f1b1ed7e18
Remove `box_syntax` r? `@Nilstrieb` This removes the feature `box_syntax`, which allows the use of `box <expr>` to create a Box, and finalises removing use of the feature from the compiler. `box_patterns` (allowing the use of `box <pat>` in a pattern) is unaffected. It also removes `ast::ExprKind::Box` - the only way to create a 'box' expression now is with the rustc-internal `#[rustc_box]` attribute. As a temporary measure to help users move away, `box <expr>` now parses the inner expression, and emits a `MachineApplicable` lint to replace it with `Box::new` Closes #49733
667 lines
26 KiB
Rust
667 lines
26 KiB
Rust
use rustc_ast as ast;
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use rustc_ast::visit::{self, AssocCtxt, FnCtxt, FnKind, Visitor};
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use rustc_ast::{AssocConstraint, AssocConstraintKind, NodeId};
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use rustc_ast::{PatKind, RangeEnd};
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use rustc_errors::{Applicability, StashKey};
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use rustc_feature::{AttributeGate, BuiltinAttribute, Features, GateIssue, BUILTIN_ATTRIBUTE_MAP};
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use rustc_session::parse::{feature_err, feature_err_issue, feature_warn};
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use rustc_session::Session;
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use rustc_span::source_map::Spanned;
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use rustc_span::symbol::sym;
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use rustc_span::Span;
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use rustc_target::spec::abi;
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use thin_vec::ThinVec;
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use tracing::debug;
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use crate::errors;
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macro_rules! gate_feature_fn {
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($visitor: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr, $help: expr) => {{
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let (visitor, has_feature, span, name, explain, help) =
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(&*$visitor, $has_feature, $span, $name, $explain, $help);
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let has_feature: bool = has_feature(visitor.features);
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debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature);
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if !has_feature && !span.allows_unstable($name) {
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feature_err(&visitor.sess.parse_sess, name, span, explain).help(help).emit();
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}
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}};
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($visitor: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr) => {{
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let (visitor, has_feature, span, name, explain) =
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(&*$visitor, $has_feature, $span, $name, $explain);
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let has_feature: bool = has_feature(visitor.features);
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debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature);
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if !has_feature && !span.allows_unstable($name) {
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feature_err(&visitor.sess.parse_sess, name, span, explain).emit();
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}
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}};
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(future_incompatible; $visitor: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr) => {{
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let (visitor, has_feature, span, name, explain) =
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(&*$visitor, $has_feature, $span, $name, $explain);
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let has_feature: bool = has_feature(visitor.features);
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debug!(
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"gate_feature(feature = {:?}, span = {:?}); has? {} (future_incompatible)",
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name, span, has_feature
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);
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if !has_feature && !span.allows_unstable($name) {
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feature_warn(&visitor.sess.parse_sess, name, span, explain);
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}
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}};
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}
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macro_rules! gate_feature_post {
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($visitor: expr, $feature: ident, $span: expr, $explain: expr, $help: expr) => {
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gate_feature_fn!($visitor, |x: &Features| x.$feature, $span, sym::$feature, $explain, $help)
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};
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($visitor: expr, $feature: ident, $span: expr, $explain: expr) => {
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gate_feature_fn!($visitor, |x: &Features| x.$feature, $span, sym::$feature, $explain)
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};
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(future_incompatible; $visitor: expr, $feature: ident, $span: expr, $explain: expr) => {
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gate_feature_fn!(future_incompatible; $visitor, |x: &Features| x.$feature, $span, sym::$feature, $explain)
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};
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}
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pub fn check_attribute(attr: &ast::Attribute, sess: &Session, features: &Features) {
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PostExpansionVisitor { sess, features }.visit_attribute(attr)
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}
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struct PostExpansionVisitor<'a> {
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sess: &'a Session,
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// `sess` contains a `Features`, but this might not be that one.
