Auto merge of #29939 - mitaa:doc_const_fn, r=alexcrichton

fixes #27362

Author: bors

src/librustdoc/clean/inline.rs

@@ -170,12 +170,19 @@ fn build_external_function(cx: &DocContext, tcx: &ty::ctxt, did: DefId) -> clean
         ty::TyBareFn(_, ref f) => ((did, &f.sig).clean(cx), f.unsafety, f.abi),
         _ => panic!("bad function"),
     };
+
+    let constness = if csearch::is_const_fn(&tcx.sess.cstore, did) {
+        hir::Constness::Const
+    } else {
+        hir::Constness::NotConst
+    };
+
     let predicates = tcx.lookup_predicates(did);
     clean::Function {
         decl: decl,
         generics: (&t.generics, &predicates, subst::FnSpace).clean(cx),
         unsafety: style,
-        constness: hir::Constness::NotConst,
+        constness: constness,
         abi: abi,
     }
 }
@@ -345,9 +352,15 @@ pub fn build_impl(cx: &DocContext,
                     clean::TyMethodItem(clean::TyMethod {
                         unsafety, decl, self_, generics, abi
                     }) => {
+                        let constness = if csearch::is_const_fn(&tcx.sess.cstore, did) {
+                            hir::Constness::Const
+                        } else {
+                            hir::Constness::NotConst
+                        };
+
                         clean::MethodItem(clean::Method {
                             unsafety: unsafety,
-                            constness: hir::Constness::NotConst,
+                            constness: constness,
                             decl: decl,
                             self_: self_,
                             generics: generics,

src/librustdoc/html/render.rs

@@ -1829,12 +1829,12 @@ 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 {
-    try!(write!(w, "<pre class='rust fn'>{vis}{unsafety}{abi}{constness}fn \
+    try!(write!(w, "<pre class='rust fn'>{vis}{constness}{unsafety}{abi}fn \
                     {name}{generics}{decl}{where_clause}</pre>",
            vis = VisSpace(it.visibility),
+           constness = ConstnessSpace(f.constness),
            unsafety = UnsafetySpace(f.unsafety),
            abi = AbiSpace(f.abi),
-           constness = ConstnessSpace(f.constness),
            name = it.name.as_ref().unwrap(),
            generics = f.generics,
            where_clause = WhereClause(&f.generics),
@@ -2055,8 +2055,8 @@ fn render_assoc_item(w: &mut fmt::Formatter, meth: &clean::Item,
         };
         write!(w, "{}{}{}fn <a href='{href}' class='fnname'>{name}</a>\
                    {generics}{decl}{where_clause}",
-               UnsafetySpace(unsafety),
                ConstnessSpace(constness),
+               UnsafetySpace(unsafety),
                match abi {
                    Abi::Rust => String::new(),
                    a => format!("extern {} ", a.to_string())

src/test/auxiliary/issue-27362.rs

@@ -0,0 +1,20 @@
+// Copyright 2015 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)]
+
+pub const fn foo() {}
+pub const unsafe fn bar() {}
+
+pub struct Foo;
+
+impl Foo {
+    pub const unsafe fn baz() {}
+}

src/test/rustdoc/issue-27362.rs

@@ -0,0 +1,19 @@
+// Copyright 2015 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.
+
+// aux-build:issue-27362.rs
+// ignore-cross-compile
+
+extern crate issue_27362;
+pub use issue_27362 as quux;
+
+// @matches issue_27362/quux/fn.foo.html '//pre' "pub const fn foo()"
+// @matches issue_27362/quux/fn.bar.html '//pre' "pub const unsafe fn bar()"
+// @matches issue_27362/quux/struct.Foo.html '//code' "const unsafe fn baz()"