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Delete current polymorphization implementation #810
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This issue is not meant to be used for technical discussion. There is a Zulip stream for that. Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed. Concerns or objections to the proposal should be discussed on Zulip and formally registered here by adding a comment with the following syntax:
Concerns can be lifted with:
See documentation at https://forge.rust-lang.org cc @rust-lang/compiler |
I'm reasonably confident that a new polymorphization implementation should be rewritten from scratch. From the codegen-adjacent type-system side, removing polymorphism would remove some hacks that I've been wanting to get rid of. @rustbot second |
@rustbot label -final-comment-period +major-change-accepted |
…compiler-errors Remove polymorphization This PR removes the flag `-Zpolymorphize` and all the infrastructure in the compiler that exists only to support it, per rust-lang/compiler-team#810.
…errors Remove polymorphization This PR removes the flag `-Zpolymorphize` and all the infrastructure in the compiler that exists only to support it, per rust-lang/compiler-team#810.
Pkgsrc changes relative to rust184: * patch reorganization to deal with new version of upstream vendored crates, checksum updates. Version 1.85.0 (2025-02-20) ========================== Language -------- - [The 2024 Edition is now stable.] (rust-lang/rust#133349) See [the edition guide] (https://doc.rust-lang.org/nightly/edition-guide/rust-2024/index.html) for more details. - [Stabilize async closures] (rust-lang/rust#132706) See [RFC 3668] (https://rust-lang.github.io/rfcs/3668-async-closures.html) for more details. - [Stabilize `#[diagnostic::do_not_recommend]`] (rust-lang/rust#132056) - [Add `unpredictable_function_pointer_comparisons` lint to warn against function pointer comparisons] (rust-lang/rust#118833) - [Lint on combining `#[no_mangle]` and `#[export_name]` attributes.] (rust-lang/rust#131558) Compiler -------- - [The unstable flag `-Zpolymorphize` has been removed] (rust-lang/rust#133883), see rust-lang/compiler-team#810 for some background. Platform Support ---------------- - [Promote `powerpc64le-unknown-linux-musl` to tier 2 with host tools] (rust-lang/rust#133801) Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Panics in the standard library now have a leading `library/` in their path] (rust-lang/rust#132390) - [`std::env::home_dir()` on Windows now ignores the non-standard `$HOME` environment variable] (rust-lang/rust#132515) It will be un-deprecated in a subsequent release. - [Add `AsyncFn*` to the prelude in all editions.] (rust-lang/rust#132611) Stabilized APIs --------------- - [`BuildHasherDefault::new`] (https://doc.rust-lang.org/stable/std/hash/struct.BuildHasherDefault.html#method.new) - [`ptr::fn_addr_eq`] (https://doc.rust-lang.org/std/ptr/fn.fn_addr_eq.html) - [`io::ErrorKind::QuotaExceeded`] (https://doc.rust-lang.org/stable/std/io/enum.ErrorKind.html#variant.QuotaExceeded) - [`io::ErrorKind::CrossesDevices`] (https://doc.rust-lang.org/stable/std/io/enum.ErrorKind.html#variant.CrossesDevices) - [`{float}::midpoint`] (https://doc.rust-lang.org/core/primitive.f32.html#method.midpoint) - [Unsigned `{integer}::midpoint`] (https://doc.rust-lang.org/std/primitive.u64.html#method.midpoint) - [`NonZeroU*::midpoint`] (https://doc.rust-lang.org/std/num/type.NonZeroU32.html#method.midpoint) - [impl `std::iter::Extend` for tuples with arity 1 through 12] (https://doc.rust-lang.org/stable/std/iter/trait.Extend.html#impl-Extend%3C(A,)%3E-for-(EA,)) - [`FromIterator<(A, ...)