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-rw-r--r--compiler/rustc_ast_passes/src/feature_gate.rs901
1 files changed, 901 insertions, 0 deletions
diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs
new file mode 100644
index 000000000..789eca1f0
--- /dev/null
+++ b/compiler/rustc_ast_passes/src/feature_gate.rs
@@ -0,0 +1,901 @@
+use rustc_ast as ast;
+use rustc_ast::visit::{self, AssocCtxt, FnCtxt, FnKind, Visitor};
+use rustc_ast::{AssocConstraint, AssocConstraintKind, NodeId};
+use rustc_ast::{PatKind, RangeEnd, VariantData};
+use rustc_errors::{struct_span_err, Applicability};
+use rustc_feature::{AttributeGate, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
+use rustc_feature::{Features, GateIssue};
+use rustc_session::parse::{feature_err, feature_err_issue};
+use rustc_session::Session;
+use rustc_span::source_map::Spanned;
+use rustc_span::symbol::sym;
+use rustc_span::Span;
+
+use tracing::debug;
+
+macro_rules! gate_feature_fn {
+ ($visitor: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr, $help: expr) => {{
+ let (visitor, has_feature, span, name, explain, help) =
+ (&*$visitor, $has_feature, $span, $name, $explain, $help);
+ let has_feature: bool = has_feature(visitor.features);
+ debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature);
+ if !has_feature && !span.allows_unstable($name) {
+ feature_err_issue(&visitor.sess.parse_sess, name, span, GateIssue::Language, explain)
+ .help(help)
+ .emit();
+ }
+ }};
+ ($visitor: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr) => {{
+ let (visitor, has_feature, span, name, explain) =
+ (&*$visitor, $has_feature, $span, $name, $explain);
+ let has_feature: bool = has_feature(visitor.features);
+ debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature);
+ if !has_feature && !span.allows_unstable($name) {
+ feature_err_issue(&visitor.sess.parse_sess, name, span, GateIssue::Language, explain)
+ .emit();
+ }
+ }};
+}
+
+macro_rules! gate_feature_post {
+ ($visitor: expr, $feature: ident, $span: expr, $explain: expr, $help: expr) => {
+ gate_feature_fn!($visitor, |x: &Features| x.$feature, $span, sym::$feature, $explain, $help)
+ };
+ ($visitor: expr, $feature: ident, $span: expr, $explain: expr) => {
+ gate_feature_fn!($visitor, |x: &Features| x.$feature, $span, sym::$feature, $explain)
+ };
+}
+
+pub fn check_attribute(attr: &ast::Attribute, sess: &Session, features: &Features) {
+ PostExpansionVisitor { sess, features }.visit_attribute(attr)
+}
+
+struct PostExpansionVisitor<'a> {
+ sess: &'a Session,
+
+ // `sess` contains a `Features`, but this might not be that one.
+ features: &'a Features,
+}
+
+impl<'a> PostExpansionVisitor<'a> {
+ fn check_abi(&self, abi: ast::StrLit, constness: ast::Const) {
+ let ast::StrLit { symbol_unescaped, span, .. } = abi;
+
+ if let ast::Const::Yes(_) = constness {
+ match symbol_unescaped {
+ // Stable
+ sym::Rust | sym::C => {}
+ abi => gate_feature_post!(
+ &self,
+ const_extern_fn,
+ span,
+ &format!("`{}` as a `const fn` ABI is unstable", abi)
+ ),
+ }
+ }
+
+ match symbol_unescaped.as_str() {
+ // Stable
+ "Rust" | "C" | "cdecl" | "stdcall" | "fastcall" | "aapcs" | "win64" | "sysv64"
+ | "system" => {}
+ "rust-intrinsic" => {
+ gate_feature_post!(&self, intrinsics, span, "intrinsics are subject to change");
