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use super::{active::{ACTIVE_FEATURES, Features}, Feature, State as FeatureState};
use super::accepted::ACCEPTED_FEATURES;
use super::removed::{REMOVED_FEATURES, STABLE_REMOVED_FEATURES};
use super::builtin_attrs::{AttributeGate, BUILTIN_ATTRIBUTE_MAP};
use crate::ast::{
self, AssocTyConstraint, AssocTyConstraintKind, NodeId, GenericParam, GenericParamKind,
PatKind, RangeEnd,
};
use crate::attr::{self, check_builtin_attribute};
use crate::source_map::Spanned;
use crate::edition::{ALL_EDITIONS, Edition};
use crate::visit::{self, FnKind, Visitor};
use crate::parse::{token, ParseSess};
use crate::parse::parser::Parser;
use crate::symbol::{Symbol, sym};
use crate::tokenstream::TokenTree;
use errors::{Applicability, DiagnosticBuilder, Handler};
use rustc_data_structures::fx::FxHashMap;
use rustc_target::spec::abi::Abi;
use syntax_pos::{Span, DUMMY_SP, MultiSpan};
use log::debug;
use std::env;
#[derive(Copy, Clone, Debug)]
pub enum Stability {
Unstable,
// First argument is tracking issue link; second argument is an optional
// help message, which defaults to "remove this attribute"
Deprecated(&'static str, Option<&'static str>),
}
macro_rules! gate_feature_fn {
($cx: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr, $level: expr) => {{
let (cx, has_feature, span,
name, explain, level) = (&*$cx, $has_feature, $span, $name, $explain, $level);
let has_feature: bool = has_feature(&$cx.features);
debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature);
if !has_feature && !span.allows_unstable($name) {
leveled_feature_err(cx.parse_sess, name, span, GateIssue::Language, explain, level)
.emit();
}
}}
}
macro_rules! gate_feature {
($cx: expr, $feature: ident, $span: expr, $explain: expr) => {
gate_feature_fn!($cx, |x:&Features| x.$feature, $span,
sym::$feature, $explain, GateStrength::Hard)
};
($cx: expr, $feature: ident, $span: expr, $explain: expr, $level: expr) => {
gate_feature_fn!($cx, |x:&Features| x.$feature, $span,
sym::$feature, $explain, $level)
};
}
crate fn check_attribute(attr: &ast::Attribute, parse_sess: &ParseSess, features: &Features) {
PostExpansionVisitor { parse_sess, features }.visit_attribute(attr)
}
fn find_lang_feature_issue(feature: Symbol) -> Option<u32> {
if let Some(info) = ACTIVE_FEATURES.iter().find(|t| t.name == feature) {
// FIXME (#28244): enforce that active features have issue numbers
// assert!(info.issue.is_some())
info.issue
} else {
// search in Accepted, Removed, or Stable Removed features
let found = ACCEPTED_FEATURES.iter().chain(REMOVED_FEATURES).chain(STABLE_REMOVED_FEATURES)
.find(|t| t.name == feature);
match found {
Some(&Feature { issue, .. }) => issue,
None => panic!("Feature `{}` is not declared anywhere", feature),
}
}
}
pub enum GateIssue {
Language,
Library(Option<u32>)
}
#[derive(Debug, Copy, Clone, PartialEq)]
pub enum GateStrength {
/// A hard error. (Most feature gates should use this.)
Hard,
/// Only a warning. (Use this only as backwards-compatibility demands.)
