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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /compiler/rustc_ast_passes/src/feature_gate.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'compiler/rustc_ast_passes/src/feature_gate.rs')
-rw-r--r-- | compiler/rustc_ast_passes/src/feature_gate.rs | 901 |
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(); + } + } + } +} |