+ }
+ "platform-intrinsic" => {
+ gate_feature_post!(
+ &self,
+ platform_intrinsics,
+ span,
+ "platform intrinsics are experimental and possibly buggy"
+ );
+ }
+ "vectorcall" => {
+ gate_feature_post!(
+ &self,
+ abi_vectorcall,
+ span,
+ "vectorcall is experimental and subject to change"
+ );
+ }
+ "thiscall" => {
+ gate_feature_post!(
+ &self,
+ abi_thiscall,
+ span,
+ "thiscall is experimental and subject to change"
+ );
+ }
+ "rust-call" => {
+ gate_feature_post!(
+ &self,
+ unboxed_closures,
+ span,
+ "rust-call ABI is subject to change"
+ );
+ }
+ "rust-cold" => {
+ gate_feature_post!(
+ &self,
+ rust_cold_cc,
+ span,
+ "rust-cold is experimental and subject to change"
+ );
+ }
+ "ptx-kernel" => {
+ gate_feature_post!(
+ &self,
+ abi_ptx,
+ span,
+ "PTX ABIs are experimental and subject to change"
+ );
+ }
+ "unadjusted" => {
+ gate_feature_post!(
+ &self,
+ abi_unadjusted,
+ span,
+ "unadjusted ABI is an implementation detail and perma-unstable"
+ );
+ }
+ "msp430-interrupt" => {
+ gate_feature_post!(
+ &self,
+ abi_msp430_interrupt,
+ span,
+ "msp430-interrupt ABI is experimental and subject to change"
+ );
+ }
+ "x86-interrupt" => {
+ gate_feature_post!(
+ &self,
+ abi_x86_interrupt,
+ span,
+ "x86-interrupt ABI is experimental and subject to change"
+ );
+ }
+ "amdgpu-kernel" => {
+ gate_feature_post!(
+ &self,
+ abi_amdgpu_kernel,
+ span,
+ "amdgpu-kernel ABI is experimental and subject to change"
+ );
+ }
+ "avr-interrupt" | "avr-non-blocking-interrupt" => {
+ gate_feature_post!(
+ &self,
+ abi_avr_interrupt,
+ span,
+ "avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change"
+ );
+ }
+ "efiapi" => {
+ gate_feature_post!(
+ &self,
+ abi_efiapi,
+ span,
+ "efiapi ABI is experimental and subject to change"
+ );
+ }
+ "C-cmse-nonsecure-call" => {
+ gate_feature_post!(
+ &self,
+ abi_c_cmse_nonsecure_call,
+ span,
+ "C-cmse-nonsecure-call ABI is experimental and subject to change"
+ );
+ }
+ "C-unwind" => {
+ gate_feature_post!(
+ &self,
+ c_unwind,
+ span,
+ "C-unwind ABI is experimental and subject to change"
+ );
+ }
+ "stdcall-unwind" => {
+ gate_feature_post!(
+ &self,
+ c_unwind,
+ span,
+ "stdcall-unwind ABI is experimental and subject to change"
+ );
+ }
+ "system-unwind" => {
+ gate_feature_post!(
+ &self,
+ c_unwind,
+ span,
+ "system-unwind ABI is experimental and subject to change"
+ );
+ }
+ "thiscall-unwind" => {
+ gate_feature_post!(
+ &self,
+ c_unwind,
+ span,
+ "thiscall-unwind ABI is experimental and subject to change"
+ );
+ }
+ "cdecl-unwind" => {
+ gate_feature_post!(
+ &self,
+ c_unwind,
+ span,
+ "cdecl-unwind ABI is experimental and subject to change"
+ );
+ }
+ "fastcall-unwind" => {
+ gate_feature_post!(
+ &self,
+ c_unwind,
+ span,
+ "fastcall-unwind ABI is experimental and subject to change"
+ );
+ }
+ "vectorcall-unwind" => {
+ gate_feature_post!(
+ &self,
+ c_unwind,
+ span,
+ "vectorcall-unwind ABI is experimental and subject to change"
+ );
+ }
+ "aapcs-unwind" => {
+ gate_feature_post!(
+ &self,
+ c_unwind,
+ span,
+ "aapcs-unwind ABI is experimental and subject to change"
+ );
+ }
+ "win64-unwind" => {
+ gate_feature_post!(
+ &self,
+ c_unwind,
+ span,
+ "win64-unwind ABI is experimental and subject to change"
+ );
+ }
+ "sysv64-unwind" => {
