coverage: Clarify some parts of coverage counter creation
This is a series of semi-related changes that are trying to make the `counters` module easier to read, understand, and modify.
For example, the existing code happens to avoid ever using the count for a `TerminatorKind::Yield` node as the count for its sole out-edge (since doing so would be incorrect), but doesn't do so explicitly, so seemingly-innocent changes can result in baffling test failures.
This PR also takes the opportunity to simplify some debug-logging code that was making its surrounding code disproportionately hard to read.
There should be no changes to the resulting coverage instrumentation/mappings, as demonstrated by the absence of changes to the coverage test suite.
layout computation: gracefully handle unsized types in unexpected locations
This PR reworks the layout computation to eagerly return an error when encountering an unsized field where a sized field was expected, rather than delaying a bug and attempting to recover a layout. This is required, because with trivially false where clauses like `[T]: Sized`, any field can possible be an unsized type, without causing a compile error.
Since this PR removes the `delayed_bug` method from the `LayoutCalculator` trait, it essentially becomes the same as the `HasDataLayout` trait, so I've also refactored the `LayoutCalculator` to be a simple wrapper struct around a type that implements `HasDataLayout`.
The majority of the diff is whitespace changes, so viewing with whitespace ignored is advised.
implements https://github.com/rust-lang/rust/pull/123169#issuecomment-2025788480
r? `@compiler-errors` or compiler
fixes https://github.com/rust-lang/rust/issues/123134
fixes https://github.com/rust-lang/rust/issues/124182
fixes https://github.com/rust-lang/rust/issues/126939
fixes https://github.com/rust-lang/rust/issues/127737
Supertraits of `BuilderMethods` are all called `XyzBuilderMethods`.
Supertraits of `CodegenMethods` are all called `XyzMethods`. This commit
changes the latter to `XyzCodegenMethods`, for consistency.
It's a trait that aggregates five other traits. But consider the places
that use it.
- `BuilderMethods`: requires three of the five traits.
- `CodegenMethods`: requires zero(!) of the five traits.
- `BaseTypeMethods`: requires two of the five traits.
- `LayoutTypeMethods`: requires three of the five traits.
- `TypeMembershipMethods`: requires one of the five traits.
This commit just removes it, which makes everything simpler.
It has `Backend` and `Deref` boudns, plus an associated type
`CodegenCx`, and it has a single use. This commit "inlines" it into
`BuilderMethods`, which makes the complicated backend trait situation a
little simpler.
It only needs `Self::Value` and `Self::Type`, so it can be a subtrait of
`BackendTypes`. That is a smaller and simpler trait than `HasCodegen`
(which includes `BackendTypes` and a lot more).
For structs that cannot be unsized, the layout algorithm sometimes moves
unsized fields to the end of the struct, which circumvented the error
for unexpected unsized fields and returned an unsized layout anyway.
This commit makes it so that the unexpected unsized error is always
returned for structs that cannot be unsized, allowing us to remove an
old hack and fixing some old ICE.
Rollup of 3 pull requests
Successful merges:
- #130033 (Don't call `fn_arg_names` query for non-`fn` foreign items in resolver)
- #130282 (Do not report an excessive number of overflow errors for an ever-growing deref impl)
- #130437 (Avoid crashing on variadic functions when producing arg-mismatch errors)
r? `@ghost`
`@rustbot` modify labels: rollup
Avoid crashing on variadic functions when producing arg-mismatch errors
Fixes#130372 by accommodating how variadic functions change the argument list length between HIR body and FnDecls.
Also degrades the zip_eq to a debug_assert! to match other asserts in the area to avoid being disruptive to users. There is at least one other crash in this area I am working on in #130400 and also considering how we might refactor some of this code to hoist some of this logic up higher.
r? `@compiler-errors`
Do not report an excessive number of overflow errors for an ever-growing deref impl
Check that we don't first hit the recursion limit in `get_field_candidates_considering_privacy` before probing for methods when we have a method lookup failure and we want to see if `.field.method()` exists. We also silence overflow error messages if we're probing for methods for diagnostics.
Also renames some functions to make it clearer that they're only for diagnostics, and sprinkle some `Autoderef::silence_errors` around to silence unnecessary overflow errors that come from diagnostics.
Fixes#130224.
