move GateIssue to rustc_feature & simplify emit_feature_err

src/librustc/lint/levels.rs

@@ -232,13 +232,13 @@ impl<'a> LintLevelsBuilder<'a> {
                             // don't have any lint names (`#[level(reason = "foo")]`)
                             if let ast::LitKind::Str(rationale, _) = name_value.kind {
                                 if !self.sess.features_untracked().lint_reasons {
-                                    feature_gate::emit_feature_err(
+                                    feature_gate::feature_err(
                                         &self.sess.parse_sess,
                                         sym::lint_reasons,
                                         item.span,
-                                        feature_gate::GateIssue::Language,
                                         "lint reasons are experimental"
-                                    );
+                                    )
+                                    .emit();
                                 }
                                 reason = Some(rationale);
                             } else {

src/librustc/middle/stability.rs

@@ -13,11 +13,12 @@ use crate::ty::query::Providers;
 use crate::middle::privacy::AccessLevels;
 use crate::session::{DiagnosticMessageId, Session};
 use errors::DiagnosticBuilder;
+use rustc_feature::GateIssue;
 use syntax::symbol::{Symbol, sym};
 use syntax_pos::{Span, MultiSpan};
 use syntax::ast::{Attribute, CRATE_NODE_ID};
 use syntax::errors::Applicability;
-use syntax::feature_gate::{GateIssue, emit_feature_err};
+use syntax::feature_gate::{feature_err, feature_err_issue};
 use syntax::attr::{self, Stability, Deprecation, RustcDeprecation};
 use crate::ty::{self, TyCtxt};
 use crate::util::nodemap::{FxHashSet, FxHashMap};
@@ -512,9 +513,8 @@ pub fn report_unstable(
         if is_soft {
             soft_handler(lint::builtin::SOFT_UNSTABLE, span, &msg)
         } else {
-            emit_feature_err(
-                &sess.parse_sess, feature, span, GateIssue::Library(issue), &msg
-            );
+            feature_err_issue(&sess.parse_sess, feature, span, GateIssue::Library(issue), &msg)
+                .emit();
         }
     }
 }
@@ -842,15 +842,19 @@ impl Visitor<'tcx> for Checker<'tcx> {
                 let ty = self.tcx.type_of(def_id);
 
                 if adt_def.has_dtor(self.tcx) {
-                    emit_feature_err(&self.tcx.sess.parse_sess,
-                                     sym::untagged_unions, item.span, GateIssue::Language,
-                                     "unions with `Drop` implementations are unstable");
+                    feature_err(
+                        &self.tcx.sess.parse_sess, sym::untagged_unions, item.span,
+                        "unions with `Drop` implementations are unstable"
+                    )
+                    .emit();
                 } else {
                     let param_env = self.tcx.param_env(def_id);
                     if !param_env.can_type_implement_copy(self.tcx, ty).is_ok() {
-                        emit_feature_err(&self.tcx.sess.parse_sess,
-                                         sym::untagged_unions, item.span, GateIssue::Language,
-                                         "unions with non-`Copy` fields are unstable");
+                        feature_err(
+                            &self.tcx.sess.parse_sess, sym::untagged_unions, item.span,
+                            "unions with non-`Copy` fields are unstable"
+                        )
+                        .emit();
                     }
                 }
             }

src/librustc_feature/lib.rs

@@ -49,8 +49,7 @@ pub struct Feature {
 }
 
 impl Feature {
-    // FIXME(Centril): privatize again.
-    pub fn issue(&self) -> Option<NonZeroU32> {
+    fn issue(&self) -> Option<NonZeroU32> {
         self.issue.and_then(|i| NonZeroU32::new(i))
     }
 }
@@ -97,6 +96,37 @@ impl UnstableFeatures {
     }
 }
 
+fn find_lang_feature_issue(feature: Symbol) -> Option<NonZeroU32> {
+    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(found) => found.issue(),
+            None => panic!("feature `{}` is not declared anywhere", feature),
+        }
+    }
+}
+
+pub enum GateIssue {
+    Language,
+    Library(Option<NonZeroU32>)
+}
+
+pub fn find_feature_issue(feature: Symbol, issue: GateIssue) -> Option<NonZeroU32> {
+    match issue {
+        GateIssue::Language => find_lang_feature_issue(feature),
+        GateIssue::Library(lib) => lib,
+    }
+}
+
 pub use accepted::ACCEPTED_FEATURES;
 pub use active::{ACTIVE_FEATURES, Features, INCOMPLETE_FEATURES};
 pub use removed::{REMOVED_FEATURES, STABLE_REMOVED_FEATURES};

src/librustc_metadata/native_libs.rs

@@ -7,7 +7,7 @@ use rustc::util::nodemap::FxHashSet;
 use rustc_target::spec::abi::Abi;
 use syntax::attr;
 use syntax::source_map::Span;
-use syntax::feature_gate::{self, GateIssue};
+use syntax::feature_gate::feature_err;
 use syntax::symbol::{kw, sym, Symbol};
 use syntax::{span_err, struct_span_err};
 