+ gate_feature_post!(
+ &self,
+ c_unwind,
+ span,
+ "sysv64-unwind ABI is experimental and subject to change"
+ );
+ }
+ "wasm" => {
+ gate_feature_post!(
+ &self,
+ wasm_abi,
+ span,
+ "wasm ABI is experimental and subject to change"
+ );
+ }
+ abi => {
+ if self.sess.opts.pretty.map_or(true, |ppm| ppm.needs_hir()) {
+ self.sess.parse_sess.span_diagnostic.delay_span_bug(
+ span,
+ &format!("unrecognized ABI not caught in lowering: {}", abi),
+ );
+ }
+ }
+ }
+ }
+
+ fn check_extern(&self, ext: ast::Extern, constness: ast::Const) {
+ if let ast::Extern::Explicit(abi, _) = ext {
+ self.check_abi(abi, constness);
+ }
+ }
+
+ fn maybe_report_invalid_custom_discriminants(&self, variants: &[ast::Variant]) {
+ let has_fields = variants.iter().any(|variant| match variant.data {
+ VariantData::Tuple(..) | VariantData::Struct(..) => true,
+ VariantData::Unit(..) => false,
+ });
+
+ let discriminant_spans = variants
+ .iter()
+ .filter(|variant| match variant.data {
+ VariantData::Tuple(..) | VariantData::Struct(..) => false,
+ VariantData::Unit(..) => true,
+ })
+ .filter_map(|variant| variant.disr_expr.as_ref().map(|c| c.value.span))
+ .collect::<Vec<_>>();
+
+ if !discriminant_spans.is_empty() && has_fields {
+ let mut err = feature_err(
+ &self.sess.parse_sess,
+ sym::arbitrary_enum_discriminant,
+ discriminant_spans.clone(),
+ "custom discriminant values are not allowed in enums with tuple or struct variants",
+ );
+ for sp in discriminant_spans {
+ err.span_label(sp, "disallowed custom discriminant");
+ }
+ for variant in variants.iter() {
+ match &variant.data {
+ VariantData::Struct(..) => {
+ err.span_label(variant.span, "struct variant defined here");
+ }
+ VariantData::Tuple(..) => {
+ err.span_label(variant.span, "tuple variant defined here");
+ }
+ VariantData::Unit(..) => {}
+ }
+ }
+ err.emit();
+ }
+ }
+
+ fn check_gat(&self, generics: &ast::Generics, span: Span) {
+ if !generics.params.is_empty() {
+ gate_feature_post!(
+ &self,
+ generic_associated_types,
+ span,
+ "generic associated types are unstable"
+ );
+ }
+ if !generics.where_clause.predicates.is_empty() {
+ gate_feature_post!(
+ &self,
+ generic_associated_types,
+ span,
+ "where clauses on associated types are unstable"
+ );
+ }
+ }
+
+ /// Feature gate `impl Trait` inside `type Alias = $type_expr;`.
+ fn check_impl_trait(&self, ty: &ast::Ty) {
+ struct ImplTraitVisitor<'a> {
+ vis: &'a PostExpansionVisitor<'a>,
+ }
+ impl Visitor<'_> for ImplTraitVisitor<'_> {
+ fn visit_ty(&mut self, ty: &ast::Ty) {
+ if let ast::TyKind::ImplTrait(..) = ty.kind {
+ gate_feature_post!(
+ &self.vis,
+ type_alias_impl_trait,
+ ty.span,
+ "`impl Trait` in type aliases is unstable"
+ );
+ }
+ visit::walk_ty(self, ty);
+ }
+ }
+ ImplTraitVisitor { vis: self }.visit_ty(ty);
+ }
+}
+
+impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
+ fn visit_attribute(&mut self, attr: &ast::Attribute) {
+ let attr_info = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name));
+ // Check feature gates for built-in attributes.
+ if let Some(BuiltinAttribute {
+ gate: AttributeGate::Gated(_, name, descr, has_feature),
+ ..
+ }) = attr_info
+ {
+ gate_feature_fn!(self, has_feature, attr.span, *name, descr);
+ }
+ // Check unstable flavors of the `#[doc]` attribute.
