976 lines
37 KiB
Rust
976 lines
37 KiB
Rust
//! # Feature gating
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//!
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//! This module implements the gating necessary for preventing certain compiler
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//! features from being used by default. This module will crawl a pre-expanded
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//! AST to ensure that there are no features which are used that are not
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//! enabled.
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//!
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//! Features are enabled in programs via the crate-level attributes of
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//! `#![feature(...)]` with a comma-separated list of features.
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//!
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//! For the purpose of future feature-tracking, once code for detection of feature
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//! gate usage is added, *do not remove it again* even once the feature
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//! becomes stable.
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mod accepted;
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use accepted::ACCEPTED_FEATURES;
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mod removed;
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use removed::{REMOVED_FEATURES, STABLE_REMOVED_FEATURES};
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mod active;
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use active::{ACTIVE_FEATURES};
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pub use active::{Features, INCOMPLETE_FEATURES};
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mod builtin_attrs;
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pub use builtin_attrs::{
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AttributeGate, AttributeType, GatedCfg,
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BuiltinAttribute, BUILTIN_ATTRIBUTES, BUILTIN_ATTRIBUTE_MAP,
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deprecated_attributes, is_builtin_attr, is_builtin_attr_name,
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};
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use crate::ast::{
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self, AssocTyConstraint, AssocTyConstraintKind, NodeId, GenericParam, GenericParamKind,
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PatKind, RangeEnd,
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};
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use crate::attr::{self, check_builtin_attribute};
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use crate::source_map::Spanned;
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use crate::edition::{ALL_EDITIONS, Edition};
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use crate::visit::{self, FnKind, Visitor};
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use crate::parse::{token, ParseSess};
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use crate::parse::parser::Parser;
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use crate::symbol::{Symbol, sym};
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use crate::tokenstream::TokenTree;
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use errors::{Applicability, DiagnosticBuilder, Handler};
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use rustc_data_structures::fx::FxHashMap;
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use rustc_target::spec::abi::Abi;
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use syntax_pos::{Span, DUMMY_SP, MultiSpan};
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use log::debug;
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use std::env;
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#[derive(Copy, Clone, Debug)]
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pub enum Stability {
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Unstable,
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// First argument is tracking issue link; second argument is an optional
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// help message, which defaults to "remove this attribute"
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Deprecated(&'static str, Option<&'static str>),
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}
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struct Context<'a> {
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features: &'a Features,
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parse_sess: &'a ParseSess,
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plugin_attributes: &'a [(Symbol, AttributeType)],
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}
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macro_rules! gate_feature_fn {
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($cx: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr, $level: expr) => {{
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let (cx, has_feature, span,
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name, explain, level) = ($cx, $has_feature, $span, $name, $explain, $level);
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let has_feature: bool = has_feature(&$cx.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($name) {
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leveled_feature_err(cx.parse_sess, name, span, GateIssue::Language, explain, level)
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.emit();
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}
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}}
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}
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macro_rules! gate_feature {
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($cx: expr, $feature: ident, $span: expr, $explain: expr) => {
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gate_feature_fn!($cx, |x:&Features| x.$feature, $span,
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sym::$feature, $explain, GateStrength::Hard)
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};
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($cx: expr, $feature: ident, $span: expr, $explain: expr, $level: expr) => {
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gate_feature_fn!($cx, |x:&Features| x.$feature, $span,
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sym::$feature, $explain, $level)
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};
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}
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impl<'a> Context<'a> {
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fn check_attribute(
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&self,
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attr: &ast::Attribute,
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attr_info: Option<&BuiltinAttribute>,
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is_macro: bool
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) {
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debug!("check_attribute(attr = {:?})", attr);
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if let Some(&(name, ty, _template, ref gateage)) = attr_info {
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if let AttributeGate::Gated(_, name, desc, ref has_feature) = *gateage {
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if !attr.span.allows_unstable(name) {
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gate_feature_fn!(
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self, has_feature, attr.span, name, desc, GateStrength::Hard
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);
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}
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} else if name == sym::doc {
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if let Some(content) = attr.meta_item_list() {
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if content.iter().any(|c| c.check_name(sym::include)) {
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gate_feature!(self, external_doc, attr.span,
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"`#[doc(include = \"...\")]` is experimental"
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);
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}
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}
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}
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debug!("check_attribute: {:?} is builtin, {:?}, {:?}", attr.path, ty, gateage);
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return;
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} else {
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for segment in &attr.path.segments {
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if segment.ident.as_str().starts_with("rustc") {
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let msg = "attributes starting with `rustc` are \
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reserved for use by the `rustc` compiler";
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gate_feature!(self, rustc_attrs, segment.ident.span, msg);
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}
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}
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}
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for &(n, ty) in self.plugin_attributes {
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if attr.path == n {
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// Plugins can't gate attributes, so we don't check for it
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// unlike the code above; we only use this loop to
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// short-circuit to avoid the checks below.
