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Auto merge of #128771 - carbotaniuman:stabilize_unsafe_attr, r=nnethercote

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Stabilize `unsafe_attributes`

# Stabilization report

## Summary

This is a tracking issue for the RFC 3325: unsafe attributes

We are stabilizing `#![feature(unsafe_attributes)]`,  which makes certain attributes considered 'unsafe', meaning that they must be surrounded by an `unsafe(...)`, as in `#[unsafe(no_mangle)]`.

RFC: rust-lang/rfcs#3325
Tracking issue: #123757

## What is stabilized

### Summary of stabilization

Certain attributes will now be designated as unsafe attributes, namely, `no_mangle`, `export_name`, and `link_section` (stable only), and these attributes will need to be called by surrounding them in `unsafe(...)` syntax. On editions prior to 2024, this is simply an edition lint, but it will become a hard error in 2024. This also works in `cfg_attr`, but `unsafe` is not allowed for any other attributes, including proc-macros ones.

```rust
#[unsafe(no_mangle)]
fn a() {}

#[cfg_attr(any(), unsafe(export_name = "c"))]
fn b() {}
```

For a table showing the attributes that were considered to be included in the list to require unsafe, and subsequent reasoning about why each such attribute was or was not included, see [this comment here](https://github.com/rust-lang/rust/pull/124214#issuecomment-2124753464)

## Tests

The relevant tests are in `tests/ui/rust-2024/unsafe-attributes` and `tests/ui/attributes/unsafe`.
This commit is contained in:
bors 2024-08-17 22:48:42 +00:00
commit 37d56daac6
37 changed files with 64 additions and 134 deletions
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4
compiler/rustc_parse/src/parser/attr.rs
View file

@ -4,7 +4,7 @@ use rustc_ast::token::{self, Delimiter};
use rustc_errors::codes::*;
use rustc_errors::{Diag, PResult};
use rustc_span::symbol::kw;
use rustc_span::{sym, BytePos, Span};
use rustc_span::{BytePos, Span};
use thin_vec::ThinVec;
use tracing::debug;
@ -265,7 +265,6 @@ impl<'a> Parser<'a> {
let is_unsafe = this.eat_keyword(kw::Unsafe);
let unsafety = if is_unsafe {
let unsafe_span = this.prev_token.span;
this.psess.gated_spans.gate(sym::unsafe_attributes, unsafe_span);
this.expect(&token::OpenDelim(Delimiter::Parenthesis))?;
ast::Safety::Unsafe(unsafe_span)
} else {
@ -406,7 +405,6 @@ impl<'a> Parser<'a> {
};
let unsafety = if is_unsafe {
let unsafe_span = self.prev_token.span;
self.psess.gated_spans.gate(sym::unsafe_attributes, unsafe_span);
self.expect(&token::OpenDelim(Delimiter::Parenthesis))?;
ast::Safety::Unsafe(unsafe_span)

40
compiler/rustc_parse/src/validate_attr.rs
View file

@ -7,9 +7,7 @@ use rustc_ast::{
NestedMetaItem, Safety,
};
use rustc_errors::{Applicability, FatalError, PResult};
use rustc_feature::{
AttributeSafety, AttributeTemplate, BuiltinAttribute, Features, BUILTIN_ATTRIBUTE_MAP,
};
use rustc_feature::{AttributeSafety, AttributeTemplate, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
use rustc_session::errors::report_lit_error;
use rustc_session::lint::builtin::{ILL_FORMED_ATTRIBUTE_INPUT, UNSAFE_ATTR_OUTSIDE_UNSAFE};
use rustc_session::lint::BuiltinLintDiag;
@ -18,7 +16,7 @@ use rustc_span::{sym, BytePos, Span, Symbol};
use crate::{errors, parse_in};
pub fn check_attr(features: &Features, psess: &ParseSess, attr: &Attribute) {
pub fn check_attr(psess: &ParseSess, attr: &Attribute) {
if attr.is_doc_comment() {
return;
}
@ -28,7 +26,7 @@ pub fn check_attr(features: &Features, psess: &ParseSess, attr: &Attribute) {
// All non-builtin attributes are considered safe
let safety = attr_info.map(|x| x.safety).unwrap_or(AttributeSafety::Normal);
check_attribute_safety(features, psess, safety, attr);
check_attribute_safety(psess, safety, attr);
// Check input tokens for built-in and key-value attributes.
match attr_info {
@ -36,9 +34,9 @@ pub fn check_attr(features: &Features, psess: &ParseSess, attr: &Attribute) {
Some(BuiltinAttribute { name, template, .. }) if *name != sym::rustc_dummy => {
match parse_meta(psess, attr) {
// Don't check safety again, we just did that
Ok(meta) => check_builtin_meta_item(
features, psess, &meta, attr.style, *name, *template, false,
),
Ok(meta) => {
check_builtin_meta_item(psess, &meta, attr.style, *name, *template, false)
}
Err(err) => {
err.emit();
}
@ -157,16 +155,7 @@ fn is_attr_template_compatible(template: &AttributeTemplate, meta: &ast::MetaIte
}
}
pub fn check_attribute_safety(
features: &Features,
psess: &ParseSess,
safety: AttributeSafety,
attr: &Attribute,
) {
if !features.unsafe_attributes {
return;
}
pub fn check_attribute_safety(psess: &ParseSess, safety: AttributeSafety, attr: &Attribute) {
let attr_item = attr.get_normal_item();
if safety == AttributeSafety::Unsafe {
@ -215,21 +204,18 @@ pub fn check_attribute_safety(
// Called by `check_builtin_meta_item` and code that manually denies
// `unsafe(...)` in `cfg`
pub fn deny_builtin_meta_unsafety(features: &Features, psess: &ParseSess, meta: &MetaItem) {
pub fn deny_builtin_meta_unsafety(psess: &ParseSess, meta: &MetaItem) {
// This only supports denying unsafety right now - making builtin attributes
// support unsafety will requite us to thread the actual `Attribute` through
// for the nice diagnostics.
if features.unsafe_attributes {
if let Safety::Unsafe(unsafe_span) = meta.unsafety {
psess
.dcx()
.emit_err(errors::InvalidAttrUnsafe { span: unsafe_span, name: meta.path.clone() });
}
if let Safety::Unsafe(unsafe_span) = meta.unsafety {
psess
.dcx()
.emit_err(errors::InvalidAttrUnsafe { span: unsafe_span, name: meta.path.clone() });
}
}
pub fn check_builtin_meta_item(
features: &Features,
psess: &ParseSess,
meta: &MetaItem,
style: ast::AttrStyle,
@ -246,7 +232,7 @@ pub fn check_builtin_meta_item(
}
if deny_unsafety {
deny_builtin_meta_unsafety(features, psess, meta);
deny_builtin_meta_unsafety(psess, meta);
}
}