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Make unused_allocation
lint against Box::new
too
#104363
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r? @nagisa (rustbot has picked a reviewer for you, use r? to override) |
Hey! It looks like you've submitted a new PR for the library teams! If this PR contains changes to any Examples of
|
@rustbot label -T-libs |
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This unfortunately may need a full FCP at least. While the lint itself is not new, the way it is expanded in scope is going to be going from affecting approximately no users to affecting a large majority of them. If there is I guess one thing we can do before an FCP is run a crater. Could you make this lint a error-by-default so we can kick-off a run and see how much of the ecosystem actually explodes? |
The FCP makes sense, that's a significant change to the lint. However I don't really see the reasoning for running the crater. Using |
@nagisa making an FCP sounds reasonable, can you start it? I don't think running crater makes sense as this won't affect dependencies (cap-lints) and projects want breakage on new warnings if they deny warnings so it's fine. |
I'll label the issue to signal that an FCP is needed (hope I'm using the correct incantation). @rustbot label -S-waiting-on-review S-waiting-on-team needs-fcp |
The changes of this PR are documented in the main post. TLDR: we're making a lint smarter, which means it will trigger on code it previously did not trigger on. @rfcbot merge |
Team member @oli-obk has proposed to merge this. The next step is review by the rest of the tagged team members:
No concerns currently listed. Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up! See this document for info about what commands tagged team members can give me. |
I have done the same thing that this PR is doing in #97774 , but eventually closed it, due to the lint suggesting But in retrospect, this seems like a papercut to me: the lint does not emit any rustfixable suggestions or anything. I think this PR is good because it makes the lint less specific to box syntax, so 👍 from me. |
ping @nikomatsakis @pnkfelix @wesleywiser :) |
assert!(a.downcast::<Box<Test>>().is_err()); | ||
assert!(b.downcast::<Box<i32>>().is_err()); | ||
assert!(a.downcast::<Box<i32>>().is_err()); | ||
assert!(b.downcast::<Box<Test>>().is_err()); |
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It took me a fair amount of squinting before I realized why this change was an improvement to the test. :)
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@Nilstrieb I'm not sure what you mean... I've already done this... |
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r=me after the FCP is complete and the test is changed
The final comment period, with a disposition to merge, as per the review above, is now complete. As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed. This will be merged soon. |
@bors r=Nilstrieb |
…rieb Make `unused_allocation` lint against `Box::new` too Previously it only linted against `box` syntax, which likely won't ever be stabilized, which is pretty useless. Even now I'm not sure if it's a meaningful lint, but it's at least something 🤷 This means that code like the following will be linted against: ```rust Box::new([1, 2, 3]).len(); f(&Box::new(1)); // where f : &i32 -> () ``` The lint works by checking if a `Box::new` (or `box`) expression has an a borrow adjustment, meaning that the code that first stores the box in a variable won't be linted against: ```rust let boxed = Box::new([1, 2, 3]); // no lint boxed.len(); ```
…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#104363 (Make `unused_allocation` lint against `Box::new` too) - rust-lang#106633 (Stabilize `nonzero_min_max`) - rust-lang#106844 (allow negative numeric literals in `concat!`) - rust-lang#108071 (Implement goal caching with the new solver) - rust-lang#108542 (Force parentheses around `match` expression in binary expression) - rust-lang#108690 (Place size limits on query keys and values) - rust-lang#108708 (Prevent overflow through Arc::downgrade) - rust-lang#108739 (Prevent the `start_bx` basic block in codegen from having two `Builder`s at the same time) - rust-lang#108806 (Querify register_tools and post-expansion early lints) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
