/fn.exists.html) - [`AtomicBool::fetch_not`](https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicBool.html#method.fetch_not) - [`Duration::abs_diff`](https://doc.rust-lang.org/stable/core/time/struct.Duration.html#method.abs_diff) - [`IoSlice::advance`](https://doc.rust-lang.org/stable/std/io/struct.IoSlice.html#method.advance) - [`IoSlice::advance_slices`](https://doc.rust-lang.org/stable/std/io/struct.IoSlice.html#method.advance_slices) - [`IoSliceMut::advance`](https://doc.rust-lang.org/stable/std/io/struct.IoSliceMut.html#method.advance) - [`IoSliceMut::advance_slices`](https://doc.rust-lang.org/stable/std/io/struct.IoSliceMut.html#method.advance_slices) - [`PanicHookInfo`](https://doc.rust-lang.org/stable/std/panic/struct.PanicHookInfo.html) - [`PanicInfo::message`](https://doc.rust-lang.org/stable/core/panic/struct.PanicInfo.html#method.message) - [`PanicMessage`](https://doc.rust-lang.org/stable/core/panic/struct.PanicMessage.html) These APIs are now stable in const contexts: - [`char::from_u32_unchecked`](https://doc.rust-lang.org/stable/core/char/fn.from_u32\_unchecked.html) (function) - [`char::from_u32_unchecked`](https://doc.rust-lang.org/stable/core/primitive.char.html#method.from_u32\_unchecked) (method) - [`CStr::count_bytes`](https://doc.rust-lang.org/stable/core/ffi/c_str/struct.CStr.html#method.count_bytes) - [`CStr::from_ptr`](https://doc.rust-lang.org/stable/core/ffi/c_str/struct.CStr.html#method.from_ptr) <a id="1.81.0-Cargo"></a> ## Cargo - [Generated `.cargo_vcs_info.json` is always included, even when `--allow-dirty` is passed.](rust-lang/cargo#13960) - [Disallow `package.license-file` and `package.readme` pointing to non-existent files during packaging.](rust-lang/cargo#13921) - [Disallow passing `--release`/`--debug` flag along with the `--profile` flag.](rust-lang/cargo#13971) - [Remove `lib.plugin` key support in `Cargo.toml`. Rust plugin support has been deprecated for four years and was removed in 1.75.0.](rust-lang/cargo#13902) <a id="1.81.0-Compatibility-Notes"></a> ## Compatibility Notes - Usage of the `wasm32-wasi` target will now issue a compiler warning and request users switch to the `wasm32-wasip1` target instead. Both targets are the same, `wasm32-wasi` is only being renamed, and this [change to the WASI target](https://blog.rust-lang.org/2024/04/09/updates-to-rusts-wasi-targets.html) is being done to enable removing `wasm32-wasi` in January 2025. - We have renamed `std::panic::PanicInfo` to `std::panic::PanicHookInfo`. The old name will continue to work as an alias, but will result in a deprecation warning starting in Rust 1.82.0. `core::panic::PanicInfo` will remain unchanged, however, as this is now a *different type*. The reason is that these types have different roles: `std::panic::PanicHookInfo` is the argument to the [panic hook](https://doc.rust-lang.org/stable/std/panic/fn.set_hook.html) in std context (where panics can have an arbitrary payload), while `core::panic::PanicInfo` is the argument to the [`#[panic_handler]`](https://doc.rust-lang.org/nomicon/panic-handler.html) in no_std context (where panics always carry a formatted *message*). Separating these types allows us to add more useful methods to these types, such as `std::panic::PanicHookInfo::payload_as_str()` and `core::panic::PanicInfo::message()`. - The new sort implementations may panic if a type's implementation of [`Ord`](https://doc.rust-lang.org/std/cmp/trait.Ord.html) (or the given comparison function) does not implement a [total order](https://en.wikipedia.org/wiki/Total_order) as the trait requires. `Ord`'s supertraits (`PartialOrd`, `Eq`, and `PartialEq`) must also be consistent. The previous implementations would not "notice" any problem, but the new implementations have a good chance of detecting inconsistencies, throwing a panic rather than returning knowingly unsorted data. - [In very rare cases, a change in the internal evaluation order of the trait solver may result in new fatal overflow errors.](rust-lang/rust#126128) <a id="1.81.0-Internal-Changes"></a> ## Internal Changes These changes do not affect any public interfaces of Rust, but they represent significant improvements to the performance or internals of rustc and related tools. - [Add a Rust-for Linux `auto` CI job to check kernel builds.](rust-lang/rust#125209) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever MR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this MR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this MR, check this box --- This MR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).

