Rollup merge of rust-lang#44254 - GuillaumeGomez:const-fix-rustdoc, r=QuietMisdreavus

Fix rendering of const keyword for functions

Fixes rust-lang#44187.

r? @QuietMisdreavus

Author: GuillaumeGomez

src/librustdoc/html/render.rs

@@ -54,13 +54,11 @@ use externalfiles::ExternalHtml;
 
 use serialize::json::{ToJson, Json, as_json};
 use syntax::{abi, ast};
-use syntax::feature_gate::UnstableFeatures;
 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefId};
 use rustc::middle::privacy::AccessLevels;
 use rustc::middle::stability;
 use rustc::hir;
 use rustc::util::nodemap::{FxHashMap, FxHashSet};
-use rustc::session::config::nightly_options::is_nightly_build;
 use rustc_data_structures::flock;
 
 use clean::{self, AttributesExt, GetDefId, SelfTy, Mutability, Span};
@@ -2192,14 +2190,9 @@ 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 UnstableFeatures::from_environment() {
-        UnstableFeatures::Allow => f.constness,
-        _ => hir::Constness::NotConst
-    };
     let name_len = format!("{}{}{}{:#}fn {}{:#}",
                            VisSpace(&it.visibility),
-                           ConstnessSpace(vis_constness),
+                           ConstnessSpace(f.constness),
                            UnsafetySpace(f.unsafety),
                            AbiSpace(f.abi),
                            it.name.as_ref().unwrap(),
@@ -2209,7 +2202,7 @@ fn item_function(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
     write!(w, "{vis}{constness}{unsafety}{abi}fn \
                {name}{generics}{decl}{where_clause}</pre>",
            vis = VisSpace(&it.visibility),
-           constness = ConstnessSpace(vis_constness),
+           constness = ConstnessSpace(f.constness),
            unsafety = UnsafetySpace(f.unsafety),
            abi = AbiSpace(f.abi),
            name = it.name.as_ref().unwrap(),
@@ -2591,14 +2584,8 @@ fn render_assoc_item(w: &mut fmt::Formatter,
                 href(did).map(|p| format!("{}#{}.{}", p.0, ty, name)).unwrap_or(anchor)
             }
         };
-        // FIXME(#24111): remove when `const_fn` is stabilized
-        let vis_constness = if is_nightly_build() {
-            constness
-        } else {
-            hir::Constness::NotConst
-        };
         let mut head_len = format!("{}{}{:#}fn {}{:#}",
-                                   ConstnessSpace(vis_constness),
+                                   ConstnessSpace(constness),
                                    UnsafetySpace(unsafety),
                                    AbiSpace(abi),
                                    name,
@@ -2611,7 +2598,7 @@ fn render_assoc_item(w: &mut fmt::Formatter,
         };
         write!(w, "{}{}{}fn <a href='{href}' class='fnname'>{name}</a>\
                    {generics}{decl}{where_clause}",
-               ConstnessSpace(vis_constness),
+               ConstnessSpace(constness),
                UnsafetySpace(unsafety),
                AbiSpace(abi),
                href = href,

src/test/rustdoc/const-fn.rs

@@ -0,0 +1,27 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(const_fn)]
+#![crate_name = "foo"]
+
+// @has foo/fn.bar.html
+// @has - '//*[@class="rust fn"]' 'pub const fn bar() -> '
+/// foo
+pub const fn bar() -> usize {
+    2
+}
+
+// @has foo/struct.Foo.html
+// @has - '//*[@class="method"]' 'const fn new()'
+pub struct Foo(usize);
+
+impl Foo {
+    pub const fn new() -> Foo { Foo(0) }
+}