+ if attr.has_name(sym::doc) {
+ for nested_meta in attr.meta_item_list().unwrap_or_default() {
+ macro_rules! gate_doc { ($($name:ident => $feature:ident)*) => {
+ $(if nested_meta.has_name(sym::$name) {
+ let msg = concat!("`#[doc(", stringify!($name), ")]` is experimental");
+ gate_feature_post!(self, $feature, attr.span, msg);
+ })*
+ }}
+
+ gate_doc!(
+ cfg => doc_cfg
+ cfg_hide => doc_cfg_hide
+ masked => doc_masked
+ notable_trait => doc_notable_trait
+ );
+
+ if nested_meta.has_name(sym::keyword) {
+ let msg = "`#[doc(keyword)]` is meant for internal use only";
+ gate_feature_post!(self, rustdoc_internals, attr.span, msg);
+ }
+
+ if nested_meta.has_name(sym::fake_variadic) {
+ let msg = "`#[doc(fake_variadic)]` is meant for internal use only";
+ gate_feature_post!(self, rustdoc_internals, attr.span, msg);
+ }
+ }
+ }
+
+ // Emit errors for non-staged-api crates.
+ if !self.features.staged_api {
+ if attr.has_name(sym::unstable)
+ || attr.has_name(sym::stable)
+ || attr.has_name(sym::rustc_const_unstable)
+ || attr.has_name(sym::rustc_const_stable)
+ {
+ struct_span_err!(
+ self.sess,
+ attr.span,
+ E0734,
+ "stability attributes may not be used outside of the standard library",
+ )
+ .emit();
+ }
+ }
+ }
+
+ fn visit_item(&mut self, i: &'a ast::Item) {
+ match i.kind {
+ ast::ItemKind::ForeignMod(ref foreign_module) => {
+ if let Some(abi) = foreign_module.abi {
+ self.check_abi(abi, ast::Const::No);
+ }
+ }
+
+ ast::ItemKind::Fn(..) => {
+ if self.sess.contains_name(&i.attrs, sym::start) {
+ gate_feature_post!(
+ &self,
+ start,
+ i.span,
+ "`#[start]` functions are experimental \
+ and their signature may change \
+ over time"
+ );
+ }
+ }
+
+ ast::ItemKind::Struct(..) => {
+ for attr in self.sess.filter_by_name(&i.attrs, sym::repr) {
+ for item in attr.meta_item_list().unwrap_or_else(Vec::new) {
+ if item.has_name(sym::simd) {
+ gate_feature_post!(
+ &self,
+ repr_simd,
+ attr.span,
+ "SIMD types are experimental and possibly buggy"
+ );
+ }
+ }
+ }
+ }
+
+ ast::ItemKind::Enum(ast::EnumDef { ref variants, .. }, ..) => {
+ for variant in variants {
+ match (&variant.data, &variant.disr_expr) {
+ (ast::VariantData::Unit(..), _) => {}
+ (_, Some(disr_expr)) => gate_feature_post!(
+ &self,
+ arbitrary_enum_discriminant,
+ disr_expr.value.span,
+ "discriminants on non-unit variants are experimental"
+ ),
+ _ => {}
+ }
+ }
+
+ let has_feature = self.features.arbitrary_enum_discriminant;
+ if !has_feature && !i.span.allows_unstable(sym::arbitrary_enum_discriminant) {
+ self.maybe_report_invalid_custom_discriminants(&variants);
+ }
+ }
+
+ ast::ItemKind::Impl(box ast::Impl { polarity, defaultness, ref of_trait, .. }) => {
+ if let ast::ImplPolarity::Negative(span) = polarity {
+ gate_feature_post!(
+ &self,
+ negative_impls,
+ span.to(of_trait.as_ref().map_or(span, |t| t.path.span)),
+ "negative trait bounds are not yet fully implemented; \
+ use marker types for now"
+ );
+ }
+
+ if let ast::Defaultness::Default(_) = defaultness {
+ gate_feature_post!(&self, specialization, i.span, "specialization is unstable");
+ }
+ }
+
+ ast::ItemKind::Trait(box ast::Trait { is_auto: ast::IsAuto::Yes, .. }) => {
