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.

Author: bors

src/compiletest/common.rs

@@ -10,8 +10,6 @@
 
 use core::prelude::*;
 
-use cmp;
-
 #[deriving_eq]
 pub enum mode {
     mode_compile_fail,

src/compiletest/compiletest.rc

@@ -32,7 +32,6 @@ pub mod errors;
 use std::getopts;
 use std::test;
 
-use core::{result, either};
 use core::result::{Ok, Err};
 
 use common::config;

src/compiletest/errors.rs

@@ -10,8 +10,6 @@
 
 use core::prelude::*;
 
-use common::config;
-
 use core::io;
 use core::io::ReaderUtil;
 use core::str;

src/compiletest/procsrv.rs

@@ -13,14 +13,11 @@ use core::prelude::*;
 use core::io::{ReaderUtil, WriterUtil};
 use core::io;
 use core::libc::{c_int, pid_t};
-use core::libc;
 use core::os;
-use core::pipes;
 use core::run::spawn_process;
 use core::run;
 use core::str;
 use core::task;
-use core::vec;
 
 #[cfg(target_os = "win32")]
 fn target_env(lib_path: ~str, prog: ~str) -> ~[(~str,~str)] {

src/compiletest/runtest.rs

@@ -10,14 +10,12 @@
 
 use core::prelude::*;
 
-use common;
 use common::mode_run_pass;
 use common::mode_run_fail;
 use common::mode_compile_fail;
 use common::mode_pretty;
 use common::config;
 use errors;
-use header;
 use header::load_props;
 use header::TestProps;
 use procsrv;

src/compiletest/util.rs

@@ -10,12 +10,10 @@
 
 use core::prelude::*;
 
-use common;
 use common::config;
 
 use core::io;
 use core::os::getenv;
-use core::os;
 
 pub fn make_new_path(path: ~str) -> ~str {
 

src/libcore/bool.rs

@@ -11,10 +11,8 @@
 
 //! Boolean logic
 
-use bool;
-use cmp;
-use cmp::Eq;
 use option::{None, Option, Some};
+#[cfg(notest)] use cmp;
 
 /// Negation / inverse
 pub pure fn not(v: bool) -> bool { !v }
@@ -82,7 +80,7 @@ impl cmp::Eq for bool {
 #[test]
 pub fn test_bool_from_str() {
     do all_values |v| {
-        assert Some(v) == from_str(bool::to_str(v))
+        assert Some(v) == from_str(to_str(v))
     }
 }
 

src/libcore/char.rs

@@ -10,14 +10,14 @@
 
 //! Utilities for manipulating the char type
 
-use char;
-use cmp::Eq;
 use option::{None, Option, Some};
 use str;
 use u32;
 use uint;
 use unicode;
 
+#[cfg(notest)] use cmp::Eq;
+
 /*
     Lu  Uppercase_Letter    an uppercase letter
     Ll  Lowercase_Letter    a lowercase letter
@@ -305,8 +305,8 @@ fn test_to_digit() {
 
 #[test]
 fn test_is_ascii() {
-   assert str::all(~"banana", char::is_ascii);
-   assert ! str::all(~"ประเทศไทย中华Việt Nam", char::is_ascii);
+   assert str::all(~"banana", is_ascii);
+   assert ! str::all(~"ประเทศไทย中华Việt Nam", is_ascii);
 }
 
 #[test]

src/libcore/dvec.rs

@@ -20,7 +20,6 @@ Note that recursive use is not permitted.
 */
 
 use cast;
-use cast::reinterpret_cast;
 use prelude::*;
 use ptr::null;
 use vec;

src/libcore/either.rs

@@ -11,7 +11,6 @@
 //! A type that represents one of two alternatives
 
 use cmp::Eq;
-use cmp;
 use kinds::Copy;
 use result::Result;
 use result;

src/libcore/flate.rs

@@ -17,9 +17,10 @@ Simple compression
 use libc;
 use libc::{c_void, size_t, c_int};
 use ptr;
-use rand;
 use vec;
 
+#[cfg(test)] use rand;
+
 extern mod rustrt {
     unsafe fn tdefl_compress_mem_to_heap(psrc_buf: *const c_void,
                                          src_buf_len: size_t,

src/libcore/hash.rs

@@ -21,7 +21,6 @@
 
 use io;
 use io::{Writer, WriterUtil};
-use os;
 use to_bytes::IterBytes;
 use uint;
 use vec;

src/libcore/hashmap.rs

@@ -19,11 +19,8 @@ pub mod linear {
     use iter::BaseIter;
     use hash::Hash;
     use iter;
-    use kinds::Copy;
     use option::{None, Option, Some};
-    use option;
     use rand;
-    use to_bytes::IterBytes;
     use uint;
     use vec;
 

src/libcore/io.rs

@@ -16,14 +16,11 @@ Basic input/output
 
 use result::Result;
 
-use cmp::Eq;
 use dvec::DVec;
 use int;
 use libc;
 use libc::{c_int, c_long, c_uint, c_void, size_t, ssize_t};
 use libc::consts::os::posix88::*;
-use libc::consts::os::extra::*;
-use option;
 use os;
 use prelude::*;
 use ptr;
@@ -719,7 +716,9 @@ pub fn mk_file_writer(path: &Path, flags: &[FileFlag])
     -> Result<Writer, ~str> {
 
     #[cfg(windows)]
-    fn wb() -> c_int { (O_WRONLY | O_BINARY) as c_int }
+    fn wb() -> c_int {
+      (O_WRONLY | libc::consts::os::extra::O_BINARY) as c_int
+    }
 