>` for tuples with arity 1 through 12] (https://doc.rust-lang.org/stable/std/iter/trait.FromIterator.html#impl-FromIterator%3C(EA,)%3E-for-(A,)) - [`std::task::Waker::noop`] (https://doc.rust-lang.org/stable/std/task/struct.Waker.html#method.noop) These APIs are now stable in const contexts: - [`mem::size_of_val`] (https://doc.rust-lang.org/stable/std/mem/fn.size_of_val.html) - [`mem::align_of_val`] (https://doc.rust-lang.org/stable/std/mem/fn.align_of_val.html) - [`Layout::for_value`] (https://doc.rust-lang.org/stable/std/alloc/struct.Layout.html#method.for_value) - [`Layout::align_to`] (https://doc.rust-lang.org/stable/std/alloc/struct.Layout.html#method.align_to) - [`Layout::pad_to_align`] (https://doc.rust-lang.org/stable/std/alloc/struct.Layout.html#method.pad_to_align) - [`Layout::extend`] (https://doc.rust-lang.org/stable/std/alloc/struct.Layout.html#method.extend) - [`Layout::array`] (https://doc.rust-lang.org/stable/std/alloc/struct.Layout.html#method.array) - [`std::mem::swap`] (https://doc.rust-lang.org/stable/std/mem/fn.swap.html) - [`std::ptr::swap`] (https://doc.rust-lang.org/stable/std/ptr/fn.swap.html) - [`NonNull::new`] (https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.new) - [`HashMap::with_hasher`] (https://doc.rust-lang.org/stable/std/collections/struct.HashMap.html#method.with_hasher) - [`HashSet::with_hasher`] (https://doc.rust-lang.org/stable/std/collections/struct.HashSet.html#method.with_hasher) - [`BuildHasherDefault::new`] (https://doc.rust-lang.org/stable/std/hash/struct.BuildHasherDefault.html#method.new) - [`<float>::recip`] (https://doc.rust-lang.org/stable/std/primitive.f32.html#method.recip) - [`<float>::to_degrees`] (https://doc.rust-lang.org/stable/std/primitive.f32.html#method.to_degrees) - [`<float>::to_radians`] (https://doc.rust-lang.org/stable/std/primitive.f32.html#method.to_radians) - [`<float>::max`] (https://doc.rust-lang.org/stable/std/primitive.f32.html#method.max) - [`<float>::min`] (https://doc.rust-lang.org/stable/std/primitive.f32.html#method.min) - [`<float>::clamp`] (https://doc.rust-lang.org/stable/std/primitive.f32.html#method.clamp) - [`<float>::abs`] (https://doc.rust-lang.org/stable/std/primitive.f32.html#method.abs) - [`<float>::signum`] (https://doc.rust-lang.org/stable/std/primitive.f32.html#method.signum) - [`<float>::copysign`] (https://doc.rust-lang.org/stable/std/primitive.f32.html#method.copysign) - [`MaybeUninit::write`] (https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.write) Cargo ----- - [Add future-incompatibility warning against keywords in cfgs and add raw-idents] (rust-lang/cargo#14671) - [Stabilize higher precedence trailing flags] (rust-lang/cargo#14900) - [Pass `CARGO_CFG_FEATURE` to build scripts] (rust-lang/cargo#14902) Rustdoc ----- - [Doc comment on impl blocks shows the first line, even when the impl block is collapsed] (rust-lang/rust#132155) Compatibility Notes ------------------- - [`rustc` no longer treats the `test` cfg as a well known check-cfg] (rust-lang/rust#131729), instead it is up to the build systems and users of `--check-cfg`[^check-cfg] to set it as a well known cfg using `--check-cfg=cfg(test)`. This is done to enable build systems like Cargo to set it conditionally, as not all source files are suitable for unit tests. [Cargo (for now) unconditionally sets the `test` cfg as a well known cfg] (rust-lang/cargo#14963). [^check-cfg]: https://doc.rust-lang.org/nightly/rustc/check-cfg.html - [Disable potentially incorrect type inference if there are trivial and non-trivial where-clauses] (rust-lang/rust#132325) - `std::env::home_dir()` has been deprecated for years, because it can give surprising results in some Windows configurations if the `HOME` environment variable is set (which is not the normal configuration on Windows). We had previously avoided changing its behavior, out of concern for compatibility with code depending on this non-standard configuration. Given how long this function has been deprecated, we're now fixing its behavior as a bugfix. A subsequent release will remove the deprecation for this function. - [Make `core::ffi::c_char` signedness more closely match that of the platform-default `char`] (rust-lang/rust#132975) This changed `c_char` from an `i8` to `u8` or