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features: &'a Features,
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}
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impl<'a> PostExpansionVisitor<'a> {
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fn check_abi(&self, abi: ast::StrLit, constness: ast::Const) {
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let ast::StrLit { symbol_unescaped, span, .. } = abi;
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if let ast::Const::Yes(_) = constness {
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match symbol_unescaped {
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// Stable
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sym::Rust | sym::C => {}
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abi => gate_feature_post!(
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&self,
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const_extern_fn,
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span,
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&format!("`{}` as a `const fn` ABI is unstable", abi)
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),
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}
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}
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match abi::is_enabled(&self.features, span, symbol_unescaped.as_str()) {
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Ok(()) => (),
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Err(abi::AbiDisabled::Unstable { feature, explain }) => {
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feature_err_issue(
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&self.sess.parse_sess,
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feature,
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span,
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GateIssue::Language,
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explain,
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)
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.emit();
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}
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Err(abi::AbiDisabled::Unrecognized) => {
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if self.sess.opts.pretty.map_or(true, |ppm| ppm.needs_hir()) {
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self.sess.parse_sess.span_diagnostic.delay_span_bug(
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span,
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&format!(
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"unrecognized ABI not caught in lowering: {}",
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symbol_unescaped.as_str()
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),
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);
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}
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}
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}
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}
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fn check_extern(&self, ext: ast::Extern, constness: ast::Const) {
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if let ast::Extern::Explicit(abi, _) = ext {
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self.check_abi(abi, constness);
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}
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}
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/// Feature gate `impl Trait` inside `type Alias = $type_expr;`.
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fn check_impl_trait(&self, ty: &ast::Ty) {
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struct ImplTraitVisitor<'a> {
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vis: &'a PostExpansionVisitor<'a>,
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}
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impl Visitor<'_> for ImplTraitVisitor<'_> {
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fn visit_ty(&mut self, ty: &ast::Ty) {
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if let ast::TyKind::ImplTrait(..) = ty.kind {
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gate_feature_post!(
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&self.vis,
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type_alias_impl_trait,
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ty.span,
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"`impl Trait` in type aliases is unstable"
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);
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}
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visit::walk_ty(self, ty);
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}
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}
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ImplTraitVisitor { vis: self }.visit_ty(ty);
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}
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fn check_late_bound_lifetime_defs(&self, params: &[ast::GenericParam]) {
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// Check only lifetime parameters are present and that the lifetime
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// parameters that are present have no bounds.
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let non_lt_param_spans: Vec<_> = params
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.iter()
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.filter_map(|param| match param.kind {
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ast::GenericParamKind::Lifetime { .. } => None,
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_ => Some(param.ident.span),
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})
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.collect();
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// FIXME: gate_feature_post doesn't really handle multispans...
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if !non_lt_param_spans.is_empty() && !self.features.non_lifetime_binders {
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feature_err(
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&self.sess.parse_sess,
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sym::non_lifetime_binders,
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non_lt_param_spans,
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crate::fluent_generated::ast_passes_forbidden_non_lifetime_param,
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)
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.emit();
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}
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for param in params {
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if !param.bounds.is_empty() {
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let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect();
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self.sess.emit_err(errors::ForbiddenLifetimeBound { spans });
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}
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}
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}
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}
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impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
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fn visit_attribute(&mut self, attr: &ast::Attribute) {
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let attr_info = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name));
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// Check feature gates for built-in attributes.
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if let Some(BuiltinAttribute {
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gate: AttributeGate::Gated(_, name, descr, has_feature),
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..
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}) = attr_info
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{
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gate_feature_fn!(self, has_feature, attr.span, *name, *descr);
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}
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// Check unstable flavors of the `#[doc]` attribute.
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if attr.has_name(sym::doc) {
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for nested_meta in attr.meta_item_list().unwrap_or_default() {
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macro_rules! gate_doc { ($($name:ident => $feature:ident)*) => {
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$(if nested_meta.has_name(sym::$name) {
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let msg = concat!("`#[doc(", stringify!($name), ")]` is experimental");
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gate_feature_post!(self, $feature, attr.span, msg);
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})*
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}}
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gate_doc!(
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cfg => doc_cfg
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cfg_hide => doc_cfg_hide
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masked => doc_masked
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notable_trait => doc_notable_trait
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);
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if nested_meta.has_name(sym::keyword) {
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let msg = "`#[doc(keyword)]` is meant for internal use only";
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gate_feature_post!(self, rustdoc_internals, attr.span, msg);
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}
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if nested_meta.has_name(sym::fake_variadic) {
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let msg = "`#[doc(fake_variadic)]` is meant for internal use only";
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gate_feature_post!(self, rustdoc_internals, attr.span, msg);
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}
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}
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}
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// Emit errors for non-staged-api crates.