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debug!("check_attribute: {:?} is registered by a plugin, {:?}", attr.path, ty);
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return;
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}
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}
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if !is_macro && !attr::is_known(attr) {
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// Only run the custom attribute lint during regular feature gate
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// checking. Macro gating runs before the plugin attributes are
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// registered, so we skip this in that case.
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let msg = format!("the attribute `{}` is currently unknown to the compiler and \
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may have meaning added to it in the future", attr.path);
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gate_feature!(self, custom_attribute, attr.span, &msg);
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}
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}
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}
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pub fn check_attribute(attr: &ast::Attribute, parse_sess: &ParseSess, features: &Features) {
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let cx = Context { features, parse_sess, plugin_attributes: &[] };
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cx.check_attribute(
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attr,
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attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name).map(|a| *a)),
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true
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);
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}
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fn find_lang_feature_issue(feature: Symbol) -> Option<u32> {
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if let Some(info) = ACTIVE_FEATURES.iter().find(|t| t.0 == feature) {
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let issue = info.2;
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// FIXME (#28244): enforce that active features have issue numbers
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// assert!(issue.is_some())
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issue
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} else {
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// search in Accepted, Removed, or Stable Removed features
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let found = ACCEPTED_FEATURES.iter().chain(REMOVED_FEATURES).chain(STABLE_REMOVED_FEATURES)
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.find(|t| t.0 == feature);
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match found {
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Some(&(_, _, issue, _)) => issue,
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None => panic!("Feature `{}` is not declared anywhere", feature),
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}
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}
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}
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pub enum GateIssue {
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Language,
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Library(Option<u32>)
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}
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#[derive(Debug, Copy, Clone, PartialEq)]
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pub enum GateStrength {
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/// A hard error. (Most feature gates should use this.)
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Hard,
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/// Only a warning. (Use this only as backwards-compatibility demands.)
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Soft,
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}
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pub fn emit_feature_err(
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sess: &ParseSess,
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feature: Symbol,
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span: Span,
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issue: GateIssue,
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explain: &str,
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) {
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feature_err(sess, feature, span, issue, explain).emit();
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}
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pub fn feature_err<'a, S: Into<MultiSpan>>(
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sess: &'a ParseSess,
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feature: Symbol,
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span: S,
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issue: GateIssue,
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explain: &str,
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) -> DiagnosticBuilder<'a> {
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leveled_feature_err(sess, feature, span, issue, explain, GateStrength::Hard)
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}
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fn leveled_feature_err<'a, S: Into<MultiSpan>>(
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sess: &'a ParseSess,
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feature: Symbol,
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span: S,
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issue: GateIssue,
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explain: &str,
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level: GateStrength,
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) -> DiagnosticBuilder<'a> {
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let diag = &sess.span_diagnostic;
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let issue = match issue {
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GateIssue::Language => find_lang_feature_issue(feature),
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GateIssue::Library(lib) => lib,
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};
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let mut err = match level {
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GateStrength::Hard => {
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diag.struct_span_err_with_code(span, explain, stringify_error_code!(E0658))
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}
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GateStrength::Soft => diag.struct_span_warn(span, explain),
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};
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match issue {
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None | Some(0) => {} // We still accept `0` as a stand-in for backwards compatibility
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Some(n) => {
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err.note(&format!(
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"for more information, see https://github.com/rust-lang/rust/issues/{}",
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n,
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));
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}
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}
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// #23973: do not suggest `#![feature(...)]` if we are in beta/stable
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if sess.unstable_features.is_nightly_build() {
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err.help(&format!("add `#![feature({})]` to the crate attributes to enable", feature));
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}
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// If we're on stable and only emitting a "soft" warning, add a note to
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// clarify that the feature isn't "on" (rather than being on but
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// warning-worthy).