Rollup of 4 pull requests
Successful merges:
- #123436 (linker: Allow MSVC to use import libraries following the Meson/MinGW convention)
- #130410 (Don't ICE when generating `Fn` shim for async closure with borrowck error)
- #130412 (Don't ICE when RPITIT captures more method args than trait definition)
- #130436 (Ignore reduce-fadd-unordered on SGX platform)
r? `@ghost`
`@rustbot` modify labels: rollup
Don't ICE when RPITIT captures more method args than trait definition
Make sure we don't ICE when an RPITIT captures more method args than the trait definition, which is not allowed. This was because we were using the wrong def id for error reporting.
Due to the default lifetime capture rules of RPITITs (capturing everything in scope), this is only doable if we use precise capturing, which isn't currently allowed for RPITITs anyways but we still end up reaching the relevant codepaths.
Fixes#129850
Don't ICE when generating `Fn` shim for async closure with borrowck error
Turn an assumption that I had originally written as an assert into a delayed bug, because this shim code is reachable even if we have borrowck errors via the MIR inliner.
Fixes#129262.
linker: Allow MSVC to use import libraries following the Meson/MinGW convention
Hi all,
This PR implements support for `MsvcLinker` to use import libraries following Meson and the MinGW toolchain's naming convention. Meson [follows the `libfoo.dll.a` naming convention](https://mesonbuild.com/FAQ.html#why-does-building-my-project-with-msvc-output-static-libraries-called-libfooa) to disambiguate between static and import libraries.
This support already existed for static libraries (see #100101), but not for dynamic libraries. The latter case was added by duplicating the logic in `native_libs::find_native_static_library`, but a separate case was added in `link_dylib_by_name` for the Windows CRT libraries which must be handled by the linker itself.
See for prerequisites #129366, #126094, and #128370.
All feedback is appreciated!
Fixes#122455
cc `@sdroege` `@nirbheek`
Don't use `typeck_root_def_id` in codegen for finding closure's root
Generating debuginfo in codegen currently peels off all the closure-specific generics (which presumably is done because they're redundant). This doesn't currently work correctly for the bodies we synthesize for async closures's returned coroutines (#128506), leading to #129702.
Specifically, `typeck_root_def_id` for some `DefKind::SyntheticCoroutineBody` just returns itself (because it loops while `is_typeck_child` is `true`, and that returns `false` for this defkind), which means we don't end up peeling off the coroutine-specific generics, and we end up encountering an otherwise unreachable `CoroutineWitness` type leading to an ICE.
This PR fixes `is_typeck_child` to consider `DefKind::SyntheticCorotuineBody` to be a typeck child, fixing `typeck_root_def_id` and suppressing this debuginfo bug.
Fixes#129702
Add system libs for LLVM when cross compiling for Windows
Windows uses "import libraries" to link to system libraries. These are a kind of static lib that are distributed with the Windows SDK and therefore they don't rely on the host. All that matters is you have the right SDK installed for the target.
Use -0.0 in `intrinsics::simd::reduce_add_unordered`
-0.0 is the actual neutral additive float, not +0.0, and this matters to codegen.
try-job: aarch64-gnu
compiler: Document AbiAndPrefAlign
The mere existence of this struct is confusing, and the second field doubly so. It's easy to mistake the "preferred" alignment as semantically relevant somehow. Insofar as I am aware, it is not, and certainly not for Rust code.
deprecate -Csoft-float because it is unsound (and not fixable)
See https://github.com/rust-lang/rust/issues/129893 for details. The general sentiment there seems to be that this flag has no use and sound alternatives exist, so let's add this warning and see if anyone out there disagrees.
Also show a different warning on targets where it does nothing (as documented since https://github.com/rust-lang/rust/pull/36261): it seems to correspond to `-mfloat-abi` in GCC/clang, which is an ARM-specific option. To be really sure it does nothing, only forward the flag to LLVM for eabihf targets. This should not change behavior but makes me sleep better ;)
interpret, miri: fix dealing with overflow during slice indexing and allocation
This is mostly to fix https://github.com/rust-lang/rust/issues/130284.
I then realized we're using somewhat sketchy arguments for a similar multiplication in `copy`/`copy_nonoverlapping`/`write_bytes`, so I made them all share the same function that checks exactly the right thing. (The intrinsics would previously fail on allocations larger than `1 << 47` bytes... which are theoretically possible maybe? Anyway it seems conceptually wrong to use any other bound than `isize::MAX` here.)
miri: treat non-memory local variables properly for data race detection
Fixes https://github.com/rust-lang/miri/issues/3242
Miri has an optimization where some local variables are not represented in memory until something forces them to be stored in memory (most notably, creating a pointer/reference to the local will do that). However, for a subsystem triggering on memory accesses -- such as the data race detector -- this means that the memory access seems to happen only when the local is moved to memory, instead of at the time that it actually happens. This can lead to UB reports in programs that do not actually have UB.