Soft,
}
pub fn emit_feature_err(
sess: &ParseSess,
feature: Symbol,
span: Span,
issue: GateIssue,
explain: &str,
) {
feature_err(sess, feature, span, issue, explain).emit();
}
pub fn feature_err<'a, S: Into<MultiSpan>>(
sess: &'a ParseSess,
feature: Symbol,
span: S,
issue: GateIssue,
explain: &str,
) -> DiagnosticBuilder<'a> {
leveled_feature_err(sess, feature, span, issue, explain, GateStrength::Hard)
}
fn leveled_feature_err<'a, S: Into<MultiSpan>>(
sess: &'a ParseSess,
feature: Symbol,
span: S,
issue: GateIssue,
explain: &str,
level: GateStrength,
) -> DiagnosticBuilder<'a> {
let diag = &sess.span_diagnostic;
let issue = match issue {
GateIssue::Language => find_lang_feature_issue(feature),
GateIssue::Library(lib) => lib,
};
let mut err = match level {
GateStrength::Hard => {
diag.struct_span_err_with_code(span, explain, stringify_error_code!(E0658))
}
GateStrength::Soft => diag.struct_span_warn(span, explain),
};
match issue {
None | Some(0) => {} // We still accept `0` as a stand-in for backwards compatibility
Some(n) => {
err.note(&format!(
"for more information, see https://github.com/rust-lang/rust/issues/{}",
n,
));
}
}
// #23973: do not suggest `#![feature(...)]` if we are in beta/stable
if sess.unstable_features.is_nightly_build() {
err.help(&format!("add `#![feature({})]` to the crate attributes to enable", feature));
}
// If we're on stable and only emitting a "soft" warning, add a note to
// clarify that the feature isn't "on" (rather than being on but
// warning-worthy).
if !sess.unstable_features.is_nightly_build() && level == GateStrength::Soft {
err.help("a nightly build of the compiler is required to enable this feature");
}
err
}
const EXPLAIN_BOX_SYNTAX: &str =
"box expression syntax is experimental; you can call `Box::new` instead";
pub const EXPLAIN_STMT_ATTR_SYNTAX: &str =
"attributes on expressions are experimental";
pub const EXPLAIN_ALLOW_INTERNAL_UNSTABLE: &str =
"allow_internal_unstable side-steps feature gating and stability checks";
pub const EXPLAIN_ALLOW_INTERNAL_UNSAFE: &str =
"allow_internal_unsafe side-steps the unsafe_code lint";
pub const EXPLAIN_UNSIZED_TUPLE_COERCION: &str =
"unsized tuple coercion is not stable enough for use and is subject to change";
struct PostExpansionVisitor<'a> {
parse_sess: &'a ParseSess,
features: &'a Features,
}
macro_rules! gate_feature_post {
($cx: expr, $feature: ident, $span: expr, $explain: expr) => {{
let (cx, span) = ($cx, $span);
if !span.allows_unstable(sym::$feature) {
gate_feature!(cx, $feature, span, $explain)
}
}};
($cx: expr, $feature: ident, $span: expr, $explain: expr, $level: expr) => {{
let (cx, span) = ($cx, $span);
if !span.allows_unstable(sym::$feature) {
gate_feature!(cx, $feature, span, $explain, $level)
}
}}
}
impl<'a> PostExpansionVisitor<'a> {
fn check_abi(&self, abi: Abi, span: Span) {
match abi {
Abi::RustIntrinsic => {
gate_feature_post!(&self, intrinsics, span,
"intrinsics are subject to change");
},
Abi::PlatformIntrinsic => {
gate_feature_post!(&self, platform_intrinsics, span,
"platform intrinsics are experimental and possibly buggy");
},
Abi::Vectorcall => {
gate_feature_post!(&self, abi_vectorcall, span,
"vectorcall is experimental and subject to change");
},
Abi::Thiscall => {
gate_feature_post!(&self, abi_thiscall, span,
"thiscall is experimental and subject to change");
},
Abi::RustCall => {
gate_feature_post!(&self, unboxed_closures, span,
"rust-call ABI is subject to change");
},
Abi::PtxKernel => {
gate_feature_post!(&self, abi_ptx, span,
"PTX ABIs are experimental and subject to change");
},
Abi::Unadjusted => {
gate_feature_post!(&self, abi_unadjusted, span,
"unadjusted ABI is an implementation detail and perma-unstable");
},
Abi::Msp430Interrupt => {
gate_feature_post!(&self, abi_msp430_interrupt, span,
"msp430-interrupt ABI is experimental and subject to change");
},
Abi::X86Interrupt => {
gate_feature_post!(&self, abi_x86_interrupt, span,
"x86-interrupt ABI is experimental and subject to change");
},
Abi::AmdGpuKernel => {
gate_feature_post!(&self, abi_amdgpu_kernel, span,
"amdgpu-kernel ABI is experimental and subject to change");
},
// Stable
Abi::Cdecl |
Abi::Stdcall |
Abi::Fastcall |
Abi::Aapcs |
Abi::Win64 |
Abi::SysV64 |
Abi::Rust |
Abi::C |
Abi::System => {}
}
}
}
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)).map(|a| **a);
// Check feature gates for built-in attributes.
if let Some((.., AttributeGate::Gated(_, name, descr, has_feature))) = attr_info {
gate_feature_fn!(self, has_feature, attr.span, name, descr, GateStrength::Hard);
}
// Check input tokens for built-in and key-value attributes.
match attr_info {
// `rustc_dummy` doesn't have any restrictions specific to built-in attributes.