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if !self.features.staged_api {
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if attr.has_name(sym::unstable)
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|| attr.has_name(sym::stable)
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|| attr.has_name(sym::rustc_const_unstable)
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|| attr.has_name(sym::rustc_const_stable)
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|| attr.has_name(sym::rustc_default_body_unstable)
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{
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self.sess.emit_err(errors::StabilityOutsideStd { span: attr.span });
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}
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}
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}
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fn visit_item(&mut self, i: &'a ast::Item) {
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match &i.kind {
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ast::ItemKind::ForeignMod(foreign_module) => {
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if let Some(abi) = foreign_module.abi {
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self.check_abi(abi, ast::Const::No);
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}
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}
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ast::ItemKind::Fn(..) => {
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if self.sess.contains_name(&i.attrs, sym::start) {
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gate_feature_post!(
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&self,
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start,
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i.span,
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"`#[start]` functions are experimental \
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and their signature may change \
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over time"
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);
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}
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}
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ast::ItemKind::Struct(..) => {
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for attr in self.sess.filter_by_name(&i.attrs, sym::repr) {
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for item in attr.meta_item_list().unwrap_or_else(ThinVec::new) {
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if item.has_name(sym::simd) {
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gate_feature_post!(
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&self,
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repr_simd,
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attr.span,
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"SIMD types are experimental and possibly buggy"
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);
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}
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}
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}
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}
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ast::ItemKind::Impl(box ast::Impl { polarity, defaultness, of_trait, .. }) => {
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if let &ast::ImplPolarity::Negative(span) = polarity {
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gate_feature_post!(
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&self,
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negative_impls,
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span.to(of_trait.as_ref().map_or(span, |t| t.path.span)),
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"negative trait bounds are not yet fully implemented; \
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use marker types for now"
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);
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}
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if let ast::Defaultness::Default(_) = defaultness {
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gate_feature_post!(&self, specialization, i.span, "specialization is unstable");
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}
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}
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ast::ItemKind::Trait(box ast::Trait { is_auto: ast::IsAuto::Yes, .. }) => {
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gate_feature_post!(
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&self,
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auto_traits,
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i.span,
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"auto traits are experimental and possibly buggy"
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);
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}
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ast::ItemKind::TraitAlias(..) => {
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gate_feature_post!(&self, trait_alias, i.span, "trait aliases are experimental");
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}
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ast::ItemKind::MacroDef(ast::MacroDef { macro_rules: false, .. }) => {
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let msg = "`macro` is experimental";
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gate_feature_post!(&self, decl_macro, i.span, msg);
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}
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ast::ItemKind::TyAlias(box ast::TyAlias { ty: Some(ty), .. }) => {
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self.check_impl_trait(&ty)
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}
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_ => {}
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}
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visit::walk_item(self, i);
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}
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fn visit_foreign_item(&mut self, i: &'a ast::ForeignItem) {
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match i.kind {
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ast::ForeignItemKind::Fn(..) | ast::ForeignItemKind::Static(..) => {
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let link_name = self.sess.first_attr_value_str_by_name(&i.attrs, sym::link_name);
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let links_to_llvm =
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link_name.map_or(false, |val| val.as_str().starts_with("llvm."));
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if links_to_llvm {
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gate_feature_post!(
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&self,
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link_llvm_intrinsics,
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i.span,
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"linking to LLVM intrinsics is experimental"
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);
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}
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}
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ast::ForeignItemKind::TyAlias(..) => {
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gate_feature_post!(&self, extern_types, i.span, "extern types are experimental");
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}
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ast::ForeignItemKind::MacCall(..) => {}
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}
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visit::walk_foreign_item(self, i)
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}
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fn visit_ty(&mut self, ty: &'a ast::Ty) {
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match &ty.kind {
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ast::TyKind::BareFn(bare_fn_ty) => {
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// Function pointers cannot be `const`
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self.check_extern(bare_fn_ty.ext, ast::Const::No);
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self.check_late_bound_lifetime_defs(&bare_fn_ty.generic_params);
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}
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ast::TyKind::Never => {
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gate_feature_post!(&self, never_type, ty.span, "the `!` type is experimental");
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}
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_ => {}
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}
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visit::walk_ty(self, ty)
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}
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fn visit_generics(&mut self, g: &'a ast::Generics) {
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for predicate in &g.where_clause.predicates {
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match predicate {
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ast::WherePredicate::BoundPredicate(bound_pred) => {
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// A type binding, eg `for<'c> Foo: Send+Clone+'c`
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self.check_late_bound_lifetime_defs(&bound_pred.bound_generic_params);
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}
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_ => {}
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}
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}
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visit::walk_generics(self, g);
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}
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fn visit_fn_ret_ty(&mut self, ret_ty: &'a ast::FnRetTy) {
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if let ast::FnRetTy::Ty(output_ty) = ret_ty {
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if let ast::TyKind::Never = output_ty.kind {
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// Do nothing.