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if !sess.unstable_features.is_nightly_build() && level == GateStrength::Soft {
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err.help("a nightly build of the compiler is required to enable this feature");
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}
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err
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}
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const EXPLAIN_BOX_SYNTAX: &str =
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"box expression syntax is experimental; you can call `Box::new` instead";
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pub const EXPLAIN_STMT_ATTR_SYNTAX: &str =
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"attributes on expressions are experimental";
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pub const EXPLAIN_ALLOW_INTERNAL_UNSTABLE: &str =
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"allow_internal_unstable side-steps feature gating and stability checks";
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pub const EXPLAIN_ALLOW_INTERNAL_UNSAFE: &str =
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"allow_internal_unsafe side-steps the unsafe_code lint";
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pub const EXPLAIN_UNSIZED_TUPLE_COERCION: &str =
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"unsized tuple coercion is not stable enough for use and is subject to change";
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struct PostExpansionVisitor<'a> {
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context: &'a Context<'a>,
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builtin_attributes: &'static FxHashMap<Symbol, &'static BuiltinAttribute>,
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}
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macro_rules! gate_feature_post {
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($cx: expr, $feature: ident, $span: expr, $explain: expr) => {{
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let (cx, span) = ($cx, $span);
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if !span.allows_unstable(sym::$feature) {
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gate_feature!(cx.context, $feature, span, $explain)
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}
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}};
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($cx: expr, $feature: ident, $span: expr, $explain: expr, $level: expr) => {{
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let (cx, span) = ($cx, $span);
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if !span.allows_unstable(sym::$feature) {
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gate_feature!(cx.context, $feature, span, $explain, $level)
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}
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}}
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}
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impl<'a> PostExpansionVisitor<'a> {
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fn check_abi(&self, abi: Abi, span: Span) {
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match abi {
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Abi::RustIntrinsic => {
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gate_feature_post!(&self, intrinsics, span,
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"intrinsics are subject to change");
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},
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Abi::PlatformIntrinsic => {
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gate_feature_post!(&self, platform_intrinsics, span,
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"platform intrinsics are experimental and possibly buggy");
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},
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Abi::Vectorcall => {
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gate_feature_post!(&self, abi_vectorcall, span,
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"vectorcall is experimental and subject to change");
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},
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Abi::Thiscall => {
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gate_feature_post!(&self, abi_thiscall, span,
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"thiscall is experimental and subject to change");
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},
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Abi::RustCall => {
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gate_feature_post!(&self, unboxed_closures, span,
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"rust-call ABI is subject to change");
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},
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Abi::PtxKernel => {
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gate_feature_post!(&self, abi_ptx, span,
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"PTX ABIs are experimental and subject to change");
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},
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Abi::Unadjusted => {
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gate_feature_post!(&self, abi_unadjusted, span,
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"unadjusted ABI is an implementation detail and perma-unstable");
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},
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Abi::Msp430Interrupt => {
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gate_feature_post!(&self, abi_msp430_interrupt, span,
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"msp430-interrupt ABI is experimental and subject to change");
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},
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Abi::X86Interrupt => {
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gate_feature_post!(&self, abi_x86_interrupt, span,
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"x86-interrupt ABI is experimental and subject to change");
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},
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Abi::AmdGpuKernel => {
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gate_feature_post!(&self, abi_amdgpu_kernel, span,
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"amdgpu-kernel ABI is experimental and subject to change");
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},
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// Stable
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Abi::Cdecl |
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Abi::Stdcall |
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Abi::Fastcall |
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Abi::Aapcs |
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Abi::Win64 |
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Abi::SysV64 |
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Abi::Rust |
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Abi::C |
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Abi::System => {}
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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| {
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self.builtin_attributes.get(&ident.name).map(|a| *a)
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});
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// Check for gated attributes.
