Allow tracking issues for lang features.

This is similar to the libs version, which allow an `issue` field in the
`#[unstable]` attribute.

cc #28244

Author: huonw

src/etc/featureck.py

@@ -47,20 +47,24 @@
                 is_feature_line = True
 
         if is_feature_line:
-            line = line.replace("(", "").replace("),", "").replace(")", "")
+            # turn `    ("foo", "1.0.0", Some(10), Active)` into
+            # `"foo", "1.0.0", Some(10), Active`
+            line = line.strip(' ,()')
             parts = line.split(",")
-            if len(parts) != 3:
+            if len(parts) != 4:
                 print("error: unexpected number of components in line: " + original_line)
                 sys.exit(1)
             feature_name = parts[0].strip().replace('"', "")
             since = parts[1].strip().replace('"', "")
-            status = parts[2].strip()
+            issue = parts[2].strip()
+            status = parts[3].strip()
             assert len(feature_name) > 0
             assert len(since) > 0
+            assert len(issue) > 0
             assert len(status) > 0
 
             language_feature_names += [feature_name]
-            language_features += [(feature_name, since, status)]
+            language_features += [(feature_name, since, issue, status)]
 
 assert len(language_features) > 0
 
@@ -158,7 +162,7 @@
     status = "unstable"
     stable_since = None
 
-    if f[2] == "Accepted":
+    if f[3] == "Accepted":
         status = "stable"
     if status == "stable":
         stable_since = f[1]

src/librustc/middle/check_static_recursion.rs

@@ -18,7 +18,7 @@ use util::nodemap::NodeMap;
 
 use syntax::{ast};
 use syntax::codemap::Span;
-use syntax::feature_gate::emit_feature_err;
+use syntax::feature_gate::{GateIssue, emit_feature_err};
 use rustc_front::visit::Visitor;
 use rustc_front::visit;
 use rustc_front::hir;
@@ -143,7 +143,7 @@ impl<'a, 'ast: 'a> CheckItemRecursionVisitor<'a, 'ast> {
                 if !self.sess.features.borrow().static_recursion {
                     emit_feature_err(&self.sess.parse_sess.span_diagnostic,
                                      "static_recursion",
-                                     *self.root_span, "recursive static");
+                                     *self.root_span, GateIssue::Language, "recursive static");
                 }
             } else {
                 span_err!(self.sess, *self.root_span, E0265, "recursive constant");

src/librustc/middle/stability.rs

@@ -22,7 +22,7 @@ use syntax::parse::token::InternedString;
 use syntax::codemap::{Span, DUMMY_SP};
 use syntax::ast;
 use syntax::ast::NodeId;
-use syntax::feature_gate::emit_feature_err;
+use syntax::feature_gate::{GateIssue, emit_feature_err};
 use util::nodemap::{DefIdMap, FnvHashSet, FnvHashMap};
 
 use rustc_front::hir;
@@ -294,18 +294,14 @@ impl<'a, 'tcx> Checker<'a, 'tcx> {
                 self.used_features.insert(feature.clone(), attr::Unstable);
 
                 if !self.active_features.contains(feature) {
-                    let mut msg = match *reason {
+                    let msg = match *reason {
                         Some(ref r) => format!("use of unstable library feature '{}': {}",
                                                &feature, &r),
                         None => format!("use of unstable library feature '{}'", &feature)
                     };
-                    if let Some(n) = issue {
-                        use std::fmt::Write;
-                        write!(&mut msg, " (see issue #{})", n).unwrap();
-                    }
 
                     emit_feature_err(&self.tcx.sess.parse_sess.span_diagnostic,
-                                      &feature, span, &msg);
+                                      &feature, span, GateIssue::Library(issue), &msg);
                 }
             }
             Some(&Stability { level, ref feature, .. }) => {

src/librustc_typeck/astconv.rs

@@ -70,7 +70,7 @@ use util::nodemap::FnvHashSet;
 use std::slice;
 use syntax::{abi, ast};
 use syntax::codemap::{Span, Pos};
-use syntax::feature_gate::emit_feature_err;
+use syntax::feature_gate::{GateIssue, emit_feature_err};
 use syntax::parse::token;
 