+ gate_feature_post!(
+ &self,
+ auto_traits,
+ i.span,
+ "auto traits are experimental and possibly buggy"
+ );
+ }
+
+ ast::ItemKind::TraitAlias(..) => {
+ gate_feature_post!(&self, trait_alias, i.span, "trait aliases are experimental");
+ }
+
+ ast::ItemKind::MacroDef(ast::MacroDef { macro_rules: false, .. }) => {
+ let msg = "`macro` is experimental";
+ gate_feature_post!(&self, decl_macro, i.span, msg);
+ }
+
+ ast::ItemKind::TyAlias(box ast::TyAlias { ty: Some(ref ty), .. }) => {
+ self.check_impl_trait(&ty)
+ }
+
+ _ => {}
+ }
+
+ visit::walk_item(self, i);
+ }
+
+ fn visit_foreign_item(&mut self, i: &'a ast::ForeignItem) {
+ match i.kind {
+ ast::ForeignItemKind::Fn(..) | ast::ForeignItemKind::Static(..) => {
+ let link_name = self.sess.first_attr_value_str_by_name(&i.attrs, sym::link_name);
+ let links_to_llvm =
+ link_name.map_or(false, |val| val.as_str().starts_with("llvm."));
+ if links_to_llvm {
+ gate_feature_post!(
+ &self,
+ link_llvm_intrinsics,
+ i.span,
+ "linking to LLVM intrinsics is experimental"
+ );
+ }
+ }
+ ast::ForeignItemKind::TyAlias(..) => {
+ gate_feature_post!(&self, extern_types, i.span, "extern types are experimental");
+ }
+ ast::ForeignItemKind::MacCall(..) => {}
+ }
+
+ visit::walk_foreign_item(self, i)
+ }
+
+ fn visit_ty(&mut self, ty: &'a ast::Ty) {
+ match ty.kind {
+ ast::TyKind::BareFn(ref bare_fn_ty) => {
+ // Function pointers cannot be `const`
+ self.check_extern(bare_fn_ty.ext, ast::Const::No);
+ }
+ ast::TyKind::Never => {
+ gate_feature_post!(&self, never_type, ty.span, "the `!` type is experimental");
+ }
+ _ => {}
+ }
+ visit::walk_ty(self, ty)
+ }
+
+ fn visit_fn_ret_ty(&mut self, ret_ty: &'a ast::FnRetTy) {
+ if let ast::FnRetTy::Ty(ref output_ty) = *ret_ty {
+ if let ast::TyKind::Never = output_ty.kind {
+ // Do nothing.
+ } else {
+ self.visit_ty(output_ty)
+ }
+ }
+ }
+
+ fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
+ if let ast::StmtKind::Semi(expr) = &stmt.kind
+ && let ast::ExprKind::Assign(lhs, _, _) = &expr.kind
+ && let ast::ExprKind::Type(..) = lhs.kind
+ && self.sess.parse_sess.span_diagnostic.err_count() == 0
+ && !self.features.type_ascription
+ && !lhs.span.allows_unstable(sym::type_ascription)
+ {
+ // When we encounter a statement of the form `foo: Ty = val;`, this will emit a type
+ // ascription error, but the likely intention was to write a `let` statement. (#78907).
+ feature_err_issue(
+ &self.sess.parse_sess,
+ sym::type_ascription,
+ lhs.span,
+ GateIssue::Language,
+ "type ascription is experimental",
+ ).span_suggestion_verbose(
+ lhs.span.shrink_to_lo(),
+ "you might have meant to introduce a new binding",
+ "let ".to_string(),
+ Applicability::MachineApplicable,
+ ).emit();
+ }
+ visit::walk_stmt(self, stmt);
+ }
+
+ fn visit_expr(&mut self, e: &'a ast::Expr) {
+ match e.kind {
+ ast::ExprKind::Box(_) => {
+ gate_feature_post!(
+ &self,
+ box_syntax,
+ e.span,
+ "box expression syntax is experimental; you can call `Box::new` instead"
+ );
+ }
+ ast::ExprKind::Type(..) => {
+ // To avoid noise about type ascription in common syntax errors, only emit if it
+ // is the *only* error.
