auto merge of #14696 : jakub-/rust/dead-struct-fields, r=alexcrichton

This uncovered some dead code, most notably in middle/liveness.rs, which I think suggests there must be something fishy with that part of the code.

The #[allow(dead_code)] annotations on some of the fields I am not super happy about but as I understand, marker type may disappear at some point.

src/libsyntax/ast.rs

@@ -1053,6 +1053,15 @@ pub struct StructField_ {
     pub attrs: Vec<Attribute>,
 }
 
+impl StructField_ {
+    pub fn ident(&self) -> Option<Ident> {
+        match self.kind {
+            NamedField(ref ident, _) => Some(ident.clone()),
+            UnnamedField(_) => None
+        }
+    }
+}
+
 pub type StructField = Spanned<StructField_>;
 
 #[deriving(Clone, PartialEq, Eq, Encodable, Decodable, Hash)]

src/libsyntax/ext/build.rs

@@ -21,11 +21,6 @@ use parse::token::special_idents;
 use parse::token::InternedString;
 use parse::token;
 
-pub struct Field {
-    ident: ast::Ident,
-    ex: @ast::Expr
-}
-
 // Transitional reexports so qquote can find the paths it is looking for
 mod syntax {
     pub use ext;
@@ -1000,9 +995,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
     }
 }
 
-struct Duplicator<'a> {
-    cx: &'a ExtCtxt<'a>,
-}
+struct Duplicator<'a>;
 
 impl<'a> Folder for Duplicator<'a> {
     fn new_id(&mut self, _: NodeId) -> NodeId {
@@ -1021,10 +1014,8 @@ pub trait Duplicate {
 }
 
 impl Duplicate for @ast::Expr {
-    fn duplicate(&self, cx: &ExtCtxt) -> @ast::Expr {
-        let mut folder = Duplicator {
-            cx: cx,
-        };
+    fn duplicate(&self, _: &ExtCtxt) -> @ast::Expr {
+        let mut folder = Duplicator;
         folder.fold_expr(*self)
     }
 }

src/libsyntax/print/pprust.rs

@@ -19,7 +19,6 @@ use codemap::{CodeMap, BytePos};
 use codemap;
 use diagnostic;
 use parse::classify::expr_is_simple_block;
-use parse::token::IdentInterner;
 use parse::token;
 use parse::lexer::comments;
 use parse;
@@ -30,7 +29,6 @@ use print::pp;
 use std::io::{IoResult, MemWriter};
 use std::io;
 use std::mem;
-use std::rc::Rc;
 use std::str;
 use std::string::String;
 
@@ -58,7 +56,6 @@ pub struct CurrentCommentAndLiteral {
 pub struct State<'a> {
     pub s: pp::Printer,
     cm: Option<&'a CodeMap>,
-    intr: Rc<token::IdentInterner>,
     comments: Option<Vec<comments::Comment> >,
     literals: Option<Vec<comments::Literal> >,
     cur_cmnt_and_lit: CurrentCommentAndLiteral,
@@ -76,7 +73,6 @@ pub fn rust_printer_annotated<'a>(writer: Box<io::Writer>,
     State {
         s: pp::mk_printer(writer, default_columns),
         cm: None,
-        intr: token::get_ident_interner(),
         comments: None,
         literals: None,
         cur_cmnt_and_lit: CurrentCommentAndLiteral {
@@ -111,7 +107,6 @@ pub fn print_crate<'a>(cm: &'a CodeMap,
     let mut s = State {
         s: pp::mk_printer(out, default_columns),
         cm: Some(cm),
-        intr: token::get_ident_interner(),
         comments: Some(cmnts),
         // If the code is post expansion, don't use the table of
         // literals, since it doesn't correspond with the literals