vice versa on many Tier 2 and 3 targets (mostly Arm and RISC-V embedded targets). The new definition may result in compilation failures but fixes compatibility issues with C. The `libc` crate matches this change as of its 0.2.169 release. - [When compiling a nested `macro_rules` macro from an external crate, the content of the inner `macro_rules` is now built with the edition of the external crate, not the local crate.] (rust-lang/rust#133274) - [Increase `sparcv9-sun-solaris` and `x86_64-pc-solaris` Solaris baseline to 11.4.] (rust-lang/rust#133293) - [Show `abi_unsupported_vector_types` lint in future breakage reports] (rust-lang/rust#133374) - [Error if multiple super-trait instantiations of `dyn Trait` need associated types to be specified but only one is provided] (rust-lang/rust#133392) - [Change `powerpc64-ibm-aix` default `codemodel` to large] (rust-lang/rust#133811) 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. - [Build `x86_64-unknown-linux-gnu` with LTO for C/C++ code (e.g., `jemalloc`)] (rust-lang/rust#134690)
This MR contains the following updates: | Package | Update | Change | |---|---|---| | [rust](/~https://github.com/rust-lang/rust) | minor | `1.84.1` -> `1.85.0` | 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> ### [`v1.85.0`](/~https://github.com/rust-lang/rust/blob/HEAD/RELEASES.md#Version-1850-2025-02-20) [Compare Source](rust-lang/rust@1.84.1...1.85.0) \========================== <a id="1.85.0-Language"></a> ## Language - [The 2024 Edition is now stable.](rust-lang/rust#133349) See [the edition guide](https://doc.rust-lang.org/nightly/edition-guide/rust-2024/index.html) for more details. - [Stabilize async closures](rust-lang/rust#132706) See [RFC 3668](https://rust-lang.github.io/rfcs/3668-async-closures.html) for more details. - [Stabilize `#[diagnostic::do_not_recommend]`](rust-lang/rust#132056) - [Add `unpredictable_function_pointer_comparisons` lint to warn against function pointer comparisons](rust-lang/rust#118833) - [Lint on combining `#[no_mangle]` and `#[export_name]` attributes.](rust-lang/rust#131558) <a id="1.85.0-Compiler"></a> ## Compiler - [The unstable flag `-Zpolymorphize` has been removed](rust-lang/rust#133883), see rust-lang/compiler-team#810 for some background. <a id="1.85.0-Platform-Support"></a> ## Platform Support - [Promote `powerpc64le-unknown-linux-musl` to tier 2 with host tools](rust-lang/rust#133801) Refer to Rust's \[platform support page]\[platform-support-doc] for more information on Rust's tiered platform support. <a id="1.85.0-Libraries"></a> ## Libraries - [Panics in the standard library now have a leading `library/` in their path](rust-lang/rust#132390) - [`std::env::home_dir()` on Windows now ignores the non-standard `$HOME` environment variable](rust-lang/rust#132515) It will be un-deprecated in a subsequent release. - [Add `AsyncFn*` to the prelude in all editions.](rust-lang/rust#132611) <a id="1.85.0-Stabilized-APIs"></a> ## Stabilized APIs - [`BuildHasherDefault::new`](https://doc.rust-lang.org/stable/std/hash/struct.BuildHasherDefault.html#method.new) - [`ptr::fn_addr_eq`](https://doc.rust-lang.org/std/ptr/fn.fn_addr_eq.html) - [`io::ErrorKind::QuotaExceeded`](https://doc.rust-lang.org/stable/std/io/enum.ErrorKind.html#variant.QuotaExceeded) - [`io::ErrorKind::CrossesDevices`](https://doc.rust-lang.org/stable/std/io/enum.ErrorKind.html#variant.CrossesDevices) - [`{float}::midpoint`](https://doc.rust-lang.org/core/primitive.f32.html#method.midpoint) - [Unsigned `{integer}::midpoint`](https://doc.rust-lang.org/std/primitive.u64.html#method.midpoint) - [`NonZeroU*::midpoint`](https://doc.rust-lang.org/std/num/type.NonZeroU32.html#method.midpoint) - [impl `std::iter::Extend` for tuples with arity 1 through 12](https://doc.rust-lang.org/stable/std/iter/trait.Extend.html#impl-Extend%3C\(A,\)%3E-for-\(EA,\)) - [`FromIterator<(A, ...)