move UnstableFeatures -> rustc_feature

Author: Centril

src/librustc/session/config.rs

@@ -7,6 +7,7 @@ use crate::session::{early_error, early_warn, Session};
 use crate::session::search_paths::SearchPath;
 
 use rustc_data_structures::fx::FxHashSet;
+use rustc_feature::UnstableFeatures;
 
 use rustc_target::spec::{LinkerFlavor, MergeFunctions, PanicStrategy, RelroLevel};
 use rustc_target::spec::{Target, TargetTriple};
@@ -16,7 +17,6 @@ use syntax::ast;
 use syntax::source_map::{FileName, FilePathMapping};
 use syntax::edition::{Edition, EDITION_NAME_LIST, DEFAULT_EDITION};
 use syntax::symbol::{sym, Symbol};
-use syntax::feature_gate::UnstableFeatures;
 
 use errors::emitter::HumanReadableErrorType;
 use errors::{ColorConfig, FatalError, Handler};
@@ -2701,7 +2701,7 @@ pub fn parse_crate_types_from_list(list_list: Vec<String>) -> Result<Vec<CrateTy
 
 pub mod nightly_options {
     use getopts;
-    use syntax::feature_gate::UnstableFeatures;
+    use rustc_feature::UnstableFeatures;
     use super::{ErrorOutputType, OptionStability, RustcOptGroup};
     use crate::session::early_error;
 
@@ -2850,9 +2850,9 @@ mod dep_tracking {
     use super::{CrateType, DebugInfo, ErrorOutputType, OptLevel, OutputTypes,
                 Passes, Sanitizer, LtoCli, LinkerPluginLto, SwitchWithOptPath,
                 SymbolManglingVersion};
+    use rustc_feature::UnstableFeatures;
     use rustc_target::spec::{MergeFunctions, PanicStrategy, RelroLevel, TargetTriple};
     use syntax::edition::Edition;
-    use syntax::feature_gate::UnstableFeatures;
 
     pub trait DepTrackingHash {
         fn hash(&self, hasher: &mut DefaultHasher, error_format: ErrorOutputType);

src/librustc_codegen_llvm/lib.rs

@@ -30,6 +30,7 @@ extern crate libc;
 #[macro_use] extern crate rustc;
 extern crate rustc_target;
 #[macro_use] extern crate rustc_data_structures;
+extern crate rustc_feature;
 extern crate rustc_index;
 extern crate rustc_incremental;
 extern crate rustc_codegen_utils;

src/librustc_codegen_llvm/llvm_util.rs

@@ -6,7 +6,7 @@ use rustc::session::config::PrintRequest;
 use rustc_target::spec::{MergeFunctions, PanicStrategy};
 use libc::c_int;
 use std::ffi::CString;
-use syntax::feature_gate::UnstableFeatures;
+use rustc_feature::UnstableFeatures;
 use syntax::symbol::sym;
 
 use std::str;

src/librustc_driver/lib.rs

@@ -44,8 +44,7 @@ use errors::{PResult, registry::Registry};
 use rustc_interface::interface;
 use rustc_interface::util::get_codegen_sysroot;
 use rustc_data_structures::sync::SeqCst;
-use rustc_feature::find_gated_cfg;
-
+use rustc_feature::{find_gated_cfg, UnstableFeatures};
 use rustc_serialize::json::ToJson;
 
 use std::borrow::Cow;
@@ -62,8 +61,7 @@ use std::str;
 use std::time::Instant;
 
 use syntax::ast;
-use syntax::source_map::FileLoader;
-use syntax::feature_gate::UnstableFeatures;
+use syntax_pos::source_map::FileLoader;
 use syntax_pos::symbol::sym;
 use syntax_pos::FileName;
 

src/librustc_feature/lib.rs

@@ -65,6 +65,40 @@ pub enum Stability {
     Deprecated(&'static str, Option<&'static str>),
 }
 
+#[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 = std::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,
+            UnstableFeatures::Disallow => false,
+        }
+    }
+}
+
 pub use accepted::ACCEPTED_FEATURES;
 pub use active::{ACTIVE_FEATURES, Features, INCOMPLETE_FEATURES};
 pub use removed::{REMOVED_FEATURES, STABLE_REMOVED_FEATURES};

src/librustdoc/core.rs

@@ -12,12 +12,12 @@ use rustc::session::DiagnosticOutput;
 use rustc::util::nodemap::{FxHashMap, FxHashSet};
 use rustc_interface::interface;
 use rustc_driver::abort_on_err;
+use rustc_feature::UnstableFeatures;
 use rustc_resolve as resolve;
 
 use syntax::ast::CRATE_NODE_ID;
 use syntax::source_map;
 use syntax::attr;
-use syntax::feature_gate::UnstableFeatures;
 use errors::json::JsonEmitter;
 use syntax::symbol::sym;
 use syntax_pos::DUMMY_SP;

src/librustdoc/externalfiles.rs

@@ -2,7 +2,7 @@ use std::fs;
 use std::path::Path;
 use std::str;
 use errors;
-use crate::syntax::feature_gate::UnstableFeatures;
+use rustc_feature::UnstableFeatures;
 use crate::syntax::edition::Edition;
 use crate::html::markdown::{IdMap, ErrorCodes, Markdown, Playground};
 

src/librustdoc/html/render.rs

@@ -45,7 +45,6 @@ use errors;
 use serialize::json::{ToJson, Json, as_json};
 use syntax::ast;
 use syntax::edition::Edition;
-use syntax::feature_gate::UnstableFeatures;
 use syntax::print::pprust;
 use syntax::source_map::FileName;
 use syntax::symbol::{Symbol, sym};
@@ -56,6 +55,7 @@ use rustc::middle::stability;
 use rustc::hir;
 use rustc::util::nodemap::{FxHashMap, FxHashSet};
 use rustc_data_structures::flock;
+use rustc_feature::UnstableFeatures;
 
 use crate::clean::{self, AttributesExt, Deprecation, GetDefId, SelfTy, Mutability};
 use crate::config::RenderOptions;

src/librustdoc/markdown.rs

@@ -6,7 +6,7 @@ use errors;
 use testing;
 use syntax::edition::Edition;
 use syntax::source_map::DUMMY_SP;
-use syntax::feature_gate::UnstableFeatures;
+use rustc_feature::UnstableFeatures;
 
 use crate::externalfiles::{LoadStringError, load_string};
 use crate::config::{Options, RenderOptions};

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -5,10 +5,10 @@ use rustc::hir;
 use rustc::lint as lint;
 use rustc::ty;
 use rustc_resolve::ParentScope;
+use rustc_feature::UnstableFeatures;
 use syntax;
 use syntax::ast::{self, Ident};
 use syntax_expand::base::SyntaxExtensionKind;
-use syntax::feature_gate::UnstableFeatures;
 use syntax::symbol::Symbol;
 use syntax_pos::DUMMY_SP;