+ if self.sess.parse_sess.span_diagnostic.err_count() == 0 {
+ gate_feature_post!(
+ &self,
+ type_ascription,
+ e.span,
+ "type ascription is experimental"
+ );
+ }
+ }
+ ast::ExprKind::TryBlock(_) => {
+ gate_feature_post!(&self, try_blocks, e.span, "`try` expression is experimental");
+ }
+ ast::ExprKind::Block(_, Some(label)) => {
+ gate_feature_post!(
+ &self,
+ label_break_value,
+ label.ident.span,
+ "labels on blocks are unstable"
+ );
+ }
+ _ => {}
+ }
+ visit::walk_expr(self, e)
+ }
+
+ fn visit_pat(&mut self, pattern: &'a ast::Pat) {
+ match &pattern.kind {
+ PatKind::Slice(pats) => {
+ for pat in pats {
+ let inner_pat = match &pat.kind {
+ PatKind::Ident(.., Some(pat)) => pat,
+ _ => pat,
+ };
+ if let PatKind::Range(Some(_), None, Spanned { .. }) = inner_pat.kind {
+ gate_feature_post!(
+ &self,
+ half_open_range_patterns,
+ pat.span,
+ "`X..` patterns in slices are experimental"
+ );
+ }
+ }
+ }
+ PatKind::Box(..) => {
+ gate_feature_post!(
+ &self,
+ box_patterns,
+ pattern.span,
+ "box pattern syntax is experimental"
+ );
+ }
+ PatKind::Range(_, Some(_), Spanned { node: RangeEnd::Excluded, .. }) => {
+ gate_feature_post!(
+ &self,
+ exclusive_range_pattern,
+ pattern.span,
+ "exclusive range pattern syntax is experimental"
+ );
+ }
+ _ => {}
+ }
+ visit::walk_pat(self, pattern)
+ }
+
+ fn visit_fn(&mut self, fn_kind: FnKind<'a>, span: Span, _: NodeId) {
+ 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 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, span)
+ }
+
+ 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::TyAlias(box ast::TyAlias { ref generics, ref 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);
+ }
+ self.check_gat(generics, i.span);
+ 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, $msg);
+ }
+ }
+ };
+ }
+ gate_all!(
+ if_let_guard,
+ "`if let` guards are experimental",
+ "you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`"
+ );
+ gate_all!(let_chains, "`let` expressions in this position are unstable");
+ gate_all!(
+ async_closure,
+ "async closures are unstable",
+ "to use an async block, remove the `||`: `async {`"
+ );
+ gate_all!(
+ closure_lifetime_binder,
+ "`for<...>` binders for closures are experimental",
+ "consider removing `for<...>`"
+ );
+ gate_all!(more_qualified_paths, "usage of qualified paths in this context is experimental");
+ gate_all!(generators, "yield syntax is experimental");
+ gate_all!(raw_ref_op, "raw address of syntax is experimental");
+ gate_all!(const_trait_impl, "const trait impls are experimental");
+ gate_all!(half_open_range_patterns, "half-open range patterns are unstable");
+ gate_all!(inline_const, "inline-const is experimental");
+ gate_all!(inline_const_pat, "inline-const in pattern position is experimental");
+ gate_all!(associated_const_equality, "associated const equality is incomplete");
+ gate_all!(yeet_expr, "`do yeet` expression is experimental");
+
+ // All uses of `gate_all!` below this point were added in #65742,
+ // and subsequently disabled (with the non-early gating readded).
+ macro_rules! gate_all {
+ ($gate:ident, $msg:literal) => {
+ // FIXME(eddyb) do something more useful than always
+ // disabling these uses of early feature-gatings.
+ if false {
+ for span in spans.get(&sym::$gate).unwrap_or(&vec![]) {
+ gate_feature_post!(&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!(label_break_value, "labels on blocks are unstable");
+ gate_all!(box_syntax, "box expression syntax is experimental; you can call `Box::new` instead");
+ // To avoid noise about type ascription in common syntax errors,
+ // only emit if it is the *only* error. (Also check it last.)
+ if sess.parse_sess.span_diagnostic.err_count() == 0 {
+ 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 = struct_span_err!(
+ sess.parse_sess.span_diagnostic,
+ attr.span,
+ E0554,
+ "`#![feature]` may not be used on the {} release channel",
+ option_env!("CFG_RELEASE_CHANNEL").unwrap_or("(unknown)")
+ );
+ 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.help(&format!(
+ "the feature `{}` has been stable since {} and no longer requires \
+ an attribute to enable",
+ name, since
+ ));
+ } else {
+ all_stable = false;
+ }
+ }
+ if all_stable {
+ err.span_suggestion(
+ attr.span,
+ "remove the attribute",
+ "",
+ Applicability::MachineApplicable,
+ );
+ }
+ err.emit();
+ }
+ }
+}
+
+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.struct_span_err(
+ spans.clone(),
+ &format!(
+ "features `{}` and `{}` are incompatible, using them at the same time \
+ is not allowed",
+ f1_name, f2_name
+ ),
+ )
+ .help("remove one of these features")
+ .emit();
+ }
+ }
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-11 21:27:47 +0000