>` for tuples with arity 1 through 12](https://doc.rust-lang.org/stable/std/iter/trait.FromIterator.html#impl-FromIterator%3C\(EA,\)%3E-for-\(A,\)) - [`std::task::Waker::noop`](https://doc.rust-lang.org/stable/std/task/struct.Waker.html#method.noop) These APIs are now stable in const contexts: - [`mem::size_of_val`](https://doc.rust-lang.org/stable/std/mem/fn.size_of_val.html) - [`mem::align_of_val`](https://doc.rust-lang.org/stable/std/mem/fn.align_of_val.html) - [`Layout::for_value`](https://doc.rust-lang.org/stable/std/alloc/struct.Layout.html#method.for_value) - [`Layout::align_to`](https://doc.rust-lang.org/stable/std/alloc/struct.Layout.html#method.align_to) - [`Layout::pad_to_align`](https://doc.rust-lang.org/stable/std/alloc/struct.Layout.html#method.pad_to_align) - [`Layout::extend`](https://doc.rust-lang.org/stable/std/alloc/struct.Layout.html#method.extend) - [`Layout::array`](https://doc.rust-lang.org/stable/std/alloc/struct.Layout.html#method.array) - [`std::mem::swap`](https://doc.rust-lang.org/stable/std/mem/fn.swap.html) - [`std::ptr::swap`](https://doc.rust-lang.org/stable/std/ptr/fn.swap.html) - [`NonNull::new`](https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.new) - [`HashMap::with_hasher`](https://doc.rust-lang.org/stable/std/collections/struct.HashMap.html#method.with_hasher) - [`HashSet::with_hasher`](https://doc.rust-lang.org/stable/std/collections/struct.HashSet.html#method.with_hasher) - [`BuildHasherDefault::new`](https://doc.rust-lang.org/stable/std/hash/struct.BuildHasherDefault.html#method.new) - [`<float>::recip`](https://doc.rust-lang.org/stable/std/primitive.f32.html#method.recip) - [`<float>::to_degrees`](https://doc.rust-lang.org/stable/std/primitive.f32.html#method.to_degrees) - [`<float>::to_radians`](https://doc.rust-lang.org/stable/std/primitive.f32.html#method.to_radians) - [`<float>::max`](https://doc.rust-lang.org/stable/std/primitive.f32.html#method.max) - [`<float>::min`](https://doc.rust-lang.org/stable/std/primitive.f32.html#method.min) - [`<float>::clamp`](https://doc.rust-lang.org/stable/std/primitive.f32.html#method.clamp) - [`<float>::abs`](https://doc.rust-lang.org/stable/std/primitive.f32.html#method.abs) - [`<float>::signum`](https://doc.rust-lang.org/stable/std/primitive.f32.html#method.signum) - [`<float>::copysign`](https://doc.rust-lang.org/stable/std/primitive.f32.html#method.copysign) - [`MaybeUninit::write`](https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.write) <a id="1.85.0-Cargo"></a> ## Cargo - [Add future-incompatibility warning against keywords in cfgs and add raw-idents](rust-lang/cargo#14671) - [Stabilize higher precedence trailing flags](rust-lang/cargo#14900) - [Pass `CARGO_CFG_FEATURE` to build scripts](rust-lang/cargo#14902) <a id="1.85.0-Rustdoc"></a> ## Rustdoc - [Doc comment on impl blocks shows the first line, even when the impl block is collapsed](rust-lang/rust#132155) <a id="1.85.0-Compatibility-Notes"></a> ## Compatibility Notes - [`rustc` no longer treats the `test` cfg as a well known check-cfg](rust-lang/rust#131729), instead it is up to the build systems and users of `--check-cfg`\[^check-cfg] to set it as a well known cfg using `--check-cfg=cfg(test)`. This is done to enable build systems like Cargo to set it conditionally, as not all source files are suitable for unit tests. [Cargo (for now) unconditionally sets the `test` cfg as a well known cfg](rust-lang/cargo#14963). \[^check-cfg]: https://doc.rust-lang.org/nightly/rustc/check-cfg.html - [Disable potentially incorrect type inference if there are trivial and non-trivial where-clauses](rust-lang/rust#132325) - `std::env::home_dir()` has been deprecated for years, because it can give surprising results in some Windows configurations if the `HOME` environment variable is set (which is not the normal configuration on Windows). We had previously avoided changing its behavior, out of concern for compatibility with code depending on this non-standard configuration. Given how long this function has been deprecated, we're now fixing