@@ -158,27 +158,29 @@ impl Collector<'tcx> {
             }
         }
         if lib.cfg.is_some() && !self.tcx.features().link_cfg {
-            feature_gate::emit_feature_err(&self.tcx.sess.parse_sess,
-                                           sym::link_cfg,
-                                           span.unwrap(),
-                                           GateIssue::Language,
-                                           "is unstable");
+            feature_err(&self.tcx.sess.parse_sess, sym::link_cfg, span.unwrap(), "is unstable")
+                .emit();
         }
         if lib.kind == cstore::NativeStaticNobundle &&
-           !self.tcx.features().static_nobundle {
-            feature_gate::emit_feature_err(&self.tcx.sess.parse_sess,
-                                           sym::static_nobundle,
-                                           span.unwrap_or_else(|| syntax_pos::DUMMY_SP),
-                                           GateIssue::Language,
-                                           "kind=\"static-nobundle\" is unstable");
+           !self.tcx.features().static_nobundle
+        {
+            feature_err(
+                &self.tcx.sess.parse_sess,
+                sym::static_nobundle,
+                span.unwrap_or_else(|| syntax_pos::DUMMY_SP),
+                "kind=\"static-nobundle\" is unstable"
+            )
+            .emit();
         }
         if lib.kind == cstore::NativeRawDylib &&
            !self.tcx.features().raw_dylib {
-            feature_gate::emit_feature_err(&self.tcx.sess.parse_sess,
-                                           sym::raw_dylib,
-                                           span.unwrap_or_else(|| syntax_pos::DUMMY_SP),
-                                           GateIssue::Language,
-                                           "kind=\"raw-dylib\" is unstable");
+            feature_err(
+                &self.tcx.sess.parse_sess,
+                sym::raw_dylib,
+                span.unwrap_or_else(|| syntax_pos::DUMMY_SP),
+                "kind=\"raw-dylib\" is unstable"
+            )
+            .emit();
         }
         self.libs.push(lib);
     }

src/librustc_mir/transform/check_consts/ops.rs

@@ -4,7 +4,7 @@ use rustc::hir::def_id::DefId;
 use rustc::mir::BorrowKind;
 use rustc::session::config::nightly_options;
 use rustc::ty::TyCtxt;
-use syntax::feature_gate::{emit_feature_err, GateIssue};
+use syntax::feature_gate::feature_err;
 use syntax::symbol::sym;
 use syntax_pos::{Span, Symbol};
 
@@ -222,13 +222,13 @@ impl NonConstOp for Panic {
     }
 
     fn emit_error(&self, item: &Item<'_, '_>, span: Span) {
-        emit_feature_err(
+        feature_err(
             &item.tcx.sess.parse_sess,
             sym::const_panic,
             span,
-            GateIssue::Language,
             &format!("panicking in {}s is unstable", item.const_kind()),
-        );
+        )
+        .emit();
     }
 }
 
@@ -240,13 +240,13 @@ impl NonConstOp for RawPtrComparison {
     }
 
     fn emit_error(&self, item: &Item<'_, '_>, span: Span) {
-        emit_feature_err(
+        feature_err(
             &item.tcx.sess.parse_sess,
             sym::const_compare_raw_pointers,
             span,
-            GateIssue::Language,
             &format!("comparing raw pointers inside {}", item.const_kind()),
-        );
+        )
+        .emit();
     }
 }
 
@@ -258,14 +258,14 @@ impl NonConstOp for RawPtrDeref {
     }
 
     fn emit_error(&self, item: &Item<'_, '_>, span: Span) {
-        emit_feature_err(
-            &item.tcx.sess.parse_sess, sym::const_raw_ptr_deref,
-            span, GateIssue::Language,
+        feature_err(
+            &item.tcx.sess.parse_sess, sym::const_raw_ptr_deref, span,
             &format!(
                 "dereferencing raw pointers in {}s is unstable",
                 item.const_kind(),
             ),
-        );
+        )
+        .emit();
     }
 }
 
@@ -277,14 +277,14 @@ impl NonConstOp for RawPtrToIntCast {
     }
 
     fn emit_error(&self, item: &Item<'_, '_>, span: Span) {
-        emit_feature_err(
-            &item.tcx.sess.parse_sess, sym::const_raw_ptr_to_usize_cast,
-            span, GateIssue::Language,
+        feature_err(
+            &item.tcx.sess.parse_sess, sym::const_raw_ptr_to_usize_cast, span,
             &format!(
                 "casting pointers to integers in {}s is unstable",
                 item.const_kind(),
             ),
-        );
+        )
+        .emit();
     }
 }
 
@@ -334,11 +334,11 @@ impl NonConstOp for Transmute {
     }
 
     fn emit_error(&self, item: &Item<'_, '_>, span: Span) {
-        emit_feature_err(
-            &item.tcx.sess.parse_sess, sym::const_transmute,
-            span, GateIssue::Language,
-            &format!("The use of std::mem::transmute() \
-            is gated in {}s", item.const_kind()));
+        feature_err(
+            &item.tcx.sess.parse_sess, sym::const_transmute, span,
+            &format!("The use of std::mem::transmute() is gated in {}s", item.const_kind())
+        )
+        .emit();
     }
 }
 