This PR fixes that by adding machine hooks for reads and writes to such efficiently represented local variables. The data race system tracks those very similar to how it would track reads and writes to addressable memory, and when a local is moved to memory, the clocks get overwritten with the information stored for the local.
Rollup of 5 pull requests
Successful merges:
- #129195 (Stabilize `&mut` (and `*mut`) as well as `&Cell` (and `*const Cell`) in const)
- #130118 (move Option::unwrap_unchecked into const_option feature gate)
- #130295 (Fix target-cpu fpu features on Armv8-R.)
- #130371 (Correctly account for niche-optimized tags in rustc_transmute)
- #130381 (library: Compute Rust exception class from its string repr)
r? `@ghost`
`@rustbot` modify labels: rollup
Correctly account for niche-optimized tags in rustc_transmute
This is a bit hacky, but it fixes the ICE and makes it possible to run the safe transmute check on every `mem::transmute` check we instantiate. I want to write a lint that needs to do that, but this stands well on its own.
cc `@jswrenn` here's the fix I alluded to yesterday :)
Fixes#123693
Fix target-cpu fpu features on Armv8-R.
This is a follow-up to #123159, but applied to Armv8-R.
This required https://github.com/llvm/llvm-project/pull/88287 to work properly. Now that this change exists in rustc's llvm, we can fix Armv8-R's default fpu features. In Armv8-R's case, the default features from LLVM for floating-point are sufficient, because there is no integer-only variant of this architecture.
Stabilize `&mut` (and `*mut`) as well as `&Cell` (and `*const Cell`) in const
This stabilizes `const_mut_refs` and `const_refs_to_cell`. That allows a bunch of new things in const contexts:
- Mentioning `&mut` types
- Creating `&mut` and `*mut` values
- Creating `&T` and `*const T` values where `T` contains interior mutability
- Dereferencing `&mut` and `*mut` values (both for reads and writes)
The same rules as at runtime apply: mutating immutable data is UB. This includes mutation through pointers derived from shared references; the following is diagnosed with a hard error:
```rust
#[allow(invalid_reference_casting)]
const _: () = {
let mut val = 15;
let ptr = &val as *const i32 as *mut i32;
unsafe { *ptr = 16; }
};
```
The main limitation that is enforced is that the final value of a const (or non-`mut` static) may not contain `&mut` values nor interior mutable `&` values. This is necessary because the memory those references point to becomes *read-only* when the constant is done computing, so (interior) mutable references to such memory would be pretty dangerous. We take a multi-layered approach here to ensuring no mutable references escape the initializer expression:
- A static analysis rejects (interior) mutable references when the referee looks like it may outlive the current MIR body.
- To be extra sure, this static check is complemented by a "safety net" of dynamic checks. ("Dynamic" in the sense of "running during/after const-evaluation, e.g. at runtime of this code" -- in contrast to "static" which works entirely by looking at the MIR without evaluating it.)
- After the final value is computed, we do a type-driven traversal of the entire value, and if we find any `&mut` or interior-mutable `&` we error out.
- However, the type-driven traversal cannot traverse `union` or raw pointers, so there is a second dynamic check where if the final value of the const contains any pointer that was not derived from a shared reference, we complain. This is currently a future-compat lint, but will become an ICE in #128543. On the off-chance that it's actually possible to trigger this lint on stable, I'd prefer if we could make it an ICE before stabilizing const_mut_refs, but it's not a hard blocker. This part of the "safety net" is only active for mutable references since with shared references, it has false positives.
Altogether this should prevent people from leaking (interior) mutable references out of the const initializer.
While updating the tests I learned that surprisingly, this code gets rejected:
```rust
const _: Vec<i32> = {
let mut x = Vec::<i32>::new(); //~ ERROR destructor of `Vec<i32>` cannot be evaluated at compile-time
let r = &mut x;
let y = x;
y
};
```
The analysis that rejects destructors in `const` is very conservative when it sees an `&mut` being created to `x`, and then considers `x` to be always live. See [here](https://github.com/rust-lang/rust/issues/65394#issuecomment-541499219) for a longer explanation. `const_precise_live_drops` will solve this, so I consider this problem to be tracked by https://github.com/rust-lang/rust/issues/73255.
