rustdoc: Emit purity to function dox for traits

Closes #3804

src/librustdoc/clean.rs

@@ -345,6 +345,7 @@ impl Clean<SelfTy> for ast::explicit_self {
 pub struct Function {
     decl: FnDecl,
     generics: Generics,
+    purity: ast::purity,
 }
 
 impl Clean<Item> for doctree::Function {
@@ -358,6 +359,7 @@ impl Clean<Item> for doctree::Function {
             inner: FunctionItem(Function {
                 decl: self.decl.clean(),
                 generics: self.generics.clean(),
+                purity: self.purity,
             }),
         }
     }

src/librustdoc/doctree.rs

@@ -107,6 +107,7 @@ pub struct Function {
     id: NodeId,
     name: Ident,
     vis: ast::visibility,
+    purity: ast::purity,
     where: Span,
     generics: ast::Generics,
 }

src/librustdoc/html/format.rs

@@ -18,6 +18,7 @@ use clean;
 use html::render::{cache_key, current_location_key};
 
 pub struct VisSpace(Option<ast::visibility>);
+pub struct PuritySpace(ast::purity);
 pub struct Method<'self>(&'self clean::SelfTy, &'self clean::FnDecl);
 
 impl fmt::Default for clean::Generics {
@@ -228,11 +229,7 @@ impl fmt::Default for clean::Type {
                     None => {}
                 }
                 write!(f.buf, "{}{}fn{}",
-                       match decl.purity {
+                       PuritySpace(decl.purity),
-                           ast::unsafe_fn => "unsafe ",
-                           ast::extern_fn => "extern ",
-                           ast::impure_fn => ""
-                       },
                        match decl.onceness {
                            ast::Once => "once ",
                            ast::Many => "",
@@ -242,11 +239,7 @@ impl fmt::Default for clean::Type {
             }
             clean::BareFunction(ref decl) => {
                 write!(f.buf, "{}{}fn{}{}",
-                       match decl.purity {
+                       PuritySpace(decl.purity),
-                           ast::unsafe_fn => "unsafe ",
-                           ast::extern_fn => "extern ",
-                           ast::impure_fn => ""
-                       },
                        match decl.abi {
                            ~"" | ~"\"Rust\"" => ~"",
                            ref s => " " + *s + " ",
@@ -362,3 +355,13 @@ impl fmt::Default for VisSpace {
         }
     }
 }
+
+impl fmt::Default for PuritySpace {
+    fn fmt(p: &PuritySpace, f: &mut fmt::Formatter) {
+        match **p {
+            ast::unsafe_fn => write!(f.buf, "unsafe "),
+            ast::extern_fn => write!(f.buf, "extern "),
+            ast::impure_fn => {}
+        }
+    }
+}

src/librustdoc/html/render.rs

@@ -32,7 +32,7 @@ use syntax::ast;
 use clean;
 use doctree;
 use fold::DocFolder;
-use html::format::{VisSpace, Method};
+use html::format::{VisSpace, Method, PuritySpace};
 use html::layout;
 use html::markdown::Markdown;
 
@@ -717,8 +717,9 @@ fn item_module(w: &mut io::Writer, cx: &Context,
 }
 
 fn item_function(w: &mut io::Writer, it: &clean::Item, f: &clean::Function) {
-    write!(w, "<pre class='fn'>{vis}fn {name}{generics}{decl}</pre>",
+    write!(w, "<pre class='fn'>{vis}{purity}fn {name}{generics}{decl}</pre>",
            vis = VisSpace(it.visibility),
+           purity = PuritySpace(f.purity),
            name = it.name.get_ref().as_slice(),
            generics = f.generics,
            decl = f.decl);

src/librustdoc/visit_ast.rs

@@ -75,7 +75,7 @@ impl RustdocVisitor {
             }
         }
 
-        fn visit_fn(item: &ast::item, fd: &ast::fn_decl, _purity: &ast::purity,
+        fn visit_fn(item: &ast::item, fd: &ast::fn_decl, purity: &ast::purity,
                      _abi: &AbiSet, gen: &ast::Generics) -> Function {
             debug!("Visiting fn");
             Function {
@@ -86,6 +86,7 @@ impl RustdocVisitor {
                 name: item.ident,
                 where: item.span,
                 generics: gen.clone(),
+                purity: *purity,
             }
         }