auto merge of #5179 : alexcrichton/rust/default-warn-unused-import, r=graydon

I've found that unused imports can often start cluttering a project after a long time, and it's very useful to keep them under control. I don't like how Go forces a compiler error by default and it can't be changed, but I certainly want to know about them so I think that a warn is a good default.

Now that the `unused_imports` lint option is a bit smarter, I think it's possible to change the default level to warn. This commit also removes all unused imports throughout the compiler and libraries (500+).

The only odd things that I ran into were that some `use` statements had to have `#[cfg(notest)]` or `#[cfg(test)]` based on where they were. The ones with `notest` were mostly in core for modules like `cmp` whereas `cfg(test)` was for tests that weren't part of a normal `mod test` module. 

32 files changed, 5 insertions, 80 deletions

diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index cec35b429b4..47948cc3ead 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -13,9 +13,7 @@
 use codemap::{span, FileName, spanned};
 
 use core::cast;
-use core::cmp;
 use core::option::{None, Option, Some};
-use core::ptr;
 use core::task;
 use core::to_bytes;
 use core::to_str::ToStr;
@@ -1336,15 +1334,15 @@ pub enum inlined_item {
 
 #[cfg(test)]
 mod test {
-    use std;
-    use codemap::*;
-    use super::*;
-
     //are asts encodable?
 
     // it looks like this *will* be a compiler bug, after
     // I get deriving_eq for crates into incoming :)
     /*
+    use std;
+    use codemap::*;
+    use super::*;
+
     #[test] fn check_asts_encodable() {
         let bogus_span = span {lo:BytePos(10),
                                hi:BytePos(20),
diff --git a/src/libsyntax/ast_map.rs b/src/libsyntax/ast_map.rs
index 0627e063d97..3001fe8069c 100644
--- a/src/libsyntax/ast_map.rs
+++ b/src/libsyntax/ast_map.rs
@@ -23,11 +23,8 @@ use print::pprust;
 use visit;
 
 use core::cmp;
-use core::either;
 use core::str;
 use core::vec;
-use std::oldmap::HashMap;
-use std::oldmap;
 use std;
 
 pub enum path_elt {
diff --git a/src/libsyntax/ast_util.rs b/src/libsyntax/ast_util.rs
index 96f4dadb3db..b5ccef8eae0 100644
--- a/src/libsyntax/ast_util.rs
+++ b/src/libsyntax/ast_util.rs
@@ -18,7 +18,6 @@ use parse::token;
 use visit;
 use opt_vec;
 
-use core::cmp;
 use core::int;
 use core::option;
 use core::str;
diff --git a/src/libsyntax/attr.rs b/src/libsyntax/attr.rs
index e744d19b965..7739a862432 100644
--- a/src/libsyntax/attr.rs
+++ b/src/libsyntax/attr.rs
@@ -21,8 +21,6 @@ use parse::comments::{doc_comment_style, strip_doc_comment_decoration};
 
 use core::cmp;
 use core::either::Either;
-use core::either;
-use core::option;
 use core::vec;
 use core::hashmap::linear::LinearSet;
 use std;
diff --git a/src/libsyntax/codemap.rs b/src/libsyntax/codemap.rs
index 77fe53f5b25..232c57eb5a2 100644
--- a/src/libsyntax/codemap.rs
+++ b/src/libsyntax/codemap.rs
@@ -28,7 +28,6 @@ use core::dvec::DVec;
 use core::str;
 use core::to_bytes;
 use core::uint;
-use core::vec;
 use std::serialize::{Encodable, Decodable, Encoder, Decoder};
 
 pub trait Pos {
diff --git a/src/libsyntax/diagnostic.rs b/src/libsyntax/diagnostic.rs
index ba4ec7fb6db..a83dfa5538d 100644
--- a/src/libsyntax/diagnostic.rs
+++ b/src/libsyntax/diagnostic.rs
@@ -13,7 +13,6 @@ use core::prelude::*;
 use codemap::{Pos, span};
 use codemap;
 
-use core::cmp;
 use core::io::WriterUtil;
 use core::io;
 use core::option;
diff --git a/src/libsyntax/ext/auto_encode.rs b/src/libsyntax/ext/auto_encode.rs
index b0dcdf2e664..644afaff37c 100644
--- a/src/libsyntax/ext/auto_encode.rs
+++ b/src/libsyntax/ext/auto_encode.rs
@@ -102,8 +102,6 @@ use opt_vec::OptVec;
 use ext::build;
 
 use core::vec;
-use std::oldmap;
-use std::oldmap::HashMap;
 