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self.context.check_attribute(attr, attr_info, false);
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if attr.check_name(sym::doc) {
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if let Some(content) = attr.meta_item_list() {
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if content.len() == 1 && content[0].check_name(sym::cfg) {
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gate_feature_post!(&self, doc_cfg, attr.span,
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"`#[doc(cfg(...))]` is experimental"
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);
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} else if content.iter().any(|c| c.check_name(sym::masked)) {
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gate_feature_post!(&self, doc_masked, attr.span,
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"`#[doc(masked)]` is experimental"
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);
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} else if content.iter().any(|c| c.check_name(sym::spotlight)) {
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gate_feature_post!(&self, doc_spotlight, attr.span,
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"`#[doc(spotlight)]` is experimental"
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);
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} else if content.iter().any(|c| c.check_name(sym::alias)) {
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gate_feature_post!(&self, doc_alias, attr.span,
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"`#[doc(alias = \"...\")]` is experimental"
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);
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} else if content.iter().any(|c| c.check_name(sym::keyword)) {
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gate_feature_post!(&self, doc_keyword, attr.span,
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"`#[doc(keyword = \"...\")]` is experimental"
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);
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}
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}
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}
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match attr_info {
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// `rustc_dummy` doesn't have any restrictions specific to built-in attributes.
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Some(&(name, _, template, _)) if name != sym::rustc_dummy =>
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check_builtin_attribute(self.context.parse_sess, attr, name, template),
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_ => if let Some(TokenTree::Token(token)) = attr.tokens.trees().next() {
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if token == token::Eq {
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// All key-value attributes are restricted to meta-item syntax.
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attr.parse_meta(self.context.parse_sess).map_err(|mut err| err.emit()).ok();
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}
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}
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}
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}
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fn visit_name(&mut self, sp: Span, name: ast::Name) {
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if !name.as_str().is_ascii() {
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gate_feature_post!(
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&self,
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non_ascii_idents,
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self.context.parse_sess.source_map().def_span(sp),
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"non-ascii idents are not fully supported"
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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.node {
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ast::ItemKind::ForeignMod(ref foreign_module) => {
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self.check_abi(foreign_module.abi, i.span);
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}
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ast::ItemKind::Fn(..) => {
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if attr::contains_name(&i.attrs[..], sym::plugin_registrar) {
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gate_feature_post!(&self, plugin_registrar, i.span,
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"compiler plugins are experimental and possibly buggy");
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}
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if attr::contains_name(&i.attrs[..], sym::start) {
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gate_feature_post!(&self, start, i.span,
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"a `#[start]` function is an experimental \
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feature whose signature may change \
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over time");
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}
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if attr::contains_name(&i.attrs[..], sym::main) {
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gate_feature_post!(&self, main, i.span,
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"declaration of a non-standard `#[main]` \