Some((name, _, template, _)) if name != sym::rustc_dummy =>
check_builtin_attribute(self.parse_sess, attr, name, template),
_ => if let Some(TokenTree::Token(token)) = attr.tokens.trees().next() {
if token == token::Eq {
// All key-value attributes are restricted to meta-item syntax.
attr.parse_meta(self.parse_sess).map_err(|mut err| err.emit()).ok();
}
}
}
// Check unstable flavors of the `#[doc]` attribute.
if attr.check_name(sym::doc) {
for nested_meta in attr.meta_item_list().unwrap_or_default() {
macro_rules! gate_doc { ($($name:ident => $feature:ident)*) => {
$(if nested_meta.check_name(sym::$name) {
let msg = concat!("`#[doc(", stringify!($name), ")]` is experimental");
gate_feature!(self, $feature, attr.span, msg);
})*
}}
gate_doc!(
include => external_doc
cfg => doc_cfg
masked => doc_masked
spotlight => doc_spotlight
alias => doc_alias
keyword => doc_keyword
);
}
}
}
fn visit_name(&mut self, sp: Span, name: ast::Name) {
if !name.as_str().is_ascii() {
gate_feature_post!(
&self,
non_ascii_idents,
self.parse_sess.source_map().def_span(sp),
"non-ascii idents are not fully supported"
);
}
}
fn visit_item(&mut self, i: &'a ast::Item) {
match i.node {
ast::ItemKind::ForeignMod(ref foreign_module) => {
self.check_abi(foreign_module.abi, i.span);
}
ast::ItemKind::Fn(..) => {
if attr::contains_name(&i.attrs[..], sym::plugin_registrar) {
gate_feature_post!(&self, plugin_registrar, i.span,
"compiler plugins are experimental and possibly buggy");
}
if attr::contains_name(&i.attrs[..], sym::start) {
gate_feature_post!(&self, start, i.span,
"a `#[start]` function is an experimental \
feature whose signature may change \
over time");
}
if attr::contains_name(&i.attrs[..], sym::main) {
gate_feature_post!(&self, main, i.span,
"declaration of a non-standard `#[main]` \
function may change over time, for now \
a top-level `fn main()` is required");
}
}
ast::ItemKind::Struct(..) => {
for attr in attr::filter_by_name(&i.attrs[..], sym::repr) {
for item in attr.meta_item_list().unwrap_or_else(Vec::new) {
if item.check_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) {
Parser::maybe_report_invalid_custom_discriminants(self.parse_sess, &variants);
}
}
ast::ItemKind::Impl(_, polarity, defaultness, ..) => {
if polarity == ast::ImplPolarity::Negative {
gate_feature_post!(&self, optin_builtin_traits,
i.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(ast::IsAuto::Yes, ..) => {
gate_feature_post!(&self, optin_builtin_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 { legacy: false, .. }) => {
let msg = "`macro` is experimental";
gate_feature_post!(&self, decl_macro, i.span, msg);
}
ast::ItemKind::OpaqueTy(..) => {
gate_feature_post!(
&self,
type_alias_impl_trait,
i.span,
"`impl Trait` in type aliases is unstable"
);
}
_ => {}
}
visit::walk_item(self, i);
}
fn visit_foreign_item(&mut self, i: &'a ast::ForeignItem) {
match i.node {
ast::ForeignItemKind::Fn(..) |
ast::ForeignItemKind::Static(..) => {
let link_name = attr::first_attr_value_str_by_name(&i.attrs, sym::link_name);
let links_to_llvm = match link_name {
Some(val) => val.as_str().starts_with("llvm."),
_ => false
};
if links_to_llvm {
gate_feature_post!(&self, link_llvm_intrinsics, i.span,
"linking to LLVM intrinsics is experimental");
}
}
ast::ForeignItemKind::Ty => {
gate_feature_post!(&self, extern_types, i.span,
"extern types are experimental");
}
ast::ForeignItemKind::Macro(..) => {}
}
visit::walk_foreign_item(self, i)
}
fn visit_ty(&mut self, ty: &'a ast::Ty) {
match ty.node {
ast::TyKind::BareFn(ref bare_fn_ty) => {
self.check_abi(bare_fn_ty.abi, ty.span);
}
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::FunctionRetTy) {
if let ast::FunctionRetTy::Ty(ref output_ty) = *ret_ty {
if let ast::TyKind::Never = output_ty.node {
// Do nothing.