Cc `@rust-lang/wg-const-eval` `@rust-lang/lang`
Cc https://github.com/rust-lang/rust/issues/57349
Cc https://github.com/rust-lang/rust/issues/80384
interpret: get_ptr_alloc_mut: lookup allocation only once
I don't think this will make a big perf difference, but it makes this function symmetric with `get_ptr_alloc` -- and it's always nice to successfully solve a borrow checker puzzle like this. ;)
This is a follow-up to #123159, but applied to Armv8-R.
This required https://github.com/llvm/llvm-project/pull/88287 to work
properly. Now that this change exists in rustc's llvm, we can fix
Armv8-R's default fpu features. In Armv8-R's case, the default features
from LLVM for floating-point are sufficient, because there is no
integer-only variant of this architecture.
Given that we directly access the graph predecessors/successors in so many
other places, and sometimes must do so to satisfy the borrow checker, there is
little value in having this trivial helper method.
- Look up the node's predecessors only once
- Get rid of some overly verbose logging
- Explain why some nodes need physical counters
- Extract a helper method to create and set a physical node counter
Make some lint doctests compatible with `--stage=0`
Currently, running `x test compiler --stage=0` (with `rust.parallel-compiler=false` to avoid other problems) results in two failures, because these lint doctests aren't compatible with the current stage0 compiler.
In theory, the more “correct” solution would be to wrap the opening triple-backtick line in `#[cfg_attr(not(bootstrap), doc = "..."]`. However, that causes a few practical problems:
- `tidy` doesn't understand that syntax, and miscounts the number of backticks in the comment block.
- `lint-docs` doesn't understand that syntax, and thinks it's trying to declare the lint name.
- Working around the above problems would cause more work and more confusion for whoever does the next bootstrap beta bump.
So instead this PR adds some bootstrap gates inside the individual doctests, which end up producing the desired behaviour, and are straightforward to remove.
stabilize `const_extern_fn`
closes https://github.com/rust-lang/rust/issues/64926
tracking issue: https://github.com/rust-lang/rust/issues/64926
reference PR: https://github.com/rust-lang/reference/pull/1596
## Stabilizaton Report
### Summary
Using `const extern "Rust"` and `const extern "C"` was already stabilized (since version 1.62.0, see https://github.com/rust-lang/rust/pull/95346). This PR stabilizes the other calling conventions: it is now possible to write `const unsafe extern "calling-convention" fn` and `const extern "calling-convention" fn` for any supported calling convention:
```rust
const extern "C-unwind" fn foo1(val: u8) -> u8 { val + 1}
const extern "stdcall" fn foo2(val: u8) -> u8 { val + 1}
const unsafe extern "C-unwind" fn bar1(val: bool) -> bool { !val }
const unsafe extern "stdcall" fn bar2(val: bool) -> bool { !val }
```
This can be used to const-ify an `extern fn`, or conversely, to make a `const fn` callable from external code.
r? T-lang
cc `@RalfJung`
const-eval interning: accept interior mutable pointers in final value
…but keep rejecting mutable references
This fixes https://github.com/rust-lang/rust/issues/121610 by no longer firing the lint when there is a pointer with interior mutability in the final value of the constant. On stable, such pointers can be created with code like:
```rust
pub enum JsValue {
Undefined,
Object(Cell<bool>),
}
impl Drop for JsValue {
fn drop(&mut self) {}
}
// This does *not* get promoted since `JsValue` has a destructor.
// However, the outer scope rule applies, still giving this 'static lifetime.
const UNDEFINED: &JsValue = &JsValue::Undefined;
```
It's not great to accept such values since people *might* think that it is legal to mutate them with unsafe code. (This is related to how "infectious" `UnsafeCell` is, which is a [wide open question](https://github.com/rust-lang/unsafe-code-guidelines/issues/236).) However, we [explicitly document](https://doc.rust-lang.org/reference/behavior-considered-undefined.html) that things created by `const` are immutable. Furthermore, we also accept the following even more questionable code without any lint today:
```rust
let x: &'static Option<Cell<i32>> = &None;
```
This is even more questionable since it does *not* involve a `const`, and yet still puts the data into immutable memory. We could view this as promotion [potentially introducing UB](https://github.com/rust-lang/unsafe-code-guidelines/issues/493). However, we've accepted this since ~forever and it's [too late to reject this now](https://github.com/rust-lang/rust/pull/122789); the pattern is just too useful.