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} else {
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self.visit_ty(output_ty)
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}
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}
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}
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fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
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if let ast::StmtKind::Semi(expr) = &stmt.kind
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&& let ast::ExprKind::Assign(lhs, _, _) = &expr.kind
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&& let ast::ExprKind::Type(..) = lhs.kind
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&& self.sess.parse_sess.span_diagnostic.err_count() == 0
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&& !self.features.type_ascription
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&& !lhs.span.allows_unstable(sym::type_ascription)
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{
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// When we encounter a statement of the form `foo: Ty = val;`, this will emit a type
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// ascription error, but the likely intention was to write a `let` statement. (#78907).
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feature_err(
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&self.sess.parse_sess,
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sym::type_ascription,
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lhs.span,
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"type ascription is experimental",
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).span_suggestion_verbose(
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lhs.span.shrink_to_lo(),
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"you might have meant to introduce a new binding",
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"let ",
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Applicability::MachineApplicable,
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).emit();
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}
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visit::walk_stmt(self, stmt);
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}
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fn visit_expr(&mut self, e: &'a ast::Expr) {
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match e.kind {
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ast::ExprKind::Type(..) => {
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if self.sess.parse_sess.span_diagnostic.err_count() == 0 {
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// To avoid noise about type ascription in common syntax errors,
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// only emit if it is the *only* error.
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gate_feature_post!(
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&self,
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type_ascription,
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e.span,
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"type ascription is experimental"
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);
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} else {
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// And if it isn't, cancel the early-pass warning.
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self.sess
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.parse_sess
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.span_diagnostic
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.steal_diagnostic(e.span, StashKey::EarlySyntaxWarning)
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.map(|err| err.cancel());
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}
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}
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ast::ExprKind::TryBlock(_) => {
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gate_feature_post!(&self, try_blocks, e.span, "`try` expression is experimental");
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}
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_ => {}
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}
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visit::walk_expr(self, e)
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}
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fn visit_pat(&mut self, pattern: &'a ast::Pat) {
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match &pattern.kind {
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PatKind::Slice(pats) => {
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for pat in pats {
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|
let inner_pat = match &pat.kind {
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|
PatKind::Ident(.., Some(pat)) => pat,
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_ => pat,
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};
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if let PatKind::Range(Some(_), None, Spanned { .. }) = inner_pat.kind {
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|
gate_feature_post!(
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&self,
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half_open_range_patterns_in_slices,
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pat.span,
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"`X..` patterns in slices are experimental"
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);
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}
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}
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}
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|
PatKind::Box(..) => {
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gate_feature_post!(
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&self,
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box_patterns,
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pattern.span,
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"box pattern syntax is experimental"
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);
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}
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PatKind::Range(_, Some(_), Spanned { node: RangeEnd::Excluded, .. }) => {
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gate_feature_post!(
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&self,
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exclusive_range_pattern,
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pattern.span,
|
|
"exclusive range pattern syntax is experimental"
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);
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}
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|
_ => {}
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}
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visit::walk_pat(self, pattern)
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}
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fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef) {
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self.check_late_bound_lifetime_defs(&t.bound_generic_params);
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visit::walk_poly_trait_ref(self, t);
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}
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fn visit_fn(&mut self, fn_kind: FnKind<'a>, span: Span, _: NodeId) {
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|
if let Some(header) = fn_kind.header() {
|
|
// Stability of const fn methods are covered in `visit_assoc_item` below.
