Use type based qualification for unions
Union field access is currently qualified based on the qualification of
a value previously assigned to the union. At the same time, every union
access transmutes the content of the union, which might result in a
different qualification.
For example, consider constants A and B as defined below, under the
current rules neither contains interior mutability, since a value used
in the initial assignment did not contain `UnsafeCell` constructor.
```rust
#![feature(untagged_unions)]
union U { i: u32, c: std::cell::Cell<u32> }
const A: U = U { i: 0 };
const B: std::cell::Cell<u32> = unsafe { U { i: 0 }.c };
```
To avoid the issue, the changes here propose to consider the content of
a union as opaque and use type based qualification for union types.
Fixes#90268.
`@rust-lang/wg-const-eval`
Consider indirect mutation during const qualification dataflow
Previously a local would be qualified if either one of two separate data
flow computations indicated so. First determined if a local could
contain the qualif, but ignored any forms of indirect mutation. Second
determined if a local could be mutably borrowed (and so indirectly
mutated), but which in turn ignored the qualif.
The end result was incorrect because the effect of indirect mutation was
effectivelly ignored in the all but the final stage of computation.
In the new implementation the indirect mutation is directly incorporated
into the qualif data flow. The local variable becomes immediately
qualified once it is mutably borrowed and borrowed place type can
contain the qualif.
In general we will now reject additional programs, program that were
prevously unintentionally accepted.
There are also some cases which are now accepted but were previously
rejected, because previous implementation didn't consider whether
borrowed place could have the qualif under the consideration.
Fixes#90124.
r? `@ecstatic-morse`
Revert "Add rustc lint, warning when iterating over hashmaps"
Fixes perf regressions introduced in https://github.com/rust-lang/rust/pull/90235 by temporarily reverting the relevant PR.
Various cleanups around opaque types
Best reviewed commit by commit.
This PR has no functional changes.
Mostly it's moving logic from an extension trait in rustc_trait_selection to inherent impls on rustc_infer.
Add BorrowSet to public api
This PR adds `BorrowSet` to the public api so that verification tools can obtain the activation and reservation points of two phase borrows without having to redo calculations themselves (and thus potentially differently from rustc).
Turns out we already can obtain `MoveData` thanks to the public `HasMoveData` trait, so constructing a `BorrowSet` should not provide much of an issue. However, I can't speak to the soundness of this approach, is it safe to take an under-approximation of `MoveData`?
r? `@nikomatsakis`
Fixes incorrect handling of ADT's drop requirements
Fixes#90024 and a bunch of duplicates.
The main issue was just that the contract of `NeedsDropTypes::adt_components` was inconsistent; the list of types it might return were the generic parameters themselves or the fields of the ADT, depending on the nature of the drop impl. This meant that the caller could not determine whether a `.subst()` call was still needed on those types; it called `.subst()` in all cases, and this led to ICEs when the returned types were the generic params.
First contribution of more than a few lines, so feedback definitely appreciated.
Union field access is currently qualified based on the qualification of
a value previously assigned to the union. At the same time, every union
access transmutes the content of the union, which might result in a
different qualification.
For example, consider constants A and B as defined below, under the
current rules neither contains interior mutability, since a value used
in the initial assignment did not contain `UnsafeCell` constructor.
```rust
#![feature(untagged_unions)]
union U { i: u32, c: std::cell::Cell<u32> }
const A: U = U { i: 0 };
const B: std::cell::Cell<u32> = unsafe { U { i: 0 }.c };
```
To avoid the issue, the changes here propose to consider the content of
a union as opaque and use type based qualification for union types.
Rollup of 5 pull requests
Successful merges:
- #90239 (Consistent big O notation in map.rs)
- #90267 (fix: inner attribute followed by outer attribute causing ICE)
- #90288 (Add hint for people missing `TryFrom`, `TryInto`, `FromIterator` import pre-2021)
- #90304 (Add regression test for #75961)
- #90344 (Add tracking issue number to const_cstr_unchecked)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Add hint for people missing `TryFrom`, `TryInto`, `FromIterator` import pre-2021
Adds a hint anytime a `TryFrom`, `TryInto`, `FromIterator` import is suggested noting that these traits are automatically imported in Edition 2021.
fix: inner attribute followed by outer attribute causing ICE
Fixes#87936, #88938, and #89971.
This removes the assertion that validates that there are no outer attributes following inner attributes. Where the inner attribute is invalid you get an actual error.
Clean up special function const checks
Mark them as const and `#[rustc_do_not_const_check]` instead of hard-coding them in const-eval checks.
r? `@oli-obk`
`@rustbot` label A-const-eval T-compiler
Add LLVM CFI support to the Rust compiler
This PR adds LLVM Control Flow Integrity (CFI) support to the Rust compiler. It initially provides forward-edge control flow protection for Rust-compiled code only by aggregating function pointers in groups identified by their number of arguments.
Forward-edge control flow protection for C or C++ and Rust -compiled code "mixed binaries" (i.e., for when C or C++ and Rust -compiled code share the same virtual address space) will be provided in later work as part of this project by defining and using compatible type identifiers (see Type metadata in the design document in the tracking issue #89653).
