emit feature help in cheat mode (fix nightlies)

src/librustc/middle/stability.rs

@@ -411,8 +411,8 @@ impl<'a, 'tcx> Checker<'a, 'tcx> {
                                                &feature, &r),
                         None => format!("use of unstable library feature '{}'", &feature)
                     };
-                    emit_feature_err(&self.tcx.sess.parse_sess.span_diagnostic,
-                                      &feature, span, GateIssue::Library(Some(issue)), &msg);
+                    emit_feature_err(&self.tcx.sess.parse_sess, &feature, span,
+                                     GateIssue::Library(Some(issue)), &msg);
                 }
             }
             Some(&Stability { ref level, ref feature, .. }) => {

src/librustc/session/config.rs

@@ -37,7 +37,6 @@ use std::collections::btree_map::Iter as BTreeMapIter;
 use std::collections::btree_map::Keys as BTreeMapKeysIter;
 use std::collections::btree_map::Values as BTreeMapValuesIter;
 
-use std::env;
 use std::fmt;
 use std::hash::{Hasher, SipHasher};
 use std::iter::FromIterator;
@@ -1525,27 +1524,12 @@ pub fn build_session_options_and_crate_config(matches: &getopts::Matches)
         crate_name: crate_name,
         alt_std_name: None,
         libs: libs,
-        unstable_features: get_unstable_features_setting(),
+        unstable_features: UnstableFeatures::from_environment(),
         debug_assertions: debug_assertions,
     },
     cfg)
 }
 
-pub fn get_unstable_features_setting() -> 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();
-    // The secret key needed to get through the rustc build itself by
-    // subverting the unstable features lints
-    let bootstrap_secret_key = option_env!("CFG_BOOTSTRAP_KEY");
-    // The matching key to the above, only known by the build system
-    let bootstrap_provided_key = env::var("RUSTC_BOOTSTRAP_KEY").ok();
-    match (disable_unstable_features, bootstrap_secret_key, bootstrap_provided_key) {
-        (_, Some(ref s), Some(ref p)) if s == p => UnstableFeatures::Cheat,
-        (true, ..) => UnstableFeatures::Disallow,
-        (false, ..) => UnstableFeatures::Allow
-    }
-}
-
 pub fn parse_crate_types_from_list(list_list: Vec<String>) -> Result<Vec<CrateType>, String> {
     let mut crate_types: Vec<CrateType> = Vec::new();
     for unparsed_crate_type in &list_list {
@@ -1575,26 +1559,21 @@ 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 super::{ErrorOutputType, OptionStability, RustcOptGroup, get_unstable_features_setting};
+    use super::{ErrorOutputType, OptionStability, RustcOptGroup};
     use session::{early_error, early_warn};
 
     pub fn is_unstable_enabled(matches: &getopts::Matches) -> bool {
         is_nightly_build() && matches.opt_strs("Z").iter().any(|x| *x == "unstable-options")
     }
 
     pub fn is_nightly_build() -> bool {
-        match get_unstable_features_setting() {
-            UnstableFeatures::Allow | UnstableFeatures::Cheat => true,
-            _ => false,
-        }
+        UnstableFeatures::from_environment().is_nightly_build()
     }
 
     pub fn check_nightly_options(matches: &getopts::Matches, flags: &[RustcOptGroup]) {
         let has_z_unstable_option = matches.opt_strs("Z").iter().any(|x| *x == "unstable-options");
-        let really_allows_unstable_options = match get_unstable_features_setting() {
-            UnstableFeatures::Disallow => false,
-            _ => true,
-        };
+        let really_allows_unstable_options = UnstableFeatures::from_environment()
+            .is_nightly_build();
 
         for opt in flags.iter() {
             if opt.stability == OptionStability::Stable {

src/librustc_driver/lib.rs

@@ -73,7 +73,7 @@ use rustc_trans::back::write::{create_target_machine, RELOC_MODEL_ARGS, CODE_GEN
 use rustc::dep_graph::DepGraph;
 use rustc::session::{self, config, Session, build_session, CompileResult};
 use rustc::session::config::{Input, PrintRequest, OutputType, ErrorOutputType};
-use rustc::session::config::{get_unstable_features_setting, nightly_options};
+use rustc::session::config::nightly_options;
 use rustc::lint::Lint;
 use rustc::lint;
 use rustc_metadata::loader;
@@ -649,10 +649,8 @@ impl RustcDefaultCalls {
                     }
                 }
                 PrintRequest::Cfg => {
-                    let allow_unstable_cfg = match get_unstable_features_setting() {
-                        UnstableFeatures::Disallow => false,
-                        _ => true,
-                    };
+                    let allow_unstable_cfg = UnstableFeatures::from_environment()
+                        .is_nightly_build();
 