|
|
self.check_extern(header.ext, header.constness);
|
|
}
|
|
|
|
if let FnKind::Closure(ast::ClosureBinder::For { generic_params, .. }, ..) = fn_kind {
|
|
self.check_late_bound_lifetime_defs(generic_params);
|
|
}
|
|
|
|
if fn_kind.ctxt() != Some(FnCtxt::Foreign) && fn_kind.decl().c_variadic() {
|
|
gate_feature_post!(&self, c_variadic, span, "C-variadic functions are unstable");
|
|
}
|
|
|
|
visit::walk_fn(self, fn_kind)
|
|
}
|
|
|
|
fn visit_assoc_constraint(&mut self, constraint: &'a AssocConstraint) {
|
|
if let AssocConstraintKind::Bound { .. } = constraint.kind {
|
|
gate_feature_post!(
|
|
&self,
|
|
associated_type_bounds,
|
|
constraint.span,
|
|
"associated type bounds are unstable"
|
|
)
|
|
}
|
|
visit::walk_assoc_constraint(self, constraint)
|
|
}
|
|
|
|
fn visit_assoc_item(&mut self, i: &'a ast::AssocItem, ctxt: AssocCtxt) {
|
|
let is_fn = match &i.kind {
|
|
ast::AssocItemKind::Fn(_) => true,
|
|
ast::AssocItemKind::Type(box ast::TyAlias { ty, .. }) => {
|
|
if let (Some(_), AssocCtxt::Trait) = (ty, ctxt) {
|
|
gate_feature_post!(
|
|
&self,
|
|
associated_type_defaults,
|
|
i.span,
|
|
"associated type defaults are unstable"
|
|
);
|
|
}
|
|
if let Some(ty) = ty {
|
|
self.check_impl_trait(ty);
|
|
}
|
|
false
|
|
}
|
|
_ => false,
|
|
};
|
|
if let ast::Defaultness::Default(_) = i.kind.defaultness() {
|
|
// Limit `min_specialization` to only specializing functions.
|
|
gate_feature_fn!(
|
|
&self,
|
|
|x: &Features| x.specialization || (is_fn && x.min_specialization),
|
|
i.span,
|
|
sym::specialization,
|
|
"specialization is unstable"
|
|
);
|
|
}
|
|
visit::walk_assoc_item(self, i, ctxt)
|
|
}
|
|
}
|
|
|
|
pub fn check_crate(krate: &ast::Crate, sess: &Session) {
|
|
maybe_stage_features(sess, krate);
|
|
check_incompatible_features(sess);
|
|
let mut visitor = PostExpansionVisitor { sess, features: &sess.features_untracked() };
|
|
|
|
let spans = sess.parse_sess.gated_spans.spans.borrow();
|
|
macro_rules! gate_all {
|
|
($gate:ident, $msg:literal, $help:literal) => {
|
|
if let Some(spans) = spans.get(&sym::$gate) {
|
|
for span in spans {
|
|
gate_feature_post!(&visitor, $gate, *span, $msg, $help);
|
|
}
|
|
}
|
|
};
|
|
($gate:ident, $msg:literal) => {
|
|
if let Some(spans) = spans.get(&sym::$gate) {
|
|
for span in spans {
|
|
gate_feature_post!(&visitor, $gate, *span, $msg);
|
|
}
|
|
}
|
|
};
|
|
}
|
|
gate_all!(
|
|
if_let_guard,
|
|
"`if let` guards are experimental",
|
|
"you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`"
|
|
);
|
|
gate_all!(let_chains, "`let` expressions in this position are unstable");
|
|
gate_all!(
|
|
async_closure,
|
|
"async closures are unstable",
|
|
"to use an async block, remove the `||`: `async {`"
|
|
);
|
|
gate_all!(
|
|
closure_lifetime_binder,
|
|
"`for<...>` binders for closures are experimental",
|
|
"consider removing `for<...>`"
|
|
);
|
|
gate_all!(more_qualified_paths, "usage of qualified paths in this context is experimental");
|
|
gate_all!(generators, "yield syntax is experimental");
|
|
gate_all!(raw_ref_op, "raw address of syntax is experimental");
|
|
gate_all!(const_trait_impl, "const trait impls are experimental");
|
|
gate_all!(
|
|
half_open_range_patterns_in_slices,
|
|
"half-open range patterns in slices are unstable"
|
|
);
|
|
gate_all!(inline_const, "inline-const is experimental");
|
|
gate_all!(inline_const_pat, "inline-const in pattern position is experimental");
|
|
gate_all!(associated_const_equality, "associated const equality is incomplete");
|
|
gate_all!(yeet_expr, "`do yeet` expression is experimental");
|
|
gate_all!(dyn_star, "`dyn*` trait objects are experimental");
|
|
gate_all!(const_closures, "const closures are experimental");
|
|
|
|
// All uses of `gate_all!` below this point were added in #65742,
|
|
// and subsequently disabled (with the non-early gating readded).