 // Transitional reexports so qquote can find the paths it is looking for
 mod syntax {
@@ -1208,14 +1206,7 @@ fn mk_enum_deser_body(
 mod test {
     use std::serialize::Encodable;
     use std::serialize::Encoder;
-    use core::dvec::*;
     use util::testing::*;
-    use core::io;
-    use core::str;
-    use core::option::Option;
-    use core::option::Some;
-    use core::option::None;
-    use std;
 
     // just adding the ones I want to test, for now:
     #[deriving_eq]
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 01439fb40fb..23cabc09946 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -19,7 +19,6 @@ use ext;
 use parse;
 use parse::{parser, token};
 
-use core::io;
 use core::vec;
 use core::hashmap::linear::LinearMap;
 
@@ -504,7 +503,6 @@ impl <K: Eq + Hash + IterBytes ,V: Copy> MapChain<K,V>{
 
 #[cfg(test)]
 mod test {
-    use super::*;
     use super::MapChain;
     use util::testing::check_equal;
     use core::hashmap::linear::LinearMap;
diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs
index c6e6e677348..a42564ff2ec 100644
--- a/src/libsyntax/ext/build.rs
+++ b/src/libsyntax/ext/build.rs
@@ -16,10 +16,8 @@ use codemap::span;
 use ext::base::ext_ctxt;
 use ext::build;
 
-use opt_vec;
 use opt_vec::OptVec;
 
-use core::dvec;
 use core::option;
 
 pub struct Field {
diff --git a/src/libsyntax/ext/deriving.rs b/src/libsyntax/ext/deriving.rs
index f5dbf269138..07896236442 100644
--- a/src/libsyntax/ext/deriving.rs
+++ b/src/libsyntax/ext/deriving.rs
@@ -28,7 +28,6 @@ use codemap::{span, spanned};
 use parse::token::special_idents::clownshoes_extensions;
 use ast_util;
 use opt_vec;
-use opt_vec::OptVec;
 
 use core::dvec;
 use core::uint;
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 858ce4b17a3..97c75e65e1d 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -24,7 +24,6 @@ use parse::{parser, parse_item_from_source_str, new_parser_from_tts};
 
 use core::option;
 use core::vec;
-use core::hashmap::LinearMap;
 
 pub fn expand_expr(extsbox: @mut SyntaxEnv,
                    cx: ext_ctxt,
diff --git a/src/libsyntax/ext/pipes/ast_builder.rs b/src/libsyntax/ext/pipes/ast_builder.rs
index 3b885b7a7b9..e6f0cdde8c1 100644
--- a/src/libsyntax/ext/pipes/ast_builder.rs
+++ b/src/libsyntax/ext/pipes/ast_builder.rs
@@ -17,9 +17,7 @@ use core::prelude::*;
 
 use ast::{ident, node_id};
 use ast;
-use ast_util::{ident_to_path};
 use ast_util;
-use attr;
 use codemap::{span, respan, dummy_sp, spanned};
 use codemap;
 use ext::base::{ext_ctxt, mk_ctxt};
diff --git a/src/libsyntax/ext/pipes/mod.rs b/src/libsyntax/ext/pipes/mod.rs
index c26bfd178b0..df17c960ba2 100644
--- a/src/libsyntax/ext/pipes/mod.rs
+++ b/src/libsyntax/ext/pipes/mod.rs
@@ -44,7 +44,6 @@ FIXME (#3072) - This is still incomplete.
 */
 
 use ast;
-use ast::tt_delim;
 use codemap::span;
 use ext::base;
 use ext::base::ext_ctxt;
diff --git a/src/libsyntax/ext/pipes/parse_proto.rs b/src/libsyntax/ext/pipes/parse_proto.rs
index a5ca24c6737..0725f288949 100644
--- a/src/libsyntax/ext/pipes/parse_proto.rs
+++ b/src/libsyntax/ext/pipes/parse_proto.rs
@@ -11,7 +11,6 @@
 // Parsing pipes protocols from token trees.
 
 use ast_util;
-use ext::pipes::pipec::*;
 use ext::pipes::proto::*;
 use parse::common::SeqSep;
 use parse::parser;
diff --git a/src/libsyntax/ext/pipes/pipec.rs b/src/libsyntax/ext/pipes/pipec.rs
index 968a0e5f77e..5ea9257d583 100644
--- a/src/libsyntax/ext/pipes/pipec.rs
+++ b/src/libsyntax/ext/pipes/pipec.rs
@@ -11,19 +11,15 @@
 // A protocol compiler for Rust.
 