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function may change over time, for now \
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a top-level `fn main()` is required");
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}
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}
|
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ast::ItemKind::Struct(..) => {
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for attr in attr::filter_by_name(&i.attrs[..], sym::repr) {
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|
for item in attr.meta_item_list().unwrap_or_else(Vec::new) {
|
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if item.check_name(sym::simd) {
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gate_feature_post!(&self, repr_simd, attr.span,
|
|
"SIMD types are experimental and possibly buggy");
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}
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}
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}
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|
}
|
|
|
|
ast::ItemKind::Enum(ast::EnumDef{ref variants, ..}, ..) => {
|
|
for variant in variants {
|
|
match (&variant.data, &variant.disr_expr) {
|
|
(ast::VariantData::Unit(..), _) => {},
|
|
(_, Some(disr_expr)) =>
|
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gate_feature_post!(
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&self,
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arbitrary_enum_discriminant,
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disr_expr.value.span,
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|
"discriminants on non-unit variants are experimental"),
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_ => {},
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}
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}
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let has_feature = self.context.features.arbitrary_enum_discriminant;
|
|
if !has_feature && !i.span.allows_unstable(sym::arbitrary_enum_discriminant) {
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Parser::maybe_report_invalid_custom_discriminants(
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self.context.parse_sess,
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&variants,
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);
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}
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}
|
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|
|
ast::ItemKind::Impl(_, polarity, defaultness, _, _, _, _) => {
|
|
if polarity == ast::ImplPolarity::Negative {
|
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gate_feature_post!(&self, optin_builtin_traits,
|
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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");
|
|
}
|
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|
|
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.context.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 &(name, .., f_edition, set) in ACTIVE_FEATURES {
|
|
if let Some(f_edition) = f_edition {
|
|
if f_edition <= crate_edition {
|
|
set(&mut features, DUMMY_SP);
|
|
edition_enabled_features.insert(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();
|
|
|
|
if let Some(edition) = ALL_EDITIONS.iter().find(|e| name == e.feature_name()) {
|
|
if *edition <= crate_edition {
|
|
continue;
|
|
}
|
|
|
|
for &(name, .., f_edition, set) in ACTIVE_FEATURES {
|
|
if let Some(f_edition) = f_edition {
|
|
if f_edition <= *edition {
|
|
// FIXME(Manishearth) there is currently no way to set
|
|
// lib features by edition
|
|
set(&mut features, DUMMY_SP);
|
|
edition_enabled_features.insert(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.0);
|
|
let stable_removed = STABLE_REMOVED_FEATURES.iter().find(|f| name == f.0);
|
|
if let Some((.., reason)) = removed.or(stable_removed) {
|
|
feature_removed(span_handler, mi.span(), *reason);
|
|
continue;
|
|
}
|
|
|
|
if let Some((_, since, ..)) = ACCEPTED_FEATURES.iter().find(|f| name == f.0) {
|
|
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((.., set)) = ACTIVE_FEATURES.iter().find(|f| name == f.0) {
|
|
set(&mut features, mi.span());
|
|
features.declared_lang_features.push((name, mi.span(), None));
|
|
continue;
|
|
}
|
|
|
|
features.declared_lib_features.push((name, mi.span()));
|
|
}
|
|
}
|
|
|
|
features
|
|
}
|
|
|
|
pub fn check_crate(krate: &ast::Crate,
|
|
sess: &ParseSess,
|
|
features: &Features,
|
|
plugin_attributes: &[(Symbol, AttributeType)],
|
|
unstable: UnstableFeatures) {
|
|
maybe_stage_features(&sess.span_diagnostic, krate, unstable);
|
|
let ctx = Context {
|
|
features,
|
|
parse_sess: sess,
|
|
plugin_attributes,
|
|
};
|
|
|
|
macro_rules! gate_all {
|
|
($gate:ident, $msg:literal) => { gate_all!($gate, $gate, $msg); };
|
|
($spans:ident, $gate:ident, $msg:literal) => {
|
|
for span in &*sess.gated_spans.$spans.borrow() {
|
|
gate_feature!(&ctx, $gate, *span, $msg);
|
|
}
|
|
}
|
|
}
|
|
|
|
gate_all!(param_attrs, "attributes on function parameters are unstable");
|
|
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");
|
|
|
|
let visitor = &mut PostExpansionVisitor {
|
|
context: &ctx,
|
|
builtin_attributes: &*BUILTIN_ATTRIBUTE_MAP,
|
|
};
|
|
visit::walk_crate(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 {
|
|
// Whether 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();
|
|
// Whether 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);
|
|
}
|
|
}
|
|
}
|
|
}
|