[Coverage][MCDC] Adapt mcdc to llvm 19
Related issue: #126672
Also finish task 4 at #124144
[llvm #82448](https://github.com/llvm/llvm-project/pull/82448) has introduced some break changes into mcdc, causing incompatibility between llvm 18 and 19. This draft adapts to that change and gives up supporting for llvm-18.
Fix utf8-bom test
The BOM was accidentally removed in https://github.com/rust-lang/rust/pull/57108
I had to move the run-pass line down, because compiletest doesn't seem to know about BOMs, so it does not parse the header if it is the first line.
Add tests for some old fixed issues
Closes#30867Closes#30472Closes#28994Closes#26719 (and migrates the relevant test to the new run-make)
Closes#23600
cc `@jieyouxu` for the run-make-support changes
try-job: x86_64-msvc
Add missing module flags for `-Zfunction-return=thunk-extern`
This fixes a bug in the `-Zfunction-return=thunk-extern` flag. The flag needs to be passed onto LLVM to ensure that functions such as `asan.module_ctor` and `asan.module_dtor` that are created internally in LLVM have the mitigation applied to them.
This was originally discovered [in the Linux kernel](https://lore.kernel.org/all/CANiq72myZL4_poCMuNFevtpYYc0V0embjSuKb7y=C+m3vVA_8g@mail.gmail.com/).
Original flag PR: #116892
PR for similar issue: #129373
Tracking issue: #116853
cc ``@ojeda``
r? ``@wesleywiser``
Add precondition checks to ptr::offset, ptr::add, ptr::sub
All of `offset`, `add`, and `sub` (currently) have the trivial preconditions that the offset in bytes must be <= isize::MAX, and the computation of the new address must not wrap. This adds precondition checks for these, and like in slice indexing, we use intrinsics directly to implement unsafe APIs that have explicit checks, because we get a clearer error message that mentions the misused API not an implementation detail.
Experimentation indicates these checks have 1-2% compile time overhead, due primarily to adding the checks for `add`.
A crater run (https://github.com/rust-lang/rust/pull/130251#issuecomment-2395824565) indicates some people currently have buggy calls to `ptr::offset` that apply a negative offset to a null pointer, but the crater run does not hit the `ptr::add` or `ptr::sub` checks, which seems like an argument for cfg'ing out those checks on account of their overhead.
Don't allow the `#[pointee]` attribute where it doesn't belong
Error if the `#[pointee]` attribute is applied to anything but generic type parameters.
Closes#128485
Related to #123430
liballoc: introduce String, Vec const-slicing
This change `const`-qualifies many methods on `Vec` and `String`, notably `as_slice`, `as_str`, `len`. These changes are made behind the unstable feature flag `const_vec_string_slice`.
## Motivation
This is to support simultaneous variance over ownership and constness. I have an enum type that may contain either `String` or `&str`, and I want to produce a `&str` from it in a possibly-`const` context.
```rust
enum StrOrString<'s> {
Str(&'s str),
String(String),
}
impl<'s> StrOrString<'s> {
const fn as_str(&self) -> &str {
match self {
// In a const-context, I really only expect to see this variant, but I can't switch the implementation
// in some mode like #[cfg(const)] -- there has to be a single body
Self::Str(s) => s,
// so this is a problem, since it's not `const`
Self::String(s) => s.as_str(),
}
}
}
```
Currently `String` and `Vec` don't support this, but can without functional changes. Similar logic applies for `len`, `capacity`, `is_empty`.
## Changes
The essential thing enabling this change is that `Unique::as_ptr` is `const`. This lets us convert `RawVec::ptr` -> `Vec::as_ptr` -> `Vec::as_slice` -> `String::as_str`.
I had to move the `Deref` implementations into `as_{str,slice}` because `Deref` isn't `#[const_trait]`, but I would expect this change to be invisible up to inlining. I moved the `DerefMut` implementations as well for uniformity.
Don't use Immediate::offset to transmute pointers to integers
This applies the relatively new `assert_matches_abi` check in the `offset` operation on immediates, which makes sure that if offsets are used to alter the layout (which is possible because the field layout is arbitrarily picked by the caller), this is not done in a way that breaks the invariant of the `Immediate` type.
This leads to ICEs in a GVN mir-opt test, so the second commit fixes GVN.
Fixes https://github.com/rust-lang/rust/issues/131064.
This change `const`-qualifies many methods on Vec and String, notably
`as_slice`, `as_str`, `len`. These changes are made behind the unstable
feature flag `const_vec_string_slice` with the following tracking issue:
https://github.com/rust-lang/rust/issues/129041
add `naked_asm!` macro for use in `#[naked]` functions
tracking issue: https://github.com/rust-lang/rust/issues/90957
Adds the `core::arch::naked_asm` macro, to be used in `#[naked]` functions, but providing better error messages and a place to explain the restrictions on assembly in naked functions.
This PR does not yet require that the `naked_asm!` macro is used inside of `#[naked]` functions:
- the `asm!` macro can still be used in `#[naked]` functions currently, with the same restrictions and error messages as before.
- the `naked_asm!` macro can be used outside of `#[naked]` functions. It has not yet been decided whether that should be allowed long-term.
In this PR, the parsing code of `naked_asm!` now enforces the restrictions on assembly in naked functions, with the exception of checking that the `noreturn` option is specified. It also has not currently been decided if `noreturn` should be implicit or not.