Always set `RUSTC_BOOTSTRAP` with `x doc` Fixes rust-lang#100060 Note that there is still a warning - the `unused_allocation` lint does not fire in stage 0, but that's just a matter of waiting for rust-lang#104363 to land in beta
Pkgsrc changes: * Adjust patches and cargo checksums to new versions. * Adjust to not cross-build to 8.0, due to LLVM using c++17, so adjust USE_LANGUAGES. Upstream changes: Version 1.70.0 (2023-06-01) ========================== Language -------- - [Relax ordering rules for `asm!` operands] (rust-lang/rust#105798) - [Properly allow macro expanded `format_args` invocations to uses captures] (rust-lang/rust#106505) - [Lint ambiguous glob re-exports] (rust-lang/rust#107880) - [Perform const and unsafe checking for expressions in `let _ = expr` position.] (rust-lang/rust#102256) Compiler -------- - [Extend -Cdebuginfo with new options and named aliases] (rust-lang/rust#109808) This provides a smaller version of debuginfo for cases that only need line number information (`-Cdebuginfo=line-tables-only`), which may eventually become the default for `-Cdebuginfo=1`. - [Make `unused_allocation` lint against `Box::new` too] (rust-lang/rust#104363) - [Detect uninhabited types early in const eval] (rust-lang/rust#109435) - [Switch to LLD as default linker for {arm,thumb}v4t-none-eabi] (rust-lang/rust#109721) - [Add tier 3 target `loongarch64-unknown-linux-gnu`] (rust-lang/rust#96971) - [Add tier 3 target for `i586-pc-nto-qnx700` (QNX Neutrino RTOS, version 7.0)] (rust-lang/rust#109173), - [Insert alignment checks for pointer dereferences as debug assertions] (rust-lang/rust#98112) This catches undefined behavior at runtime, and may cause existing code to fail. Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Document NonZeroXxx layout guarantees] (rust-lang/rust#94786) - [Windows: make `Command` prefer non-verbatim paths] (rust-lang/rust#96391) - [Implement Default for some alloc/core iterators] (rust-lang/rust#99929) - [Fix handling of trailing bare CR in str::lines] (rust-lang/rust#100311) - [allow negative numeric literals in `concat!`] (rust-lang/rust#106844) - [Add documentation about the memory layout of `Cell`] (rust-lang/rust#106921) - [Use `partial_cmp` to implement tuple `lt`/`le`/`ge`/`gt`] (rust-lang/rust#108157) - [Stabilize `atomic_as_ptr`] (rust-lang/rust#108419) - [Stabilize `nonnull_slice_from_raw_parts`] (rust-lang/rust#97506) - [Partial stabilization of `once_cell`] (rust-lang/rust#105587) - [Stabilize `nonzero_min_max`] (rust-lang/rust#106633) - [Flatten/inline format_args!() and (string and int) literal arguments into format_args!()] (rust-lang/rust#106824) - [Stabilize movbe target feature] (rust-lang/rust#107711) - [don't splice from files into pipes in io::copy] (rust-lang/rust#108283) - [Add a builtin unstable `FnPtr` trait that is implemented for all function pointers] (rust-lang/rust#108080) This extends `Debug`, `Pointer`, `Hash`, `PartialEq`, `Eq`, `PartialOrd`, and `Ord` implementations for function pointers with all ABIs. Stabilized APIs --------------- - [`NonZero*::MIN/MAX`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroI8.html#associatedconstant.MIN) - [`BinaryHeap::retain`] (https://doc.rust-lang.org/stable/std/collections/struct.BinaryHeap.html#method.retain) - [`Default for std::collections::binary_heap::IntoIter`] (https://doc.rust-lang.org/stable/std/collections/binary_heap/struct.IntoIter.html) - [`Default for std::collections::btree_map::{IntoIter, Iter, IterMut}`] (https://doc.rust-lang.org/stable/std/collections/btree_map/struct.IntoIter.html) - [`Default for std::collections::btree_map::{IntoKeys, Keys}`] (https://doc.rust-lang.org/stable/std/collections/btree_map/struct.IntoKeys.html) - [`Default for std::collections::btree_map::{IntoValues, Values}`] (https://doc.rust-lang.org/stable/std/collections/btree_map/struct.IntoKeys.html) - [`Default for std::collections::btree_map::Range`] (https://doc.rust-lang.org/stable/std/collections/btree_map/struct.Range.html) - [`Default for std::collections::btree_set::{IntoIter, Iter}`] (https://doc.rust-lang.org/stable/std/collections/btree_set/struct.IntoIter.html) - [`Default for