|
|
// We emit an early future-incompatible warning for these.
|
|
// New syntax gates should go above here to get a hard error gate.
|
|
macro_rules! gate_all {
|
|
($gate:ident, $msg:literal) => {
|
|
for span in spans.get(&sym::$gate).unwrap_or(&vec![]) {
|
|
gate_feature_post!(future_incompatible; &visitor, $gate, *span, $msg);
|
|
}
|
|
};
|
|
}
|
|
|
|
gate_all!(trait_alias, "trait aliases are experimental");
|
|
gate_all!(associated_type_bounds, "associated type bounds are unstable");
|
|
gate_all!(decl_macro, "`macro` is experimental");
|
|
gate_all!(box_patterns, "box pattern syntax is experimental");
|
|
gate_all!(exclusive_range_pattern, "exclusive range pattern syntax is experimental");
|
|
gate_all!(try_blocks, "`try` blocks are unstable");
|
|
gate_all!(type_ascription, "type ascription is experimental");
|
|
|
|
visit::walk_crate(&mut visitor, krate);
|
|
}
|
|
|
|
fn maybe_stage_features(sess: &Session, krate: &ast::Crate) {
|
|
// checks if `#![feature]` has been used to enable any lang feature
|
|
// does not check the same for lib features unless there's at least one
|
|
// declared lang feature
|
|
if !sess.opts.unstable_features.is_nightly_build() {
|
|
let lang_features = &sess.features_untracked().declared_lang_features;
|
|
if lang_features.len() == 0 {
|
|
return;
|
|
}
|
|
for attr in krate.attrs.iter().filter(|attr| attr.has_name(sym::feature)) {
|
|
let mut err = errors::FeatureOnNonNightly {
|
|
span: attr.span,
|
|
channel: option_env!("CFG_RELEASE_CHANNEL").unwrap_or("(unknown)"),
|
|
stable_features: vec![],
|
|
sugg: None,
|
|
};
|
|
|
|
let mut all_stable = true;
|
|
for ident in
|
|
attr.meta_item_list().into_iter().flatten().flat_map(|nested| nested.ident())
|
|
{
|
|
let name = ident.name;
|
|
let stable_since = lang_features
|
|
.iter()
|
|
.flat_map(|&(feature, _, since)| if feature == name { since } else { None })
|
|
.next();
|
|
if let Some(since) = stable_since {
|
|
err.stable_features.push(errors::StableFeature { name, since });
|
|
} else {
|
|
all_stable = false;
|
|
}
|
|
}
|
|
if all_stable {
|
|
err.sugg = Some(attr.span);
|
|
}
|
|
sess.parse_sess.span_diagnostic.emit_err(err);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_incompatible_features(sess: &Session) {
|
|
let features = sess.features_untracked();
|
|
|
|
let declared_features = features
|
|
.declared_lang_features
|
|
.iter()
|
|
.copied()
|
|
.map(|(name, span, _)| (name, span))
|
|
.chain(features.declared_lib_features.iter().copied());
|
|
|
|
for (f1, f2) in rustc_feature::INCOMPATIBLE_FEATURES
|
|
.iter()
|
|
.filter(|&&(f1, f2)| features.enabled(f1) && features.enabled(f2))
|
|
{
|
|
if let Some((f1_name, f1_span)) = declared_features.clone().find(|(name, _)| name == f1) {
|
|
if let Some((f2_name, f2_span)) = declared_features.clone().find(|(name, _)| name == f2)
|
|
{
|
|
let spans = vec![f1_span, f2_span];
|
|
sess.emit_err(errors::IncompatibleFeatures { spans, f1: f1_name, f2: f2_name });
|
|
}
|
|
}
|
|
}
|
|
}
|