Pkgsrc changes: * Adapt patches, apply to new vendored crates where needed. * Back-port rust pull request 130110, "make dist vendoring configurable" * Disable "dist vendoring", otherwise cargo would try to access the network during the build phase. Upstream changes: Version 1.81.0 (2024-09-05) ========================== Language -------- - [Abort on uncaught panics in `extern "C"` functions.] (rust-lang/rust#116088) - [Fix ambiguous cases of multiple `&` in elided self lifetimes.] (rust-lang/rust#117967) - [Stabilize `#[expect]` for lints (RFC 2383),] (rust-lang/rust#120924) like `#[allow]` with a warning if the lint is _not_ fulfilled. - [Change method resolution to constrain hidden types instead of rejecting method candidates.] (rust-lang/rust#123962) - [Bump `elided_lifetimes_in_associated_constant` to deny.] (rust-lang/rust#124211) - [`offset_from`: always allow pointers to point to the same address.] (rust-lang/rust#124921) - [Allow constraining opaque types during subtyping in the trait system.] (rust-lang/rust#125447) - [Allow constraining opaque types during various unsizing casts.] (rust-lang/rust#125610) - [Deny keyword lifetimes pre-expansion.] (rust-lang/rust#126762) Compiler -------- - [Make casts of pointers to trait objects stricter.] (rust-lang/rust#120248) - [Check alias args for well-formedness even if they have escaping bound vars.] (rust-lang/rust#123737) - [Deprecate no-op codegen option `-Cinline-threshold=...`.] (rust-lang/rust#124712) - [Re-implement a type-size based limit.] (rust-lang/rust#125507) - [Properly account for alignment in `transmute` size checks.] (rust-lang/rust#125740) - [Remove the `box_pointers` lint.] (rust-lang/rust#126018) - [Ensure the interpreter checks bool/char for validity when they are used in a cast.] (rust-lang/rust#126265) - [Improve coverage instrumentation for functions containing nested items.] (rust-lang/rust#127199) - Target changes: - [Add Tier 3 `no_std` Xtensa targets:] (rust-lang/rust#125141) `xtensa-esp32-none-elf`, `xtensa-esp32s2-none-elf`, `xtensa-esp32s3-none-elf` - [Add Tier 3 `std` Xtensa targets:] (rust-lang/rust#126380) `xtensa-esp32-espidf`, `xtensa-esp32s2-espidf`, `xtensa-esp32s3-espidf` - [Add Tier 3 i686 Redox OS target:] (rust-lang/rust#126192) `i686-unknown-redox` - [Promote `arm64ec-pc-windows-msvc` to Tier 2.] (rust-lang/rust#126039) - [Promote `wasm32-wasip2` to Tier 2.] (rust-lang/rust#126967) - [Promote `loongarch64-unknown-linux-musl` to Tier 2 with host tools.] (rust-lang/rust#126298) - [Enable full tools and profiler for LoongArch Linux targets.] (rust-lang/rust#127078) - [Unconditionally warn on usage of `wasm32-wasi`.] (rust-lang/rust#126662) (see compatibility note below) - Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Split core's `PanicInfo` and std's `PanicInfo`.] (rust-lang/rust#115974) (see compatibility note below) - [Generalize `{Rc,Arc}::make_mut()` to unsized types.] (rust-lang/rust#116113) - [Replace sort implementations with stable `driftsort` and unstable `ipnsort`.] (rust-lang/rust#124032) All `slice::sort*` and `slice::select_nth*` methods are expected to see significant performance improvements. See the [research project] (https://github.com/Voultapher/sort-research-rs) for more details. - [Document behavior of `create_dir_all` with respect to empty paths.] (rust-lang/rust#125112) - [Fix interleaved output in the default panic hook when multiple threads panic simultaneously.] (rust-lang/rust#127397) - Fix `Command`'s batch files argument escaping not working when file name has trailing whitespace or periods (CVE-2024-43402). Stabilized APIs --------------- - [`core::error`] (https://doc.rust-lang.org/stable/core/error/index.html) - [`hint::assert_unchecked`] (https://doc.rust-lang.org/stable/core/hint/fn.assert_unchecked.html) - [`fs::exists`] (https://doc.rust-lang.org/stable/std/fs/fn.exists.html) - [`AtomicBool::fetch_not`] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicBool.html#method.fetch_not) - [`Duration::abs_diff`] (https://doc.rust-lang.org/stable/core/time/struct.Duration.html#method.abs_diff) - [`IoSlice::advance`] (https://doc.rust-lang.org/stable/std/io/struct.IoSlice.html#method.advance) - [`IoSlice::advance_slices`] (https://doc.rust-lang.org/stable/std/io/struct.IoSlice.html#method.advance_slices) - [`IoSliceMut::advance`] (https://doc.rust-lang.org/stable/std/io/struct.IoSliceMut.html#method.advance) - [`IoSliceMut::advance_slices`] (https://doc.rust-lang.org/stable/std/io/struct.IoSliceMut.html#method.advance_slices) - [`PanicHookInfo`] (https://doc.rust-lang.org/stable/std/panic/struct.PanicHookInfo.html) - [`PanicInfo::message`] (https://doc.rust-lang.org/stable/core/panic/struct.PanicInfo.html#method.message) - [`PanicMessage`] (https://doc.rust-lang.org/stable/core/panic/struct.PanicMessage.html) These APIs are now stable in const contexts: - [`char::from_u32_unchecked`] (https://doc.rust-lang.org/stable/core/char/fn.from_u32_unchecked.html) (function) - [`char::from_u32_unchecked`] (https://doc.rust-lang.org/stable/core/primitive.char.html#method.from_u32_unchecked) (method) - [`CStr::count_bytes`] (https://doc.rust-lang.org/stable/core/ffi/c_str/struct.CStr.html#method.count_bytes) - [`CStr::from_ptr`] (https://doc.rust-lang.org/stable/core/ffi/c_str/struct.CStr.html#method.from_ptr) Cargo ----- - [Generated `.cargo_vcs_info.json` is always included, even when `--allow-dirty` is passed.] (rust-lang/cargo#13960) - [Disallow `package.license-file` and `package.readme` pointing to non-existent files during packaging.] (rust-lang/cargo#13921) - [Disallow passing `--release`/`--debug` flag along with the `--profile` flag.] (rust-lang/cargo#13971) - [Remove `lib.plugin` key support in `Cargo.toml`. Rust plugin support has been deprecated for four years and was removed in 1.75.0.] (rust-lang/cargo#13902) Compatibility Notes ------------------- * Usage of the `wasm32-wasi` target will now issue a compiler warning and request users switch to the `wasm32-wasip1` target instead. Both targets are the same, `wasm32-wasi` is only being renamed, and this [change to the WASI target] (https://blog.rust-lang.org/2024/04/09/updates-to-rusts-wasi-targets.html) is being done to enable removing `wasm32-wasi` in January 2025. * We have renamed `std::panic::PanicInfo` to `std::panic::PanicHookInfo`. The old name will continue to work as an alias, but will result in a deprecation warning starting in Rust 1.82.0. `core::panic::PanicInfo` will remain unchanged, however, as this is now a *different type*. The reason is that these types have different roles: `std::panic::PanicHookInfo` is the argument to the [panic hook](https://doc.rust-lang.org/stable/std/panic/fn.set_hook.html) in std context (where panics can have an arbitrary payload), while `core::panic::PanicInfo` is the argument to the [`#[panic_handler]`](https://doc.rust-lang.org/nomicon/panic-handler.html) in no_std context (where panics always carry a formatted *message*). Separating these types allows us to add more useful methods to these types, such as `std::panic::PanicHookInfo::payload_as_str()` and `core::panic::PanicInfo::message()`. * The new sort implementations may panic if a type's implementation of [`Ord`](https://doc.rust-lang.org/std/cmp/trait.Ord.html) (or the given comparison function) does not implement a [total order](https://en.wikipedia.org/wiki/Total_order) as the trait requires. `Ord`'s supertraits (`PartialOrd`, `Eq`, and `PartialEq`) must also be consistent. The previous implementations would not "notice" any problem, but the new implementations have a good chance of detecting inconsistencies, throwing a panic rather than returning knowingly unsorted data. * [In very rare cases, a change in the internal evaluation order of the trait solver may result in new fatal overflow errors.] (rust-lang/rust#126128) Internal Changes ---------------- These changes do not affect any public interfaces of Rust, but they represent significant improvements to the performance or internals of rustc and related tools. - [Add a Rust-for Linux `auto` CI job to check kernel builds.] (rust-lang/rust#125209)

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