std::collections::btree_set::Range`] (https://doc.rust-lang.org/stable/std/collections/btree_set/struct.Range.html) - [`Default for std::collections::linked_list::{IntoIter, Iter, IterMut}`] (https://doc.rust-lang.org/stable/alloc/collections/linked_list/struct.IntoIter.html) - [`Default for std::vec::IntoIter`] (https://doc.rust-lang.org/stable/alloc/vec/struct.IntoIter.html#impl-Default-for-IntoIter%3CT,+A%3E) - [`Default for std::iter::Chain`] (https://doc.rust-lang.org/stable/std/iter/struct.Chain.html) - [`Default for std::iter::Cloned`] (https://doc.rust-lang.org/stable/std/iter/struct.Cloned.html) - [`Default for std::iter::Copied`] (https://doc.rust-lang.org/stable/std/iter/struct.Copied.html) - [`Default for std::iter::Enumerate`] (https://doc.rust-lang.org/stable/std/iter/struct.Enumerate.html) - [`Default for std::iter::Flatten`] (https://doc.rust-lang.org/stable/std/iter/struct.Flatten.html) - [`Default for std::iter::Fuse`] (https://doc.rust-lang.org/stable/std/iter/struct.Fuse.html) - [`Default for std::iter::Rev`] (https://doc.rust-lang.org/stable/std/iter/struct.Rev.html) - [`Default for std::slice::Iter`] (https://doc.rust-lang.org/stable/std/slice/struct.Iter.html) - [`Default for std::slice::IterMut`] (https://doc.rust-lang.org/stable/std/slice/struct.IterMut.html) - [`Rc::into_inner`] (https://doc.rust-lang.org/stable/alloc/rc/struct.Rc.html#method.into_inner) - [`Arc::into_inner`] (https://doc.rust-lang.org/stable/alloc/sync/struct.Arc.html#method.into_inner) - [`std::cell::OnceCell`] (https://doc.rust-lang.org/stable/std/cell/struct.OnceCell.html) - [`Option::is_some_and`] (https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.is_some_and) - [`NonNull::slice_from_raw_parts`] (https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.slice_from_raw_parts) - [`Result::is_ok_and`] (https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.is_ok_and) - [`Result::is_err_and`] (https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.is_err_and) - [`std::sync::atomic::Atomic*::as_ptr`] (https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicU8.html#method.as_ptr) - [`std::io::IsTerminal`] (https://doc.rust-lang.org/stable/std/io/trait.IsTerminal.html) - [`std::os::linux::net::SocketAddrExt`] (https://doc.rust-lang.org/stable/std/os/linux/net/trait.SocketAddrExt.html) - [`std::os::unix::net::UnixDatagram::bind_addr`] (https://doc.rust-lang.org/stable/std/os/unix/net/struct.UnixDatagram.html#method.bind_addr) - [`std::os::unix::net::UnixDatagram::connect_addr`] (https://doc.rust-lang.org/stable/std/os/unix/net/struct.UnixDatagram.html#method.connect_addr) - [`std::os::unix::net::UnixDatagram::send_to_addr`] (https://doc.rust-lang.org/stable/std/os/unix/net/struct.UnixDatagram.html#method.send_to_addr) - [`std::os::unix::net::UnixListener::bind_addr`] (https://doc.rust-lang.org/stable/std/os/unix/net/struct.UnixListener.html#method.bind_addr) - [`std::path::Path::as_mut_os_str`] (https://doc.rust-lang.org/stable/std/path/struct.Path.html#method.as_mut_os_str) - [`std::sync::OnceLock`] (https://doc.rust-lang.org/stable/std/sync/struct.OnceLock.html) Cargo ----- - [Add `CARGO_PKG_README`] (rust-lang/cargo#11645) - [Make `sparse` the default protocol for crates.io] (rust-lang/cargo#11791) - [Accurately show status when downgrading dependencies] (rust-lang/cargo#11839) - [Use registry.default for login/logout] (rust-lang/cargo#11949) - [Stabilize `cargo logout`] (rust-lang/cargo#11950) Misc ---- - [Stabilize rustdoc `--test-run-directory`] (rust-lang/rust#103682) Compatibility Notes ------------------- - [Prevent stable `libtest` from supporting `-Zunstable-options`] (rust-lang/rust#109044) - [Perform const and unsafe checking for expressions in `let _ = expr` position.] (rust-lang/rust#102256) - [WebAssembly targets enable `sign-ext` and `mutable-globals` features in codegen] (rust-lang/rust#109807) This may cause incompatibility with older execution environments. - [Insert alignment checks for pointer dereferences as debug assertions] (rust-lang/rust#98112) This catches undefined behavior at runtime, and may cause existing code to fail. 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. - [Upgrade to LLVM 16] (rust-lang/rust#109474) - [Use SipHash-1-3 instead of SipHash-2-4 for StableHasher] (rust-lang/rust#107925)