 use rustc_front::print::pprust;
@@ -797,7 +797,7 @@ fn create_substs_for_ast_trait_ref<'a,'tcx>(this: &AstConv<'tcx>,
             // only with `Fn()` etc.
             if !this.tcx().sess.features.borrow().unboxed_closures && trait_def.paren_sugar {
                 emit_feature_err(&this.tcx().sess.parse_sess.span_diagnostic,
-                                 "unboxed_closures", span,
+                                 "unboxed_closures", span, GateIssue::Language,
                                  "\
                     the precise format of `Fn`-family traits' type parameters is \
                     subject to change. Use parenthetical notation (Fn(Foo, Bar) -> Baz) instead");
@@ -810,7 +810,7 @@ fn create_substs_for_ast_trait_ref<'a,'tcx>(this: &AstConv<'tcx>,
             // only with `Fn()` etc.
             if !this.tcx().sess.features.borrow().unboxed_closures && !trait_def.paren_sugar {
                 emit_feature_err(&this.tcx().sess.parse_sess.span_diagnostic,
-                                 "unboxed_closures", span,
+                                 "unboxed_closures", span, GateIssue::Language,
                                  "\
                     parenthetical notation is only stable when used with `Fn`-family traits");
             }

src/libsyntax/ext/asm.rs

@@ -51,7 +51,9 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
                        -> Box<base::MacResult+'cx> {
     if !cx.ecfg.enable_asm() {
         feature_gate::emit_feature_err(
-            &cx.parse_sess.span_diagnostic, "asm", sp, feature_gate::EXPLAIN_ASM);
+            &cx.parse_sess.span_diagnostic, "asm", sp,
+            feature_gate::GateIssue::Language,
+            feature_gate::EXPLAIN_ASM);
         return DummyResult::expr(sp);
     }
 

src/libsyntax/ext/concat_idents.rs

@@ -23,6 +23,7 @@ pub fn expand_syntax_ext<'cx>(cx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree]
         feature_gate::emit_feature_err(&cx.parse_sess.span_diagnostic,
                                        "concat_idents",
                                        sp,
+                                       feature_gate::GateIssue::Language,
                                        feature_gate::EXPLAIN_CONCAT_IDENTS);
         return base::DummyResult::expr(sp);
     }

src/libsyntax/ext/deriving/mod.rs

@@ -105,6 +105,7 @@ fn expand_derive(cx: &mut ExtCtxt,
                     feature_gate::emit_feature_err(&cx.parse_sess.span_diagnostic,
                                                    "custom_derive",
                                                    titem.span,
+                                                   feature_gate::GateIssue::Language,
                                                    feature_gate::EXPLAIN_CUSTOM_DERIVE);
                     continue;
                 }

src/libsyntax/ext/expand.rs

@@ -778,6 +778,7 @@ pub fn expand_item_mac(it: P<ast::Item>,
                             &fld.cx.parse_sess.span_diagnostic,
                             "allow_internal_unstable",
                             it.span,
+                            feature_gate::GateIssue::Language,
                             feature_gate::EXPLAIN_ALLOW_INTERNAL_UNSTABLE)
                     }
 
@@ -1469,7 +1470,8 @@ pub fn expand_type(t: P<ast::Ty>, fld: &mut MacroExpander) -> P<ast::Ty> {
                     &fld.cx.parse_sess.span_diagnostic,
                     "type_macros",
                     t.span,
-                    "type macros are experimental (see issue: #27336)");
+                    feature_gate::GateIssue::Language,
+                    "type macros are experimental");
 
                 DummyResult::raw_ty(t.span)
             }

src/libsyntax/ext/log_syntax.rs

@@ -22,6 +22,7 @@ pub fn expand_syntax_ext<'cx>(cx: &'cx mut base::ExtCtxt,
         feature_gate::emit_feature_err(&cx.parse_sess.span_diagnostic,
                                        "log_syntax",
                                        sp,
+                                       feature_gate::GateIssue::Language,
                                        feature_gate::EXPLAIN_LOG_SYNTAX);
         return base::DummyResult::any(sp);
     }

src/libsyntax/ext/trace_macros.rs

@@ -24,6 +24,7 @@ pub fn expand_trace_macros(cx: &mut ExtCtxt,
         feature_gate::emit_feature_err(&cx.parse_sess.span_diagnostic,
                                        "trace_macros",
                                        sp,
+                                       feature_gate::GateIssue::Language,
                                        feature_gate::EXPLAIN_TRACE_MACROS);
         return base::DummyResult::any(sp);
     }