 use ast;
-use ast::ident;
 use codemap::{dummy_sp, spanned};
 use ext::base::ext_ctxt;
 use ext::pipes::ast_builder::{append_types, ext_ctxt_ast_builder, path};
 use ext::pipes::ast_builder::{path_global};
 use ext::pipes::proto::*;
 use ext::quote::rt::*;
-use parse::*;
-use util::interner;
 use opt_vec;
 use opt_vec::OptVec;
 
-use core::dvec::DVec;
 use core::prelude::*;
 use core::str;
 use core::to_str::ToStr;
@@ -342,7 +338,7 @@ impl gen_init for protocol {
         };
 
         cx.parse_item(fmt!("pub fn init%s() -> (client::%s, server::%s)\
-                            { use core::pipes::HasBuffer; %s }",
+                            { pub use core::pipes::HasBuffer; %s }",
                            start_state.generics.to_source(cx),
                            start_state.to_ty(cx).to_source(cx),
                            start_state.to_ty(cx).to_source(cx),
diff --git a/src/libsyntax/ext/pipes/proto.rs b/src/libsyntax/ext/pipes/proto.rs
index db5c6541e26..329b3f59b1e 100644
--- a/src/libsyntax/ext/pipes/proto.rs
+++ b/src/libsyntax/ext/pipes/proto.rs
@@ -15,7 +15,6 @@ use codemap::span;
 use ext::base::ext_ctxt;
 use ext::pipes::ast_builder::{append_types, ext_ctxt_ast_builder, path};
 
-use core::cmp;
 use core::to_str::ToStr;
 
 #[deriving_eq]
diff --git a/src/libsyntax/ext/quote.rs b/src/libsyntax/ext/quote.rs
index 7b00a5e5a4b..49d5ed1d0cc 100644
--- a/src/libsyntax/ext/quote.rs
+++ b/src/libsyntax/ext/quote.rs
@@ -9,7 +9,6 @@
 // except according to those terms.
 
 use ast;
-use attr;
 use codemap::{BytePos, Pos, span};
 use ext::base::ext_ctxt;
 use ext::base;
@@ -19,7 +18,6 @@ use parse::token;
 use parse;
 
 use core::prelude::*;
-use core::str;
 
 /**
 *
@@ -34,7 +32,6 @@ use core::str;
 
 pub mod rt {
     use ast;
-    use codemap;
     use ext::base::ext_ctxt;
     use parse;
     use print::pprust;
diff --git a/src/libsyntax/ext/trace_macros.rs b/src/libsyntax/ext/trace_macros.rs
index d7f7f7c6510..b53523f78a4 100644
--- a/src/libsyntax/ext/trace_macros.rs
+++ b/src/libsyntax/ext/trace_macros.rs
@@ -10,7 +10,6 @@
 
 use core::prelude::*;
 
-use ast::tt_delim;
 use ast;
 use codemap::span;
 use ext::base::ext_ctxt;
diff --git a/src/libsyntax/ext/tt/macro_parser.rs b/src/libsyntax/ext/tt/macro_parser.rs
index 004acd40691..0e63ea3278e 100644
--- a/src/libsyntax/ext/tt/macro_parser.rs
+++ b/src/libsyntax/ext/tt/macro_parser.rs
@@ -13,7 +13,6 @@ use ast;
 use ast::{matcher, match_tok, match_seq, match_nonterminal, ident};
 use codemap::{BytePos, mk_sp};
 use codemap;
-use parse::common::*; //resolve bug?
 use parse::lexer::*; //resolve bug?
 use parse::ParseSess;
 use parse::parser::Parser;
@@ -22,8 +21,6 @@ use parse::token;
 
 use core::dvec::DVec;
 use core::dvec;
-use core::io;
-use core::option;
 use core::option::{Option, Some, None};
 use core::str;
 use core::uint;
diff --git a/src/libsyntax/ext/tt/macro_rules.rs b/src/libsyntax/ext/tt/macro_rules.rs
index 370b838ab41..e5b7152bea2 100644
--- a/src/libsyntax/ext/tt/macro_rules.rs
+++ b/src/libsyntax/ext/tt/macro_rules.rs
@@ -26,7 +26,6 @@ use parse::token::{FAT_ARROW, SEMI, LBRACE, RBRACE, nt_matchers, nt_tt};
 use print;
 
 use core::io;
-use std::oldmap::HashMap;
 
 pub fn add_new_extension(cx: ext_ctxt, sp: span, name: ident,
                          arg: ~[ast::token_tree]) -> base::MacResult {
diff --git a/src/libsyntax/ext/tt/transcribe.rs b/src/libsyntax/ext/tt/transcribe.rs
index 443c0b40390..79264f7adf0 100644
--- a/src/libsyntax/ext/tt/transcribe.rs
+++ b/src/libsyntax/ext/tt/transcribe.rs
@@ -12,7 +12,6 @@ use core::prelude::*;
 
 use ast;
 use ast::{token_tree, tt_delim, tt_tok, tt_seq, tt_nonterminal,ident};
-use ast_util;
 use codemap::{span, dummy_sp};
 use diagnostic::span_handler;
 use ext::tt::macro_parser::{named_match, matched_seq, matched_nonterminal};
@@ -22,7 +21,6 @@ use parse::lexer::TokenAndSpan;
 use core::option;
 use core::vec;
 use std;
-use std::oldmap::HashMap;
 
 /* FIXME #2811: figure out how to have a uniquely linked stack, and change to
    `~` */
diff --git a/src/libsyntax/parse/attr.rs b/src/libsyntax/parse/attr.rs
index 824a3e6f880..bf8f03d4bf6 100644
--- a/src/libsyntax/parse/attr.rs
+++ b/src/libsyntax/parse/attr.rs
@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use core::prelude::*;
-
 use ast;
 use codemap::spanned;
 use codemap::BytePos;
@@ -17,8 +15,6 @@ use parse::common::*; //resolve bug?
 use parse::token;
 use parse::parser::Parser;
 
-use core::either::{Either, Left, Right};
-
 // a parser that can parse attributes.
 pub trait parser_attr {
     fn parse_outer_attributes(&self) -> ~[ast::attribute];
diff --git a/src/libsyntax/parse/classify.rs b/src/libsyntax/parse/classify.rs
index 64c4cb3c508..4125a0bc3b4 100644
--- a/src/libsyntax/parse/classify.rs
+++ b/src/libsyntax/parse/classify.rs
@@ -14,7 +14,6 @@
 
 use ast;
 use codemap;
-use ast_util::operator_prec;
 
 pub fn expr_requires_semi_to_be_stmt(e: @ast::expr) -> bool {
     match e.node {
diff --git a/src/libsyntax/parse/comments.rs b/src/libsyntax/parse/comments.rs
index 714ae9a0fd5..ca5c4564dd9 100644
--- a/src/libsyntax/parse/comments.rs
+++ b/src/libsyntax/parse/comments.rs
@@ -19,7 +19,6 @@ use parse::lexer::{is_line_non_doc_comment, is_block_non_doc_comment};
 use parse::lexer;
 use parse::token;
 use parse;
-use util::interner;
 
 use core::cmp;
 use core::io::ReaderUtil;
diff --git a/src/libsyntax/parse/common.rs b/src/libsyntax/parse/common.rs
index 0abec79ee5d..cdeb9b2f647 100644
--- a/src/libsyntax/parse/common.rs
+++ b/src/libsyntax/parse/common.rs
@@ -17,8 +17,6 @@ use parse::parser::Parser;
 use parse::token;
 
 use core::option::{None, Option, Some};
-use core::option;
-use std::oldmap::HashMap;
 
 use opt_vec;
 use opt_vec::OptVec;
diff --git a/src/libsyntax/parse/lexer.rs b/src/libsyntax/parse/lexer.rs
index ed71fa411c6..524f9b48dd5 100644
--- a/src/libsyntax/parse/lexer.rs
+++ b/src/libsyntax/parse/lexer.rs
@@ -11,7 +11,6 @@
 use core::prelude::*;
 
 use ast;
-use ast_util;
 use codemap::{BytePos, CharPos, CodeMap, Pos, span};
 use codemap;
 use diagnostic::span_handler;
@@ -780,7 +779,6 @@ pub mod test {
     use core::option::None;
     use diagnostic;
     use parse::token;
-    use util::interner;
     use util::testing::{check_equal, check_equal_ptr};
 