its behavior as a bugfix. A subsequent release will remove the deprecation for this function. - [Make `core::ffi::c_char` signedness more closely match that of the platform-default `char`](rust-lang/rust#132975) This changed `c_char` from an `i8` to `u8` or vice versa on many Tier 2 and 3 targets (mostly Arm and RISC-V embedded targets). The new definition may result in compilation failures but fixes compatibility issues with C. The `libc` crate matches this change as of its 0.2.169 release. - [When compiling a nested `macro_rules` macro from an external crate, the content of the inner `macro_rules` is now built with the edition of the external crate, not the local crate.](rust-lang/rust#133274) - [Increase `sparcv9-sun-solaris` and `x86_64-pc-solaris` Solaris baseline to 11.4.](rust-lang/rust#133293) - [Show `abi_unsupported_vector_types` lint in future breakage reports](rust-lang/rust#133374) - [Error if multiple super-trait instantiations of `dyn Trait` need associated types to be specified but only one is provided](rust-lang/rust#133392) - [Change `powerpc64-ibm-aix` default `codemodel` to large](rust-lang/rust#133811) <a id="1.85.0-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. - [Build `x86_64-unknown-linux-gnu` with LTO for C/C++ code (e.g., `jemalloc`)](rust-lang/rust#134690) </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. --- - [ ] <!-- rebase-check -->If you want to rebase/retry this MR, check this box --- This MR has been generated by [Renovate Bot](/~https://github.com/renovatebot/renovate). <!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzOS4xODAuMyIsInVwZGF0ZWRJblZlciI6IjM5LjE4MC4zIiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6WyJSZW5vdmF0ZSBCb3QiXX0=-->
Proposal
I am writing this because I keep tripping over the polymorphization implementation while working on post-mono MIR optimizations. I want there to be a point in the compiler where entire MIR bodies are fully monomorphized and then they stay monomorphized. The current polymorphization implementation breaks that mental model, in at least two ways:
fn monomorphize
and uses it to monomorphize individual consts, operands, etc.TypingEnv::fully_monomorphized
even though this is after monomorphization. /~https://github.com/rust-lang/rust/blob/b19329a37cedf2027517ae22c87cf201f93d776e/compiler/rustc_ty_utils/src/abi.rs#L48-L63So there's this rake, and I keep stepping on it, and it's quite annoying.
I've done a GitHub code search for the flag and I cannot find any actual users: /~https://github.com/search?type=code&q=-Zpolymorphize+NOT+repo%3Arust-lang%2Frust++NOT+repo%3Amatthiaskrgr%2Ficemaker+NOT+repo%3Amatthiaskrgr%2Fglacier+NOT+repo%3Amatthiaskrgr%2Fglacier2+NOT+repo%3Arust-lang%2Fzulip_archive+NOT+path%3A%C2%B7tests%2Fui%2F*+NOT+path%3Atests%2Fui%2F*%2F*+NOT+path%3Atests%2Fui%2F*%2F*%2F*+NOT+path%3A%C2%B7src%2Ftest%2Fui%2F*+NOT+path%3Asrc%2Ftest%2Fui%2F*%2F*+NOT+path%3Asrc%2Ftest%2Fui%2F*%2F*%2F*+NOT+repo%3Adavidtwco%2Fzulip_archive+NOT+path%3Atests%2Fcrashes%2F*.rs&p=1
It doesn't make a whole lot of sense to be spending maintenance effort on a feature that may have users we can't see, but they are so few that none are public on GitHub.
There are a few more details about the current state and history in the feature's tracking issue, including a link to a sketch of a redesign: rust-lang/rust#124962
Mentors or Reviewers
If you have a reviewer or mentor in mind for this work, mention them
here. You can put your own name here if you are planning to mentor the
work.
Process
The main points of the Major Change Process are as follows:
@rustbot second
.-C flag
, then full team check-off is required.@rfcbot fcp merge
on either the MCP or the PR.You can read more about Major Change Proposals on forge.
Comments
This issue is not meant to be used for technical discussion. There is a Zulip stream for that. Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed.
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