LLVM CFI can be enabled with -Zsanitizer=cfi and requires LTO (i.e., -Clto).
Thank you, `@eddyb` and `@pcc,` for all the help!
Properly check `target_features` not to trigger an assertion
Fixes#89875
I think it should be a condition instead of an assertion to check if it's a register as it's possible that `reg` is a register class.
Also, this isn't related to the issue directly, but `is_target_supported` doesn't check `target_features` attributes. Is there any way to check it on rustc_codegen_llvm?
r? `@Amanieu`
Edit error messages for `rustc_resolve::AmbiguityKind` variants
Edit the language of the ambiguity descriptions for E0659. These strings now appear as notes.
Closes#79717.
Previously a local would be qualified if either one of two separate data
flow computations indicated so. First determined if a local could
contain the qualif, but ignored any forms of indirect mutation. Second
determined if a local could be mutably borrowed (and so indirectly
mutated), but which in turn ignored the qualif.
The end result was incorrect because the effect of indirect mutation was
effectivelly ignored in the all but the final stage of computation.
In the new implementation the indirect mutation is directly incorporated
into the qualif data flow. The local variable becomes immediately
qualified once it is mutably borrowed and borrowed place type can
contain the qualif.
In general we will now reject additional programs, program that were
prevously unintentionally accepted.
There are also some cases which are now accepted but were previously
rejected, because previous implementation didn't consider whether
borrowed place could have the qualif under the consideration.
Emit description of the ambiguity as a note.
Co-authored-by: Noah Lev <camelidcamel@gmail.com>
Co-authored-by: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>
Avoid a branch on key being local for queries that use the same local and extern providers
Currently based on https://github.com/rust-lang/rust/pull/85810 as it slightly conflicts with it. Only the last two commits are new.
This commit adds LLVM Control Flow Integrity (CFI) support to the Rust
compiler. It initially provides forward-edge control flow protection for
Rust-compiled code only by aggregating function pointers in groups
identified by their number of arguments.
Forward-edge control flow protection for C or C++ and Rust -compiled
code "mixed binaries" (i.e., for when C or C++ and Rust -compiled code
share the same virtual address space) will be provided in later work as
part of this project by defining and using compatible type identifiers
(see Type metadata in the design document in the tracking issue #89653).
LLVM CFI can be enabled with -Zsanitizer=cfi and requires LTO (i.e.,
-Clto).
Prevent duplicate caller bounds candidates by exposing default substs in Unevaluated
Fixes https://github.com/rust-lang/rust/issues/89334
The changes introduced in https://github.com/rust-lang/rust/pull/87280 allowed for "duplicate" caller bounds candidates to be assembled that only differed in their default substs having been "exposed" or not and resulted in an ambiguity error during trait selection. To fix this we expose the defaults substs during the creation of the ParamEnv.
r? `@lcnr`
Add -Z no-unique-section-names to reduce ELF header bloat.
This change adds a new compiler flag that can help reduce the size of ELF binaries that contain many functions.
By default, when enabling function sections (which is the default for most targets), the LLVM backend will generate different section names for each function. For example, a function `func` would generate a section called `.text.func`. Normally this is fine because the linker will merge all those sections into a single one in the binary. However, starting with [LLVM 12](https://github.com/llvm/llvm-project/commit/ee5d1a04), the backend will also generate unique section names for exception handling, resulting in thousands of `.gcc_except_table.*` sections ending up in the final binary because some linkers like LLD don't currently merge or strip these EH sections (see discussion [here](https://reviews.llvm.org/D83655)). This can bloat the ELF headers and string table significantly in binaries that contain many functions.
The new option is analogous to Clang's `-fno-unique-section-names`, and instructs LLVM to generate the same `.text` and `.gcc_except_table` section for each function, resulting in a smaller final binary.
The motivation to add this new option was because we have a binary that ended up with so many ELF sections (over 65,000) that it broke some existing ELF tools, which couldn't handle so many sections.
Here's our old binary:
```
$ readelf --sections old.elf | head -1
There are 71746 section headers, starting at offset 0x2a246508:
$ readelf --sections old.elf | grep shstrtab
[71742] .shstrtab STRTAB 0000000000000000 2977204c ad44bb 00 0 0 1
```
That's an 11MB+ string table. Here's the new binary using this option:
```
$ readelf --sections new.elf | head -1
There are 43 section headers, starting at offset 0x29143ca8:
$ readelf --sections new.elf | grep shstrtab
[40] .shstrtab STRTAB 0000000000000000 29143acc 0001db 00 0 0 1
```
The whole binary size went down by over 20MB, which is quite significant.
enable `i8mm` target feature on aarch64 and arm
As in https://github.com/rust-lang/stdarch/issues/1233, `i8mm` needs to be turned on to support the implementation of `vmmla` and `vusmmla`neon instructions in stdarch.
r? ``@Amanieu``
Rollup of 4 pull requests
Successful merges:
- #89889 (Use the "nice E0277 errors"[1] for `!Send` `impl Future` from foreign crate)
- #90127 (Do not mention a reexported item if it's private)
- #90143 (tidy: Remove submodules from edition exception list)
- #90238 (Add alias for guillaume.gomez@huawei.com)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