                     for cfg in cfg {
                         if !allow_unstable_cfg && GatedCfg::gate(&*cfg).is_some() {

src/librustc_passes/static_recursion.rs

@@ -143,7 +143,7 @@ impl<'a, 'ast: 'a> CheckItemRecursionVisitor<'a, 'ast> {
             });
             if any_static {
                 if !self.sess.features.borrow().static_recursion {
-                    emit_feature_err(&self.sess.parse_sess.span_diagnostic,
+                    emit_feature_err(&self.sess.parse_sess,
                                      "static_recursion",
                                      *self.root_span,
                                      GateIssue::Language,

src/librustc_resolve/macros.rs

@@ -146,9 +146,9 @@ impl<'a> Resolver<'a> {
 
     fn insert_custom_derive(&mut self, name: &str, ext: Rc<MultiItemModifier>, sp: Span) {
         if !self.session.features.borrow().rustc_macro {
-            let diagnostic = &self.session.parse_sess.span_diagnostic;
+            let sess = &self.session.parse_sess;
             let msg = "loading custom derive macro crates is experimentally supported";
-            emit_feature_err(diagnostic, "rustc_macro", sp, feature_gate::GateIssue::Language, msg);
+            emit_feature_err(sess, "rustc_macro", sp, feature_gate::GateIssue::Language, msg);
         }
         if self.derive_modes.insert(token::intern(name), ext).is_some() {
             self.session.span_err(sp, &format!("cannot shadow existing derive mode `{}`", name));

src/librustc_typeck/astconv.rs

@@ -795,7 +795,7 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
                 // For now, require that parenthetical notation be used
                 // only with `Fn()` etc.
                 if !self.tcx().sess.features.borrow().unboxed_closures && trait_def.paren_sugar {
-                    emit_feature_err(&self.tcx().sess.parse_sess.span_diagnostic,
+                    emit_feature_err(&self.tcx().sess.parse_sess,
                                      "unboxed_closures", span, GateIssue::Language,
                                      "\
                         the precise format of `Fn`-family traits' \
@@ -807,7 +807,7 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
                 // For now, require that parenthetical notation be used
                 // only with `Fn()` etc.
                 if !self.tcx().sess.features.borrow().unboxed_closures && !trait_def.paren_sugar {
-                    emit_feature_err(&self.tcx().sess.parse_sess.span_diagnostic,
+                    emit_feature_err(&self.tcx().sess.parse_sess,
                                      "unboxed_closures", span, GateIssue::Language,
                                      "\
                         parenthetical notation is only stable when used with `Fn`-family traits");

src/librustc_typeck/check/mod.rs

@@ -3256,7 +3256,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         if let Some((def_id, variant)) = variant {
             if variant.kind == ty::VariantKind::Tuple &&
                     !self.tcx.sess.features.borrow().relaxed_adts {
-                emit_feature_err(&self.tcx.sess.parse_sess.span_diagnostic,
+                emit_feature_err(&self.tcx.sess.parse_sess,
                                  "relaxed_adts", span, GateIssue::Language,
                                  "tuple structs and variants in struct patterns are unstable");
             }

src/librustdoc/html/markdown.rs

@@ -27,7 +27,6 @@
 #![allow(non_camel_case_types)]
 
 use libc;
-use rustc::session::config::get_unstable_features_setting;
 use std::ascii::AsciiExt;
 use std::cell::RefCell;
 use std::default::Default;
@@ -478,13 +477,10 @@ impl LangString {
         let mut data = LangString::all_false();
         let mut allow_compile_fail = false;
         let mut allow_error_code_check = false;
-        match get_unstable_features_setting() {
-            UnstableFeatures::Allow | UnstableFeatures::Cheat => {
-                allow_compile_fail = true;
-                allow_error_code_check = true;
-            }
-            _ => {},
-        };
+        if UnstableFeatures::from_environment().is_nightly_build() {
+            allow_compile_fail = true;
+            allow_error_code_check = true;
+        }
 
         let tokens = string.split(|c: char|
             !(c == '_' || c == '-' || c.is_alphanumeric())