Pkgsrc changes: * Adjust patches and cargo checksums to new versions. * Add support for NetBSD/riscv64. Upstream changes: Version 1.70.0 (2023-06-01) ========================== Language -------- - [Relax ordering rules for `asm!` operands] (rust-lang/rust#105798) - [Properly allow macro expanded `format_args` invocations to uses captures] (rust-lang/rust#106505) - [Lint ambiguous glob re-exports] (rust-lang/rust#107880) - [Perform const and unsafe checking for expressions in `let _ = expr` position.] (rust-lang/rust#102256) Compiler -------- - [Extend -Cdebuginfo with new options and named aliases] (rust-lang/rust#109808) This provides a smaller version of debuginfo for cases that only need line number information (`-Cdebuginfo=line-tables-only`), which may eventually become the default for `-Cdebuginfo=1`. - [Make `unused_allocation` lint against `Box::new` too] (rust-lang/rust#104363) - [Detect uninhabited types early in const eval] (rust-lang/rust#109435) - [Switch to LLD as default linker for {arm,thumb}v4t-none-eabi] (rust-lang/rust#109721) - [Add tier 3 target `loongarch64-unknown-linux-gnu`] (rust-lang/rust#96971) - [Add tier 3 target for `i586-pc-nto-qnx700`(QNX Neutrino RTOS, version 7.0)] (rust-lang/rust#109173), - [Insert alignment checks for pointer dereferences as debug assertions] (rust-lang/rust#98112) This catches undefined behavior at runtime, and may cause existing code to fail. Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Document NonZeroXxx layout guarantees] (rust-lang/rust#94786) - [Windows: make `Command` prefer non-verbatim paths] (rust-lang/rust#96391) - [Implement Default for some alloc/core iterators] (rust-lang/rust#99929) - [Fix handling of trailing bare CR in str::lines] (rust-lang/rust#100311) - [allow negative numeric literals in `concat!`] (rust-lang/rust#106844) - [Add documentation about the memory layout of `Cell`] (rust-lang/rust#106921) - [Use `partial_cmp` to implement tuple `lt`/`le`/`ge`/`gt`] (rust-lang/rust#108157) - [Stabilize `atomic_as_ptr`] (rust-lang/rust#108419) - [Stabilize `nonnull_slice_from_raw_parts`] (rust-lang/rust#97506) - [Partial stabilization of `once_cell`] (rust-lang/rust#105587) - [Stabilize `nonzero_min_max`] (rust-lang/rust#106633) - [Flatten/inline format_args!() and (string and int) literal arguments into format_args!()] (rust-lang/rust#106824) - [Stabilize movbe target feature] (rust-lang/rust#107711) - [don't splice from files into pipes in io::copy] (rust-lang/rust#108283) - [Add a builtin unstable `FnPtr` trait that is implemented for all function pointers] (rust-lang/rust#108080) This extends `Debug`, `Pointer`, `Hash`, `PartialEq`, `Eq`, `PartialOrd`, and `Ord` implementations for function pointers with all ABIs. Stabilized APIs --------------- - [`NonZero*::MIN/MAX`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroI8.html#associatedconstant.MIN) - [`BinaryHeap::retain`] (https://doc.rust-lang.org/stable/std/collections/struct.BinaryHeap.html#method.retain) - [`Default for std::collections::binary_heap::IntoIter`] (https://doc.rust-lang.org/stable/std/collections/binary_heap/struct.IntoIter.html) - [`Default for std::collections::btree_map::{IntoIter, Iter, IterMut}`] (https://doc.rust-lang.org/stable/std/collections/btree_map/struct.IntoIter.html) - [`Default for std::collections::btree_map::{IntoKeys, Keys}`] (https://doc.rust-lang.org/stable/std/collections/btree_map/struct.IntoKeys.html) - [`Default for std::collections::btree_map::{IntoValues, Values}`] (https://doc.rust-lang.org/stable/std/collections/btree_map/struct.IntoKeys.html) - [`Default for std::collections::btree_map::Range`] (https://doc.rust-lang.org/stable/std/collections/btree_map/struct.Range.html) - [`Default for std::collections::btree_set::{IntoIter, Iter}`] (https://doc.rust-lang.org/stable/std/collections/btree_set/struct.IntoIter.html) - [`Default for std::collections::btree_set::Range`] (https://doc.rust-lang.org/stable/std/collections/btree_set/struct.Range.html) - [`Default for std::collections::linked_list::{IntoIter, Iter, IterMut}`] (https://doc.rust-lang.org/stable/alloc/collections/linked_list/struct.IntoIter.html) - [`Default for std::vec::IntoIter`] (https://doc.rust-lang.org/stable/alloc/vec/struct.IntoIter.html#impl-Default-for-IntoIter%3CT,+A%3E) - [`Default for