So basically, if you think that `UnsafeCell` should be tracked fully precisely, then you should want the lint we currently emit to be removed, which this PR does. If you think `UnsafeCell` should "infect" surrounding `enum`s, the big problem is really https://github.com/rust-lang/unsafe-code-guidelines/issues/493 which does not trigger the lint -- the cases the lint triggers on are actually the "harmless" ones as there is an explicit surrounding `const` explaining why things end up being immutable.
What all this goes to show is that the hard error added in https://github.com/rust-lang/rust/pull/118324 (later turned into the future-compat lint that I am now suggesting we remove) was based on some wrong assumptions, at least insofar as it concerns shared references. Furthermore, that lint does not help at all for the most problematic case here where the potential UB is completely implicit. (In fact, the lint is actively in the way of [my preferred long-term strategy](https://github.com/rust-lang/unsafe-code-guidelines/issues/493#issuecomment-2028674105) for dealing with this UB.) So I think we should go back to square one and remove that error/lint for shared references. For mutable references, it does seem to work as intended, so we can keep it. Here it serves as a safety net in case the static checks that try to contain mutable references to the inside of a const initializer are not working as intended; I therefore made the check ICE to encourage users to tell us if that safety net is triggered.
Closes https://github.com/rust-lang/rust/issues/122153 by removing the lint.
Cc `@rust-lang/opsem` `@rust-lang/lang`
Fix `Parser::break_up_float`'s right span
```rs
use std::mem::offset_of;
fn main() {
offset_of!((u8,), 0.0);
}
```
Before:
```
error[E0609]: no field `0` on type `u8`
--> ./main.rs:4:25
|
4 | offset_of!((u8,), 0.0);
| _____--------------------^-
| | |
| | in this macro invocation
5 | | }
... |
|
= note: this error originates in the macro `offset_of` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to 1 previous error
```
After:
```
error[E0609]: no field `0` on type `u8`
--> ./main.rs:4:25
|
4 | offset_of!((u8,), 0.0);
| ^
error: aborting due to 1 previous error
```
---
`@rustbot` label +A-parser +D-imprecise-spans
simd_shuffle: require index argument to be a vector
Remove some codegen hacks by forcing the SIMD shuffle `index` argument to be a vector, which means (thanks to https://github.com/rust-lang/rust/pull/128537) that it will automatically be passed as an immediate in LLVM. The only special-casing we still have is for the extra sanity-checks we add that ensure that the indices are all in-bounds. (And the GCC backend needs to do a bunch of work since the Rust intrinsic is modeled after what LLVM expects, which seems to be quite different from what GCC expects.)
Fixes https://github.com/rust-lang/rust/issues/128738, see that issue for more context.
Simplify the canonical clone method and the copy-like forms to copy
Fixes#128081.
The optimized clone method ends up as the following MIR:
```
_2 = copy ((*_1).0: i32);
_3 = copy ((*_1).1: u64);
_4 = copy ((*_1).2: [i8; 3]);
_0 = Foo { a: move _2, b: move _3, c: move _4 };
```
We can transform this to:
```
_0 = copy (*_1);
```
r? `@cjgillot`
Fix `SDKROOT` ignore on macOS
`rustc` has code to detect when `SDKROOT` is obviously set for the wrong platform, so that it can choose to ignore it. This is a pretty important feature for Cargo build scripts and proc macros, since you will often have `SDKROOT` set to an iOS platform there.
However, the code was checking for an old SDK version name `"macosx10.15"` that was previously configured by `add_apple_sdk`, but nowadays configured to the correct `"macosx"`. I think this error was introduced in part https://github.com/rust-lang/rust/pull/77202 and in https://github.com/rust-lang/rust/pull/100286.
Fixes part of https://github.com/rust-lang/rust/issues/80817 (linking with `-Clinker=ld` now works), though more work is still needed in this area, see also https://github.com/rust-lang/rust/issues/129432.
``@rustbot`` label O-macos A-cross
(fix) conflicting negative impl marker
## Context
This MR fixes the error message for conflicting negative trait impls by adding the corresponding the polarity marker to the trait name.
## Issues
- closes#70849
r? `@fmease`
Failing to do this results in the lint example output complaining
about the lint not existing instead of the thing the lint is supposed
to be complaining about.