@@ -355,10 +355,10 @@ impl NonConstOp for UnionAccess {
     }
 
     fn emit_error(&self, item: &Item<'_, '_>, span: Span) {
-        emit_feature_err(
-            &item.tcx.sess.parse_sess, sym::const_fn_union,
-            span, GateIssue::Language,
+        feature_err(
+            &item.tcx.sess.parse_sess, sym::const_fn_union, span,
             "unions in const fn are unstable",
-        );
+        )
+        .emit();
     }
 }

src/librustc_parse/config.rs

@@ -11,7 +11,7 @@
 use crate::validate_attr;
 use rustc_feature::Features;
 use syntax::attr::HasAttrs;
-use syntax::feature_gate::{feature_err, get_features, GateIssue};
+use syntax::feature_gate::{feature_err, get_features};
 use syntax::attr;
 use syntax::ast;
 use syntax::edition::Edition;
@@ -212,7 +212,6 @@ impl<'a> StripUnconfigured<'a> {
             let mut err = feature_err(self.sess,
                                       sym::stmt_expr_attributes,
                                       attr.span,
-                                      GateIssue::Language,
                                       "attributes on expressions are experimental");
 
             if attr.is_doc_comment() {

src/librustc_passes/check_const.rs

@@ -15,7 +15,7 @@ use rustc::ty::TyCtxt;
 use rustc::ty::query::Providers;
 use rustc_feature::Features;
 use syntax::ast::Mutability;
-use syntax::feature_gate::{emit_feature_err, GateIssue};
+use syntax::feature_gate::feature_err;
 use syntax::span_err;
 use syntax_pos::{sym, Span};
 use rustc_error_codes::*;
@@ -141,13 +141,7 @@ impl<'tcx> CheckConstVisitor<'tcx> {
             | NonConstExpr::Match(hir::MatchSource::Normal)
             | NonConstExpr::Match(hir::MatchSource::IfDesugar { .. })
             | NonConstExpr::Match(hir::MatchSource::IfLetDesugar { .. })
-            => emit_feature_err(
-                &self.tcx.sess.parse_sess,
-                sym::const_if_match,
-                span,
-                GateIssue::Language,
-                &msg
-            ),
+            => feature_err(&self.tcx.sess.parse_sess, sym::const_if_match, span, &msg).emit(),
 
             _ => span_err!(self.tcx.sess, span, E0744, "{}", msg),
         }

src/librustc_resolve/macros.rs

@@ -16,7 +16,7 @@ use rustc_feature::is_builtin_attr_name;
 use syntax::ast::{self, NodeId, Ident};
 use syntax::attr::{self, StabilityLevel};
 use syntax::edition::Edition;
-use syntax::feature_gate::{emit_feature_err, GateIssue};
+use syntax::feature_gate::feature_err;
 use syntax::print::pprust;
 use syntax_expand::base::{self, InvocationRes, Indeterminate};
 use syntax_expand::base::SyntaxExtension;
@@ -346,13 +346,8 @@ impl<'a> Resolver<'a> {
                segment.ident.as_str().starts_with("rustc") {
                 let msg =
                     "attributes starting with `rustc` are reserved for use by the `rustc` compiler";
-                emit_feature_err(
-                    &self.session.parse_sess,
-                    sym::rustc_attrs,
-                    segment.ident.span,
-                    GateIssue::Language,
-                    msg,
-                );
+                feature_err(&self.session.parse_sess, sym::rustc_attrs, segment.ident.span, msg)
+                    .emit();
             }
         }
 

src/librustc_typeck/astconv.rs

@@ -23,7 +23,7 @@ use crate::require_c_abi_if_c_variadic;
 use smallvec::SmallVec;
 use syntax::ast;
 use syntax::errors::pluralize;
-use syntax::feature_gate::{GateIssue, emit_feature_err};
+use syntax::feature_gate::feature_err;
 use syntax::util::lev_distance::find_best_match_for_name;
 use syntax::symbol::sym;
 use syntax_pos::{DUMMY_SP, Span, MultiSpan};
@@ -914,8 +914,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             } else {
                 "parenthetical notation is only stable when used with `Fn`-family traits"
             };
-            emit_feature_err(&self.tcx().sess.parse_sess, sym::unboxed_closures,
-                             span, GateIssue::Language, msg);
+            feature_err(&self.tcx().sess.parse_sess, sym::unboxed_closures, span, msg).emit();
         }
 
         self.create_substs_for_ast_path(span,

src/librustc_typeck/check/coercion.rs

@@ -644,13 +644,13 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         }
 
         if has_unsized_tuple_coercion && !self.tcx.features().unsized_tuple_coercion {
-            feature_gate::emit_feature_err(
+            feature_gate::feature_err(
                 &self.tcx.sess.parse_sess,
                 sym::unsized_tuple_coercion,
                 self.cause.span,
-                feature_gate::GateIssue::Language,
                 "unsized tuple coercion is not stable enough for use and is subject to change",
-            );
+            )
+            .emit();
         }
 
         Ok(coercion)