std::iter::Chain`] (https://doc.rust-lang.org/stable/std/iter/struct.Chain.html) - [`Default for std::iter::Cloned`] (https://doc.rust-lang.org/stable/std/iter/struct.Cloned.html) - [`Default for std::iter::Copied`] (https://doc.rust-lang.org/stable/std/iter/struct.Copied.html) - [`Default for std::iter::Enumerate`] (https://doc.rust-lang.org/stable/std/iter/struct.Enumerate.html) - [`Default for std::iter::Flatten`] (https://doc.rust-lang.org/stable/std/iter/struct.Flatten.html) - [`Default for std::iter::Fuse`] (https://doc.rust-lang.org/stable/std/iter/struct.Fuse.html) - [`Default for std::iter::Rev`] (https://doc.rust-lang.org/stable/std/iter/struct.Rev.html) - [`Default for std::slice::Iter`] (https://doc.rust-lang.org/stable/std/slice/struct.Iter.html) - [`Default for std::slice::IterMut`] (https://doc.rust-lang.org/stable/std/slice/struct.IterMut.html) - [`Rc::into_inner`] (https://doc.rust-lang.org/stable/alloc/rc/struct.Rc.html#method.into_inner) - [`Arc::into_inner`] (https://doc.rust-lang.org/stable/alloc/sync/struct.Arc.html#method.into_inner) - [`std::cell::OnceCell`] (https://doc.rust-lang.org/stable/std/cell/struct.OnceCell.html) - [`Option::is_some_and`] (https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.is_some_and) - [`NonNull::slice_from_raw_parts`] (https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.slice_from_raw_parts) - [`Result::is_ok_and`] (https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.is_ok_and) - [`Result::is_err_and`] (https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.is_err_and) - [`std::sync::atomic::Atomic*::as_ptr`] (https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicU8.html#method.as_ptr) - [`std::io::IsTerminal`] (https://doc.rust-lang.org/stable/std/io/trait.IsTerminal.html) - [`std::os::linux::net::SocketAddrExt`] (https://doc.rust-lang.org/stable/std/os/linux/net/trait.SocketAddrExt.html) - [`std::os::unix::net::UnixDatagram::bind_addr`] (https://doc.rust-lang.org/stable/std/os/unix/net/struct.UnixDatagram.html#method.bind_addr) - [`std::os::unix::net::UnixDatagram::connect_addr`] (https://doc.rust-lang.org/stable/std/os/unix/net/struct.UnixDatagram.html#method.connect_addr) - [`std::os::unix::net::UnixDatagram::send_to_addr`] (https://doc.rust-lang.org/stable/std/os/unix/net/struct.UnixDatagram.html#method.send_to_addr) - [`std::os::unix::net::UnixListener::bind_addr`] (https://doc.rust-lang.org/stable/std/os/unix/net/struct.UnixListener.html#method.bind_addr) - [`std::path::Path::as_mut_os_str`] (https://doc.rust-lang.org/stable/std/path/struct.Path.html#method.as_mut_os_str) - [`std::sync::OnceLock`] (https://doc.rust-lang.org/stable/std/sync/struct.OnceLock.html) Cargo ----- - [Add `CARGO_PKG_README`] (rust-lang/cargo#11645) - [Make `sparse` the default protocol for crates.io] (rust-lang/cargo#11791) - [Accurately show status when downgrading dependencies] (rust-lang/cargo#11839) - [Use registry.default for login/logout] (rust-lang/cargo#11949) - [Stabilize `cargo logout`] (rust-lang/cargo#11950) Misc ---- - [Stabilize rustdoc `--test-run-directory`] (rust-lang/rust#103682) Compatibility Notes ------------------- - [Prevent stable `libtest` from supporting `-Zunstable-options`] (rust-lang/rust#109044) - [Perform const and unsafe checking for expressions in `let _ = expr` position.] (rust-lang/rust#102256) - [WebAssembly targets enable `sign-ext` and `mutable-globals` features in codegen] (rust-lang/rust#109807) This may cause incompatibility with older execution environments. - [Insert alignment checks for pointer dereferences as debug assertions] (rust-lang/rust#98112) This catches undefined behavior at runtime, and may cause existing code to fail. 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. - [Upgrade to LLVM 16] (rust-lang/rust#109474) - [Use SipHash-1-3 instead of SipHash-2-4 for StableHasher] (rust-lang/rust#107925)
Previously it only linted against
box
syntax, which likely won't ever be stabilized, which is pretty useless. Even now I'm not sure if it's a meaningful lint, but it's at least something 🤷This means that code like the following will be linted against:
The lint works by checking if a
Box::new
(orbox
) expression has an a borrow adjustment, meaning that the code that first stores the box in a variable won't be linted against: