Remove #[main] attribute.
This removes the #[main] attribute support from the compiler according to the decisions within #29634. For existing use cases within test harness generation, replaced it with a newly-introduced internal attribute `#[rustc_main]`.
This is first part extracted from #84062 .
Closes#29634.
r? `@petrochenkov`
Add simd_{round,trunc} intrinsics
LLVM supports many functions from math.h in its IR. Many of these
have SIMD instructions on various platforms. So, let's add round and
trunc so std::arch can use them.
Yes, exact comparison is intentional: rounding must always return a
valid integer-equal value, except for inf/NAN.
Update docs for unsafe_op_in_unsafe_fn stability.
The unsafe_op_in_unsafe_fn lint was stabilized in #79208, but the bottom of this documentation wasn't updated.
I'm just guessing at the reason here, hopefully it is close to correct. The only discussion I found is https://github.com/rust-lang/rust/issues/71668#issuecomment-730399862 which didn't really explain the thought process behind the decision.
LLVM supports many functions from math.h in its IR. Many of these have
single-instruction variants on various platforms. So, let's add them so
std::arch can use them.
Yes, exact comparison is intentional: rounding must always return a
valid integer-equal value, except for inf/NAN.
add lint deref_nullptr detecting when a null ptr is dereferenced
fixes#83856
changelog: add lint that detect code like
```rust
unsafe {
&*core::ptr::null::<i32>()
};
unsafe {
addr_of!(std::ptr::null::<i32>())
};
let x: i32 = unsafe {*core::ptr::null()};
let x: i32 = unsafe {*core::ptr::null_mut()};
unsafe {*(0 as *const i32)};
unsafe {*(core::ptr::null() as *const i32)};
```
```
warning: Dereferencing a null pointer causes undefined behavior
--> src\main.rs:5:26
|
5 | let x: i32 = unsafe {*core::ptr::null()};
| ^^^^^^^^^^^^^^^^^^
| |
| a null pointer is dereferenced
| this code causes undefined behavior when executed
|
= note: `#[warn(deref_nullptr)]` on by default
```
Limitation:
It does not detect code like
```rust
const ZERO: usize = 0;
unsafe {*(ZERO as *const i32)};
```
or code where `0` is not directly a literal
Avoid an `Option<Option<_>>`
By simply swapping the calls to `map` and `and_then` around the complexity of
handling an `Option<Option<_>>` disappears.
`@rustbot` modify labels +C-cleanup +T-compiler
Fix typo in error message
Also tweaked the message a bit by
- removing the hyphen, because in my opinion the hyphen makes the
message a bit harder to read, especially combined with the backticks;
- adding the word "be", because I think it's a bit clearer that way.
Also tweaked the message a bit by
- removing the hyphen, because in my opinion the hyphen makes the
message a bit harder to read, especially combined with the backticks;
- adding the word "be", because I think it's a bit clearer that way.
Improve trait/impl method discrepancy errors
* Use more accurate spans
* Clean up some code by removing previous hack
* Provide structured suggestions
Structured suggestions are particularly useful for cases where arbitrary self types are used, like in custom `Future`s, because the way to write `self: Pin<&mut Self>` is not necessarily self-evident when first encountered.
Issue 81508 fix
Fix#81508
**Problem**: When variable name is used incorrectly as path, error and warning point to undeclared/unused name, when in fact the name is used, just incorrectly (should be used as a variable, not part of a path).
**Summary for fix**: When path resolution errs, diagnostics checks for variables in ```ValueNS``` that have the same name (e.g., variable rather than path named Foo), and adds additional suggestion that user may actually intend to use the variable name rather than a path.
The fix does not suppress or otherwise change the *warning* that results. I did not find a straightforward way in the code to modify this, but would love to make changes here as well with any guidance.
This PR modifies the macro expansion infrastructure to handle attributes
in a fully token-based manner. As a result:
* Derives macros no longer lose spans when their input is modified
by eager cfg-expansion. This is accomplished by performing eager
cfg-expansion on the token stream that we pass to the derive
proc-macro
* Inner attributes now preserve spans in all cases, including when we
have multiple inner attributes in a row.
This is accomplished through the following changes:
* New structs `AttrAnnotatedTokenStream` and `AttrAnnotatedTokenTree` are introduced.
These are very similar to a normal `TokenTree`, but they also track
the position of attributes and attribute targets within the stream.
They are built when we collect tokens during parsing.
An `AttrAnnotatedTokenStream` is converted to a regular `TokenStream` when
we invoke a macro.
* Token capturing and `LazyTokenStream` are modified to work with
`AttrAnnotatedTokenStream`. A new `ReplaceRange` type is introduced, which
is created during the parsing of a nested AST node to make the 'outer'
AST node aware of the attributes and attribute target stored deeper in the token stream.
* When we need to perform eager cfg-expansion (either due to `#[derive]` or `#[cfg_eval]`),
we tokenize and reparse our target, capturing additional information about the locations of
`#[cfg]` and `#[cfg_attr]` attributes at any depth within the target.
This is a performance optimization, allowing us to perform less work
in the typical case where captured tokens never have eager cfg-expansion run.
Expand derive invocations in left-to-right order
While derives were being collected in left-to-order order, the
corresponding `Invocation`s were being pushed in the wrong order.
Avoid `;` -> `,` recovery and unclosed `}` recovery from being too verbose
Those two recovery attempts have a very bad interaction that causes too
unnecessary output. Add a simple gate to avoid interpreting a `;` as a
`,` when there are unclosed braces.
Fix#83498.
Categorize and explain target features support
There are 3 different uses of the `-C target-feature` args passed to rustc:
1. All of the features are passed to LLVM, which uses them to configure code-generation. This is sort-of stabilized since 1.0 though LLVM does change/add/remove target features regularly.
2. Target features which are in [the compiler's allowlist](69e1d22ddb/compiler/rustc_codegen_ssa/src/target_features.rs (L12-L34)) can be used in `cfg!(target_feature)` etc. These may have different names than in LLVM and are renamed before passing them to LLVM.
3. Target features which are in the allowlist and which are stabilized or feature-gate-enabled can be used in `#[target_feature]`.
It can be confusing that `rustc --print target-features` just prints out the LLVM features without separating out the rustc features or even mentioning that the dichotomy exists.
This improves the situation by separating out the rustc and LLVM target features and adding a brief explanation about the difference.
Abbreviated Example Output:
```
$ rustc --print target-features
Features supported by rustc for this target:
adx - Support ADX instructions.
aes - Enable AES instructions.
...
xsaves - Support xsaves instructions.
crt-static - Enables libraries with C Run-time Libraries(CRT) to be statically linked.
Code-generation features supported by LLVM for this target:
16bit-mode - 16-bit mode (i8086).
32bit-mode - 32-bit mode (80386).
...
x87 - Enable X87 float instructions.
xop - Enable XOP instructions.
Use +feature to enable a feature, or -feature to disable it.
For example, rustc -C target-cpu=mycpu -C target-feature=+feature1,-feature2
Code-generation features cannot be used in cfg or #[target_feature],
and may be renamed or removed in a future version of LLVM or rustc.
```
Motivated by #83975.
CC https://github.com/rust-lang/rust/issues/49653
Those two recovery attempts have a very bad interaction that causes too
unnecessary output. Add a simple gate to avoid interpreting a `;` as a
`,` when there are unclosed braces.
Don't concatenate binders across types
Partially addresses #83737
There's actually two issues that I uncovered in #83737. The first is that we are concatenating bound vars across types, i.e. in
```
F: Fn(&()) -> &mut (dyn Future<Output = ()> + Unpin)
```
the bound vars on `Future` get set as `for<anon>` since those are the binders on `Fn(&()`. This is obviously wrong, since we should only concatenate directly nested trait refs. This is solved here by introducing a new `TraitRefBoundary` scope, that we put around the "syntactical" trait refs and basically don't allow concatenation across.
Now, this alone *shouldn't* be a super terrible problem. At least not until you consider the other issue, which is a much more elusive and harder to design a "perfect" fix. A repro can be seen in:
```
use core::future::Future;
async fn handle<F>(slf: &F)
where
F: Fn(&()) -> &mut (dyn for<'a> Future<Output = ()> + Unpin),
{
(slf)(&()).await;
}
```
Notice the `for<'a>` around `Future`. Here, `'a` is unused, so the `for<'a>` Binder gets changed to a `for<>` Binder in the generator witness, but the "local decl" still has it. This has heavy intersections with region anonymization and erasing. Luckily, it's not *super* common to find this unique set of circumstances. It only became apparently because of the first issue mentioned here. However, this *is* still a problem, so I'm leaving #83737 open.
r? `@nikomatsakis`
The issue was that the resulting debuginfo was too complex for LLVM to
translate into CodeView records correctly. As a result, it simply
ignored the debuginfo which meant Windows debuggers could not display
any closed over variables when stepping inside a closure.
This fixes that by spilling additional variables to the stack so that
the resulting debuginfo is simple (just `*my_variable.dbg.spill`) and
LLVM can generate the correct CV records.