     // represents a testing reader (incl. both reader and interner)
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 887f064018f..96a8f780934 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -20,13 +20,11 @@ use parse::attr::parser_attr;
 use parse::lexer::{reader, StringReader};
 use parse::parser::Parser;
 use parse::token::{ident_interner, mk_ident_interner};
-use util::interner;
 
 use core::io;
 use core::option::{None, Option, Some};
 use core::path::Path;
 use core::result::{Err, Ok, Result};
-use core::result;
 
 pub mod lexer;
 pub mod parser;
diff --git a/src/libsyntax/parse/obsolete.rs b/src/libsyntax/parse/obsolete.rs
index 4ca7c1ec888..93d3d952cdd 100644
--- a/src/libsyntax/parse/obsolete.rs
+++ b/src/libsyntax/parse/obsolete.rs
@@ -26,8 +26,6 @@ use parse::parser::Parser;
 use parse::token::Token;
 use parse::token;
 
-use core::cmp;
-use core::option;
 use core::str;
 use core::to_bytes;
 
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 0d0d23e0cd0..dd179171fce 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -57,7 +57,6 @@ use ast::{unnamed_field, unsafe_blk, unsafe_fn, variant, view_item};
 use ast::{view_item_, view_item_extern_mod, view_item_use};
 use ast::{view_path, view_path_glob, view_path_list, view_path_simple};
 use ast::{visibility, vstore, vstore_box, vstore_fixed, vstore_slice};
-use ast::{vstore_uniq};
 use ast;
 use ast_util::{ident_to_path, operator_prec};
 use ast_util;
@@ -72,7 +71,6 @@ use parse::lexer::TokenAndSpan;
 use parse::obsolete::{ObsoleteClassTraits, ObsoleteModeInFnType};
 use parse::obsolete::{ObsoleteLet, ObsoleteFieldTerminator};
 use parse::obsolete::{ObsoleteMoveInit, ObsoleteBinaryMove};
-use parse::obsolete::{ObsoleteStructCtor, ObsoleteWith};
 use parse::obsolete::{ObsoleteSyntax, ObsoleteLowerCaseKindBounds};
 use parse::obsolete::{ObsoleteUnsafeBlock, ObsoleteImplSyntax};
 use parse::obsolete::{ObsoleteTraitBoundSeparator, ObsoleteMutOwnedPointer};
@@ -82,16 +80,11 @@ use parse::token::{can_begin_expr, is_ident, is_ident_or_path};
 use parse::token::{is_plain_ident, INTERPOLATED, special_idents};
 use parse::token;
 use parse::{new_sub_parser_from_file, next_node_id, ParseSess};
-use print::pprust::expr_to_str;
-use util::interner::Interner;
 use opt_vec;
 use opt_vec::OptVec;
 
-use core::cmp;
 use core::either::{Either, Left, Right};
 use core::either;
-use core::result::Result;
-use core::vec::push;
 use core::vec;
 use std::oldmap::HashMap;
 
diff --git a/src/libsyntax/print/pp.rs b/src/libsyntax/print/pp.rs
index 1dc45b1a4bd..60e6e4dc87e 100644
--- a/src/libsyntax/print/pp.rs
+++ b/src/libsyntax/print/pp.rs
@@ -10,11 +10,8 @@
 
 use core::prelude::*;
 
-use core::cmp;
-use core::dvec::DVec;
 use core::io::WriterUtil;
 use core::io;
-use core::str;
 use core::vec;
 
 /*
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index f808a3be6bb..ab65134fd00 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -13,15 +13,12 @@ use core::prelude::*;
 use ast::{RegionTyParamBound, TraitTyParamBound, required, provided};
 use ast;
 use ast_util;
-use ast_util::{operator_prec};
-use opt_vec;
 use opt_vec::OptVec;
 use attr;
 use codemap::{CodeMap, BytePos};
 use codemap;
 use diagnostic;
 use parse::classify::{expr_is_simple_block, expr_requires_semi_to_be_stmt};
-use parse::classify::{stmt_ends_with_semi};
 use parse::token::ident_interner;
 use parse::{comments, lexer, token};
 use parse;
@@ -34,7 +31,6 @@ use core::char;
 use core::dvec::DVec;
 use core::io;
 use core::option;
-use core::str::{push_str, push_char};
 use core::str;
 use core::u64;
 use core::vec;
diff --git a/src/libsyntax/visit.rs b/src/libsyntax/visit.rs
index 262754624cb..bd60be766fb 100644
--- a/src/libsyntax/visit.rs
+++ b/src/libsyntax/visit.rs
@@ -18,9 +18,6 @@ use parse;
 use opt_vec;
 use opt_vec::OptVec;
 
-use core::option;
-use core::vec;
-
 // Context-passing AST walker. Each overridden visit method has full control
 // over what happens with its node, it can do its own traversal of the node's
 // children (potentially passing in different contexts to each), call