} else {
self.visit_ty(output_ty)
}
}
}
fn visit_expr(&mut self, e: &'a ast::Expr) {
match e.node {
ast::ExprKind::Box(_) => {
gate_feature_post!(&self, box_syntax, e.span, EXPLAIN_BOX_SYNTAX);
}
ast::ExprKind::Type(..) => {
// To avoid noise about type ascription in common syntax errors, only emit if it
// is the *only* error.
if self.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(_, opt_label) => {
if let Some(label) = opt_label {
gate_feature_post!(&self, label_break_value, label.ident.span,
"labels on blocks are unstable");
}
}
_ => {}
}
visit::walk_expr(self, e)
}
fn visit_arm(&mut self, arm: &'a ast::Arm) {
visit::walk_arm(self, arm)
}
fn visit_pat(&mut self, pattern: &'a ast::Pat) {
match &pattern.node {
PatKind::Slice(pats) => {
for pat in &*pats {
let span = pat.span;
let inner_pat = match &pat.node {
PatKind::Ident(.., Some(pat)) => pat,
_ => pat,
};
if inner_pat.is_rest() {
gate_feature_post!(
&self,
slice_patterns,
span,
"subslice patterns are unstable"
);
}
}
}
PatKind::Box(..) => {
gate_feature_post!(&self, box_patterns,
pattern.span,
"box pattern syntax is experimental");
}
PatKind::Range(_, _, 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>,
fn_decl: &'a ast::FnDecl,
span: Span,
_node_id: NodeId) {
if let Some(header) = fn_kind.header() {
// Stability of const fn methods are covered in
// `visit_trait_item` and `visit_impl_item` below; this is
// because default methods don't pass through this point.
self.check_abi(header.abi, span);
}
if fn_decl.c_variadic {
gate_feature_post!(&self, c_variadic, span, "C-variadic functions are unstable");
}
visit::walk_fn(self, fn_kind, fn_decl, span)
}
fn visit_generic_param(&mut self, param: &'a GenericParam) {
match param.kind {
GenericParamKind::Const { .. } =>
gate_feature_post!(&self, const_generics, param.ident.span,
"const generics are unstable"),
_ => {}
}
visit::walk_generic_param(self, param)
}
fn visit_assoc_ty_constraint(&mut self, constraint: &'a AssocTyConstraint) {
match constraint.kind {
AssocTyConstraintKind::Bound { .. } =>
gate_feature_post!(&self, associated_type_bounds, constraint.span,
"associated type bounds are unstable"),
_ => {}
}
visit::walk_assoc_ty_constraint(self, constraint)
}
fn visit_trait_item(&mut self, ti: &'a ast::TraitItem) {
match ti.node {
ast::TraitItemKind::Method(ref sig, ref block) => {
if block.is_none() {
self.check_abi(sig.header.abi, ti.span);
}
if sig.decl.c_variadic {
gate_feature_post!(&self, c_variadic, ti.span,
"C-variadic functions are unstable");
}
if sig.header.constness.node == ast::Constness::Const {
gate_feature_post!(&self, const_fn, ti.span, "const fn is unstable");
}
}
ast::TraitItemKind::Type(_, ref default) => {
// We use three if statements instead of something like match guards so that all
// of these errors can be emitted if all cases apply.
if default.is_some() {
gate_feature_post!(&self, associated_type_defaults, ti.span,
"associated type defaults are unstable");
}
if !ti.generics.params.is_empty() {
gate_feature_post!(&self, generic_associated_types, ti.span,
"generic associated types are unstable");
}
if !ti.generics.where_clause.predicates.is_empty() {
gate_feature_post!(&self, generic_associated_types, ti.span,
"where clauses on associated types are unstable");
}
}
_ => {}
}
visit::walk_trait_item(self, ti)
}
fn visit_impl_item(&mut self, ii: &'a ast::ImplItem) {
if ii.defaultness == ast::Defaultness::Default {
gate_feature_post!(&self, specialization,
ii.span,
"specialization is unstable");
}
match ii.node {
ast::ImplItemKind::Method(..) => {}
ast::ImplItemKind::OpaqueTy(..) => {
gate_feature_post!(
&self,
type_alias_impl_trait,
ii.span,
"`impl Trait` in type aliases is unstable"
);
}
ast::ImplItemKind::TyAlias(_) => {
if !ii.generics.params.is_empty() {
gate_feature_post!(&self, generic_associated_types, ii.span,
"generic associated types are unstable");
}
if !ii.generics.where_clause.predicates.is_empty() {
gate_feature_post!(&self, generic_associated_types, ii.span,
"where clauses on associated types are unstable");
}
}
_ => {}
}
visit::walk_impl_item(self, ii)
}
fn visit_vis(&mut self, vis: &'a ast::Visibility) {
if let ast::VisibilityKind::Crate(ast::CrateSugar::JustCrate) = vis.node {
gate_feature_post!(&self, crate_visibility_modifier, vis.span,
"`crate` visibility modifier is experimental");
}
visit::walk_vis(self, vis)
}
}
pub fn get_features(span_handler: &Handler, krate_attrs: &[ast::Attribute],
crate_edition: Edition, allow_features: &Option<Vec<String>>) -> Features {
fn feature_removed(span_handler: &Handler, span: Span, reason: Option<&str>) {
let mut err = struct_span_err!(span_handler, span, E0557, "feature has been removed");
if let Some(reason) = reason {
err.span_note(span, reason);
} else {
err.span_label(span, "feature has been removed");
}
err.emit();
}
let mut features = Features::new();
let mut edition_enabled_features = FxHashMap::default();
for &edition in ALL_EDITIONS {
if edition <= crate_edition {
// The `crate_edition` implies its respective umbrella feature-gate
// (i.e., `#![feature(rust_20XX_preview)]` isn't needed on edition 20XX).
edition_enabled_features.insert(edition.feature_name(), edition);
}
}
for feature in active_features_up_to(crate_edition) {
feature.set(&mut features, DUMMY_SP);
edition_enabled_features.insert(feature.name, crate_edition);
}
// Process the edition umbrella feature-gates first, to ensure
// `edition_enabled_features` is completed before it's queried.
for attr in krate_attrs {
if !attr.check_name(sym::feature) {
continue
}
let list = match attr.meta_item_list() {
Some(list) => list,
None => continue,
};
for mi in list {
if !mi.is_word() {
continue;
}
let name = mi.name_or_empty();
let edition = ALL_EDITIONS.iter().find(|e| name == e.feature_name()).copied();
if let Some(edition) = edition {
if edition <= crate_edition {
continue;
}
for feature in active_features_up_to(edition) {
// FIXME(Manishearth) there is currently no way to set
// lib features by edition
feature.set(&mut features, DUMMY_SP);
edition_enabled_features.insert(feature.name, edition);
}
}
}
}
for attr in krate_attrs {
if !attr.check_name(sym::feature) {
continue
}
let list = match attr.meta_item_list() {
Some(list) => list,
None => continue,
};
let bad_input = |span| {
struct_span_err!(span_handler, span, E0556, "malformed `feature` attribute input")
};
for mi in list {
let name = match mi.ident() {
Some(ident) if mi.is_word() => ident.name,
Some(ident) => {
bad_input(mi.span()).span_suggestion(
mi.span(),
"expected just one word",
format!("{}", ident.name),
Applicability::MaybeIncorrect,
).emit();
continue
}
None => {
bad_input(mi.span()).span_label(mi.span(), "expected just one word").emit();
continue
}
};
if let Some(edition) = edition_enabled_features.get(&name) {
struct_span_warn!(
span_handler,
mi.span(),
E0705,
"the feature `{}` is included in the Rust {} edition",
name,
edition,
).emit();
continue;
}
if ALL_EDITIONS.iter().any(|e| name == e.feature_name()) {
// Handled in the separate loop above.