This PR looks large because it touches a bunch of tests. The code changes are mostly straightforward I think: we now have 3 flavors of assembly macro, and that information must be propagated through the parsing code and error messages.
cc `@Lokathor`
r? `@Amanieu`
- fix for divergence
- fix error message
- fix another cranelift test
- fix some cranelift things
- don't set the NORETURN option for naked asm
- fix use of naked_asm! in doc comment
- fix use of naked_asm! in run-make test
- use `span_bug` in unreachable branch
Make deprecated_cfg_attr_crate_type_name a hard error
Turns the forward compatibility lint added by #83744 into a hard error, so now, while the `#![crate_name]` and `#![crate_type]` attributes are still allowed in raw form, they are now forbidden to be nested inside a `#![cfg_attr()]` attribute.
The following will now be an error:
```Rust
#![cfg_attr(foo, crate_name = "foobar")]
#![cfg_attr(foo, crate_type = "bin")]
```
This code will continue working and is not deprecated:
```Rust
#![crate_name = "foobar"]
#![crate_type = "lib"]
```
The reasoning for this is explained in #83744: it allows us to not have to cfg-expand in order to determine the crate's type and name.
As of filing the PR, exactly two years have passed since #99784 has been merged, which has turned the lint's default warning level into an error, so there has been ample time to move off the now-forbidden syntax.
cc #91632 - tracking issue for the lint
On function and method calls in patterns, link to the book
```
error: expected a pattern, found an expression
--> f889.rs:3:13
|
3 | let (x, y.drop()) = (1, 2);
| ^^^^^^^^ not a pattern
|
= note: arbitrary expressions are not allowed in patterns: <https://doc.rust-lang.org/book/ch18-00-patterns.html>
error[E0532]: expected a pattern, found a function call
--> f889.rs:2:13
|
2 | let (x, drop(y)) = (1, 2);
| ^^^^ not a tuple struct or tuple variant
|
= note: function calls are not allowed in patterns: <https://doc.rust-lang.org/book/ch18-00-patterns.html>
```
Fix#97200.
Do not consider match/let/ref of place that evaluates to `!` to diverge, disallow coercions from them too
Fixes#117288.
This PR implements a heuristic which disables two things that are currently being performed on the HIR when we have **expressions that involve place-like expressions that point to `!`**. Specifically, it will (in certain cases explained below):
### (1.) Disable the `NeverToAny` coercion we implicitly insert for `!`.
Which fixes this inadvertent, sneaky unsoundness:
```
unsafe {
let x: *const ! = &0 as *const u8 as *const !;
let _: () = *x;
}
```
which is UB because currently rust emits an *implicit* NeverToAny coercion even though we really shouldn't be, since there's no read of the value pointed by `x`.
### (2.) Disable the logic which considers expression which evaluate to `!` to diverge, which affects the type returned by the containing block.
Which fixes this unsoundness:
```
fn make_up_a_value<T>() -> T {
unsafe {
let x: *const ! = &0 as *const u8 as *const !;
let _ = *x;
}
}
```
We disable these two operations **if** the expression is a place-like expression (locals, statics, field projections, index operations, and deref operations), and if the parent expression is either:
(1.) the LHS of an assignment
(2.) AddrOf
(3.) A match or let **unless** all of the *patterns consitute a read*, which is explained below:
And finally, a pattern currently is considered to constitute a read **unless** it is a wildcard, or an OR pattern. An OR pattern is considered to constitute a read if all of its subpatterns constitute a read, to remain as conservative as possible in cases like `_ | subpat` or `subpat | _`.
All other patterns are considered currently to constitute a read. Specifically, because `NeverToAny` is a coercion performed on a *value* and not a *place*, `Struct { .. }` on a `!` type must be a coercion currently, and we currently rely on this behavior to allow us to perform coercions like `let _: i32 = x;` where `x: !`.
This is already considered UB by [miri](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=daf3a2246433fe43fdc07d1389c276c9), but also means it does not affect the preexisting UB in this case:
```
let Struct { .. } = *never_ptr;
```
Even though it's likely up for debate since we're not actually reading any data out of the struct, it almost certainly causes inference changes which I do *NOT* want to fix in this PR.
```
error: expected a pattern, found an expression
--> f889.rs:3:13
|
3 | let (x, y.drop()) = (1, 2); //~ ERROR
| ^^^^^^^^ not a pattern
|
= note: arbitrary expressions are not allowed in patterns: <https://doc.rust-lang.org/book/ch18-00-patterns.html>
error[E0532]: expected a pattern, found a function call
--> f889.rs:2:13
|
2 | let (x, drop(y)) = (1, 2); //~ ERROR
| ^^^^ not a tuple struct or tuple variant
|
= note: function calls are not allowed in patterns: <https://doc.rust-lang.org/book/ch18-00-patterns.html>
```
Fix#97200.
Initial support for riscv32{e|em|emc}_unknown_none_elf
We have a research prototype of an RV32EMC target and have been successfully running the e, em, emc programs on it. I'm hoping upstreaming this configuration would make the target maintenance slightly easier.
Configuration is based on the respective {i, im, imc} variants. As defined in RISC-V Unprivileged Spec. 20191213, the only change in RVE wrt. RVI is to reduce the number of integer registers to 16 (x0-x15), which also implies
- 2 callee saved registers instead of 12
- 32-bit / 4-byte stack alignment instead of 128 bits / 16 bytes
My initial presumption is that this will not impact how the target is defined for the compiler but only becomes relevant at the runtime level. I am willing to investigate, though.
EDIT: LLVM is now told about the presumed 32-bit stack alignment.
`@Disasm` `@romancardenas`