     #[cfg(unix)]
     fn wb() -> c_int { O_WRONLY as c_int }

src/libcore/iter-trait/dlist.rs

@@ -9,8 +9,6 @@
 // except according to those terms.
 
 mod inst {
-    use cast;
-    use dlist;
     use dlist::DList;
     use managed;
     use option::{Option, Some};

src/libcore/libc.rs

@@ -1007,7 +1007,6 @@ pub mod funcs {
 
     pub mod c95 {
         use libc::types::common::c95::{FILE, c_void, fpos_t};
-        use libc::types::common::posix88::dirent_t;
         use libc::types::os::arch::c95::{c_char, c_double, c_int, c_long};
         use libc::types::os::arch::c95::{c_uint, c_ulong, c_void, size_t};
 

src/libcore/logging.rs

@@ -10,11 +10,7 @@
 
 //! Logging
 
-use cast::transmute;
-use io;
 use libc;
-use repr;
-use vec;
 
 #[nolink]
 extern mod rustrt {
@@ -48,6 +44,11 @@ pub fn console_off() {
 #[cfg(notest)]
 #[lang="log_type"]
 pub fn log_type<T>(level: u32, object: &T) {
+    use cast::transmute;
+    use io;
+    use repr;
+    use vec;
+
     let bytes = do io::with_bytes_writer |writer| {
         repr::write_repr(writer, object);
     };

src/libcore/managed.rs

@@ -10,12 +10,9 @@
 
 //! Operations on managed box types
 
-use cast::transmute;
-use cmp::{Eq, Ord};
-use managed::raw::BoxRepr;
-use prelude::*;
 use ptr;
 
+#[cfg(notest)] use cmp::{Eq, Ord};
 
 pub mod raw {
 

src/libcore/nil.rs

@@ -14,6 +14,7 @@ Functions for the unit type.
 
 */
 
+#[cfg(notest)]
 use cmp::{Eq, Ord};
 
 #[cfg(notest)]

src/libcore/num/f32.rs

@@ -11,17 +11,18 @@
 //! Operations and constants for `f32`
 
 use cmath;
-use cmp;
 use libc::{c_float, c_int};
 use num::NumCast;
 use num::strconv;
 use num;
-use ops;
 use option::Option;
 use unstable::intrinsics::floorf32;
 use from_str;
 use to_str;
 
+#[cfg(notest)] use cmp;
+#[cfg(notest)] use ops;
+
 pub use cmath::c_float_targ_consts::*;
 
 macro_rules! delegate(

src/libcore/num/f64.rs

@@ -11,18 +11,18 @@
 //! Operations and constants for `f64`
 
 use cmath;
-use cmp;
 use libc::{c_double, c_int};
-use libc;
 use num::NumCast;
 use num::strconv;
 use num;
-use ops;
 use option::Option;
 use unstable::intrinsics::floorf64;
 use to_str;
 use from_str;
 
+#[cfg(notest)] use cmp;
+#[cfg(notest)] use ops;
+
 pub use cmath::c_double_targ_consts::*;
 pub use cmp::{min, max};
 

src/libcore/num/float.rs

@@ -20,21 +20,17 @@
 
 // PORT this must match in width according to architecture
 
-use m_float = f64;
-
-use cmp::{Eq, Ord};
-use cmp;
 use f64;
 use num::NumCast;
 use num::strconv;
 use num;
-use ops;
 use option::{None, Option, Some};
-use str;
-use uint;
 use to_str;
 use from_str;
 
+#[cfg(notest)] use cmp::{Eq, Ord};
+#[cfg(notest)] use ops;
+
 pub use f64::{add, sub, mul, div, rem, lt, le, eq, ne, ge, gt};
 pub use f64::logarithm;
 pub use f64::{acos, asin, atan2, cbrt, ceil, copysign, cosh, floor};

src/libcore/num/int-template.rs

@@ -10,21 +10,15 @@
 
 use T = self::inst::T;
 
-use char;
-use cmp::{Eq, Ord};
-use cmp;
 use to_str::ToStr;
 use from_str::FromStr;
 use num::{ToStrRadix, FromStrRadix};
 use num::strconv;
 use num;
 use prelude::*;
-use str;
-use uint;
-use vec;
-use i8;
-use i16;
-use i32;
+
+#[cfg(notest)] use cmp::{Eq, Ord};
+
 pub use cmp::{min, max};
 
 pub const bits : uint = inst::bits;

src/libcore/num/num.rs

@@ -12,10 +12,7 @@
 use cmp::{Ord, Eq};
 use ops::{Add, Div, Modulo, Mul, Neg, Sub};
 use option::{None, Option, Some};
-use char;
-use str;
 use kinds::Copy;
-use vec;
 
 pub mod strconv;
 

src/libcore/num/uint-template.rs

@@ -11,22 +11,15 @@
 use T = self::inst::T;
 use T_SIGNED = self::inst::T_SIGNED;
 
-use char;
-use cmp::{Eq, Ord};
-use cmp;
 use to_str::ToStr;
 use from_str::FromStr;
 use num::{ToStrRadix, FromStrRadix};
 use num::strconv;
 use num;
 use option::{None, Option, Some};
 use prelude::*;
-use str;
-use uint;
-use vec;
-use u8;
-use u16;
-use u32;
+
+#[cfg(notest)] use cmp::{Eq, Ord};
 
 pub use cmp::{min, max};
 
@@ -357,7 +350,6 @@ pub fn to_str_radix37() {
     uint::to_str_radix(100u, 37u);
 }
 
-use io;
 #[test]
 pub fn test_ranges() {
     let mut l = ~[];