continue;
}
let removed = REMOVED_FEATURES.iter().find(|f| name == f.name);
let stable_removed = STABLE_REMOVED_FEATURES.iter().find(|f| name == f.name);
if let Some(Feature { state, .. }) = removed.or(stable_removed) {
if let FeatureState::Removed { reason }
| FeatureState::Stabilized { reason } = state
{
feature_removed(span_handler, mi.span(), *reason);
continue;
}
}
if let Some(Feature { since, .. }) = ACCEPTED_FEATURES.iter().find(|f| name == f.name) {
let since = Some(Symbol::intern(since));
features.declared_lang_features.push((name, mi.span(), since));
continue;
}
if let Some(allowed) = allow_features.as_ref() {
if allowed.iter().find(|f| *f == name.as_str()).is_none() {
span_err!(span_handler, mi.span(), E0725,
"the feature `{}` is not in the list of allowed features",
name);
continue;
}
}
if let Some(f) = ACTIVE_FEATURES.iter().find(|f| name == f.name) {
f.set(&mut features, mi.span());
features.declared_lang_features.push((name, mi.span(), None));
continue;
}
features.declared_lib_features.push((name, mi.span()));
}
}
features
}
fn active_features_up_to(edition: Edition) -> impl Iterator<Item=&'static Feature> {
ACTIVE_FEATURES.iter()
.filter(move |feature| {
if let Some(feature_edition) = feature.edition {
feature_edition <= edition
} else {
false
}
})
}
pub fn check_crate(krate: &ast::Crate,
parse_sess: &ParseSess,
features: &Features,
unstable: UnstableFeatures) {
maybe_stage_features(&parse_sess.span_diagnostic, krate, unstable);
let mut visitor = PostExpansionVisitor { parse_sess, features };
macro_rules! gate_all {
($gate:ident, $msg:literal) => { gate_all!($gate, $gate, $msg); };
($spans:ident, $gate:ident, $msg:literal) => {
for span in &*parse_sess.gated_spans.$spans.borrow() {
gate_feature!(&visitor, $gate, *span, $msg);
}
}
}
gate_all!(let_chains, "`let` expressions in this position are experimental");
gate_all!(async_closure, "async closures are unstable");
gate_all!(yields, generators, "yield syntax is experimental");
gate_all!(or_patterns, "or-patterns syntax is experimental");
visit::walk_crate(&mut visitor, krate);
}
#[derive(Clone, Copy, Hash)]
pub enum UnstableFeatures {
/// Hard errors for unstable features are active, as on beta/stable channels.
Disallow,
/// Allow features to be activated, as on nightly.
Allow,
/// Errors are bypassed for bootstrapping. This is required any time
/// during the build that feature-related lints are set to warn or above
/// because the build turns on warnings-as-errors and uses lots of unstable
/// features. As a result, this is always required for building Rust itself.
Cheat
}
impl UnstableFeatures {
pub fn from_environment() -> UnstableFeatures {
// `true` if this is a feature-staged build, i.e., on the beta or stable channel.
let disable_unstable_features = option_env!("CFG_DISABLE_UNSTABLE_FEATURES").is_some();
// `true` if we should enable unstable features for bootstrapping.
let bootstrap = env::var("RUSTC_BOOTSTRAP").is_ok();
match (disable_unstable_features, bootstrap) {
(_, true) => UnstableFeatures::Cheat,
(true, _) => UnstableFeatures::Disallow,
(false, _) => UnstableFeatures::Allow
}
}
pub fn is_nightly_build(&self) -> bool {
match *self {
UnstableFeatures::Allow | UnstableFeatures::Cheat => true,
_ => false,
}
}
}
fn maybe_stage_features(span_handler: &Handler, krate: &ast::Crate, unstable: UnstableFeatures) {
let allow_features = match unstable {
UnstableFeatures::Allow => true,
UnstableFeatures::Disallow => false,
UnstableFeatures::Cheat => true
};
if !allow_features {
for attr in &krate.attrs {
if attr.check_name(sym::feature) {
let release_channel = option_env!("CFG_RELEASE_CHANNEL").unwrap_or("(unknown)");
span_err!(span_handler, attr.span, E0554,
"`#![feature]` may not be used on the {} release channel",
release_channel);
}
}
}
}
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