src/librustdoc/html/render.rs

@@ -58,7 +58,6 @@ use syntax::feature_gate::UnstableFeatures;
 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefId, LOCAL_CRATE};
 use rustc::middle::privacy::AccessLevels;
 use rustc::middle::stability;
-use rustc::session::config::get_unstable_features_setting;
 use rustc::hir;
 use rustc::util::nodemap::{FnvHashMap, FnvHashSet};
 use rustc_data_structures::flock;
@@ -1971,7 +1970,7 @@ fn item_static(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
 fn item_function(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
                  f: &clean::Function) -> fmt::Result {
     // FIXME(#24111): remove when `const_fn` is stabilized
-    let vis_constness = match get_unstable_features_setting() {
+    let vis_constness = match UnstableFeatures::from_environment() {
         UnstableFeatures::Allow => f.constness,
         _ => hir::Constness::NotConst
     };
@@ -2250,7 +2249,7 @@ fn render_assoc_item(w: &mut fmt::Formatter,
             }
         };
         // FIXME(#24111): remove when `const_fn` is stabilized
-        let vis_constness = match get_unstable_features_setting() {
+        let vis_constness = match UnstableFeatures::from_environment() {
             UnstableFeatures::Allow => constness,
             _ => hir::Constness::NotConst
         };

src/librustdoc/test.rs

@@ -25,8 +25,7 @@ use rustc_lint;
 use rustc::dep_graph::DepGraph;
 use rustc::hir::map as hir_map;
 use rustc::session::{self, config};
-use rustc::session::config::{get_unstable_features_setting, OutputType,
-                             OutputTypes, Externs};
+use rustc::session::config::{OutputType, OutputTypes, Externs};
 use rustc::session::search_paths::{SearchPaths, PathKind};
 use rustc_back::dynamic_lib::DynamicLibrary;
 use rustc_back::tempdir::TempDir;
@@ -35,6 +34,7 @@ use rustc_driver::driver::phase_2_configure_and_expand;
 use rustc_metadata::cstore::CStore;
 use rustc_resolve::MakeGlobMap;
 use syntax::codemap::CodeMap;
+use syntax::feature_gate::UnstableFeatures;
 use errors;
 use errors::emitter::ColorConfig;
 
@@ -68,7 +68,7 @@ pub fn run(input: &str,
         search_paths: libs.clone(),
         crate_types: vec!(config::CrateTypeDylib),
         externs: externs.clone(),
-        unstable_features: get_unstable_features_setting(),
+        unstable_features: UnstableFeatures::from_environment(),
         ..config::basic_options().clone()
     };
 
@@ -197,7 +197,7 @@ fn runtest(test: &str, cratename: &str, cfgs: Vec<String>, libs: SearchPaths,
             .. config::basic_codegen_options()
         },
         test: as_test_harness,
-        unstable_features: get_unstable_features_setting(),
+        unstable_features: UnstableFeatures::from_environment(),
         ..config::basic_options().clone()
     };
 

src/libsyntax/config.rs

@@ -157,7 +157,7 @@ impl<'a> StripUnconfigured<'a> {
         // flag the offending attributes
         for attr in attrs.iter() {
             if !self.features.map(|features| features.stmt_expr_attributes).unwrap_or(true) {
-                emit_feature_err(&self.sess.span_diagnostic,
+                emit_feature_err(&self.sess,
                                  "stmt_expr_attributes",
                                  attr.span,
                                  GateIssue::Language,

src/libsyntax/ext/expand.rs

@@ -344,7 +344,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         // Detect use of feature-gated or invalid attributes on macro invoations
         // since they will not be detected after macro expansion.
         for attr in attrs.iter() {
-            feature_gate::check_attribute(&attr, &self.cx.parse_sess.span_diagnostic,
+            feature_gate::check_attribute(&attr, &self.cx.parse_sess,
                                           &self.cx.parse_sess.codemap(),
                                           &self.cx.ecfg.features.unwrap());
         }

src/libsyntax/feature_gate.rs

@@ -36,6 +36,7 @@ use parse::ParseSess;
 use parse::token::InternedString;
 
 use std::ascii::AsciiExt;
+use std::env;
 
 macro_rules! setter {
     ($field: ident) => {{
@@ -679,16 +680,15 @@ impl GatedCfg {
     pub fn check_and_emit(&self, sess: &ParseSess, features: &Features) {
         let (cfg, feature, has_feature) = GATED_CFGS[self.index];
         if !has_feature(features) && !sess.codemap().span_allows_unstable(self.span) {
-            let diagnostic = &sess.span_diagnostic;
             let explain = format!("`cfg({})` is experimental and subject to change", cfg);
-            emit_feature_err(diagnostic, feature, self.span, GateIssue::Language, &explain);
+            emit_feature_err(sess, feature, self.span, GateIssue::Language, &explain);
         }
     }
 }
 
 struct Context<'a> {
     features: &'a Features,
-    span_handler: &'a Handler,
+    parse_sess: &'a ParseSess,
     cm: &'a CodeMap,
     plugin_attributes: &'a [(String, AttributeType)],
 }
@@ -699,7 +699,7 @@ macro_rules! gate_feature_fn {
         let has_feature: bool = has_feature(&$cx.features);
         debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature);
         if !has_feature && !cx.cm.span_allows_unstable(span) {
-            emit_feature_err(cx.span_handler, name, span, GateIssue::Language, explain);
+            emit_feature_err(cx.parse_sess, name, span, GateIssue::Language, explain);
         }
     }}
 }
@@ -756,10 +756,10 @@ impl<'a> Context<'a> {
     }
 }
 
-pub fn check_attribute(attr: &ast::Attribute, handler: &Handler,
+pub fn check_attribute(attr: &ast::Attribute, parse_sess: &ParseSess,
                        cm: &CodeMap, features: &Features) {
     let cx = Context {
-        features: features, span_handler: handler,
+        features: features, parse_sess: parse_sess,
         cm: cm, plugin_attributes: &[]
     };
     cx.check_attribute(attr, true);
@@ -788,8 +788,10 @@ pub enum GateIssue {
     Library(Option<u32>)
 }
 
-pub fn emit_feature_err(diag: &Handler, feature: &str, span: Span, issue: GateIssue,
+pub fn emit_feature_err(sess: &ParseSess, feature: &str, span: Span, issue: GateIssue,
                         explain: &str) {
+    let diag = &sess.span_diagnostic;
+
     let issue = match issue {
         GateIssue::Language => find_lang_feature_issue(feature),
         GateIssue::Library(lib) => lib,
@@ -802,13 +804,12 @@ pub fn emit_feature_err(diag: &Handler, feature: &str, span: Span, issue: GateIs
     };
 
     // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
-    if option_env!("CFG_DISABLE_UNSTABLE_FEATURES").is_some() {
-        err.emit();
-        return;
+    if sess.unstable_features.is_nightly_build() {
+        err.help(&format!("add #![feature({})] to the \
+                           crate attributes to enable",
+                          feature));
     }
-    err.help(&format!("add #![feature({})] to the \
-                       crate attributes to enable",
-                      feature));
+
     err.emit();
 }
 
@@ -962,9 +963,10 @@ impl<'a> Visitor for PostExpansionVisitor<'a> {
                 if attr::contains_name(&i.attrs[..], "simd") {
                     gate_feature_post!(&self, simd, i.span,
                                        "SIMD types are experimental and possibly buggy");
-                    self.context.span_handler.span_warn(i.span,
-                                                        "the `#[simd]` attribute is deprecated, \
-                                                         use `#[repr(simd)]` instead");
+                    self.context.parse_sess.span_diagnostic.span_warn(i.span,
+                                                                      "the `#[simd]` attribute \
+                                                                       is deprecated, use \
+                                                                       `#[repr(simd)]` instead");
                 }
                 for attr in &i.attrs {
                     if attr.name() == "repr" {
@@ -1273,7 +1275,7 @@ pub fn check_crate(krate: &ast::Crate,
     maybe_stage_features(&sess.span_diagnostic, krate, unstable);
     let ctx = Context {
         features: features,
-        span_handler: &sess.span_diagnostic,
+        parse_sess: sess,
         cm: sess.codemap(),
         plugin_attributes: plugin_attributes,
     };
@@ -1294,6 +1296,30 @@ pub enum UnstableFeatures {
     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();
+        // The secret key needed to get through the rustc build itself by
+        // subverting the unstable features lints
+        let bootstrap_secret_key = option_env!("CFG_BOOTSTRAP_KEY");
+        // The matching key to the above, only known by the build system
+        let bootstrap_provided_key = env::var("RUSTC_BOOTSTRAP_KEY").ok();
+        match (disable_unstable_features, bootstrap_secret_key, bootstrap_provided_key) {
+            (_, Some(ref s), Some(ref p)) if s == p => 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 {