rustc_back: move LinkerFlavor, PanicStrategy, and RelroLevel to target.

110 files changed, 240 insertions, 340 deletions

diff --git a/src/librustc/ich/impls_misc.rs b/src/librustc/ich/impls_misc.rs
index 951315fb4a8..ba22e09cb31 100644
--- a/src/librustc/ich/impls_misc.rs
+++ b/src/librustc/ich/impls_misc.rs
@@ -20,7 +20,7 @@ impl_stable_hash_for!(enum ::session::search_paths::PathKind {
     All
 });
 
-impl_stable_hash_for!(enum ::rustc_back::PanicStrategy {
+impl_stable_hash_for!(enum ::rustc_back::target::PanicStrategy {
     Abort,
     Unwind
 });
diff --git a/src/librustc/middle/dependency_format.rs b/src/librustc/middle/dependency_format.rs
index e7fc8d633c8..3b005689ca4 100644
--- a/src/librustc/middle/dependency_format.rs
+++ b/src/librustc/middle/dependency_format.rs
@@ -69,7 +69,7 @@ use ty::TyCtxt;
 use middle::cstore::{self, DepKind};
 use middle::cstore::LinkagePreference::{self, RequireStatic, RequireDynamic};
 use util::nodemap::FxHashMap;
-use rustc_back::PanicStrategy;
+use rustc_back::target::PanicStrategy;
 
 /// A list of dependencies for a certain crate type.
 ///
diff --git a/src/librustc/middle/weak_lang_items.rs b/src/librustc/middle/weak_lang_items.rs
index a2bceb19102..fdb804e1cce 100644
--- a/src/librustc/middle/weak_lang_items.rs
+++ b/src/librustc/middle/weak_lang_items.rs
@@ -13,7 +13,7 @@
 use session::config;
 use middle::lang_items;
 
-use rustc_back::PanicStrategy;
+use rustc_back::target::PanicStrategy;
 use syntax::ast;
 use syntax::symbol::Symbol;
 use syntax_pos::Span;
diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 456e83f4700..72dcc392980 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -22,7 +22,7 @@ use session::{early_error, early_warn, Session};
 use session::search_paths::SearchPaths;
 
 use ich::StableHashingContext;
-use rustc_back::{LinkerFlavor, PanicStrategy, RelroLevel};
+use rustc_back::target::{LinkerFlavor, PanicStrategy, RelroLevel};
 use rustc_back::target::{Target, TargetTriple};
 use rustc_data_structures::stable_hasher::ToStableHashKey;
 use lint;
@@ -770,7 +770,7 @@ macro_rules! options {
         pub const parse_sanitizer: Option<&'static str> =
             Some("one of: `address`, `leak`, `memory` or `thread`");
         pub const parse_linker_flavor: Option<&'static str> =
-            Some(::rustc_back::LinkerFlavor::one_of());
+            Some(::rustc_back::target::LinkerFlavor::one_of());
         pub const parse_optimization_fuel: Option<&'static str> =
             Some("crate=integer");
         pub const parse_unpretty: Option<&'static str> =
@@ -782,7 +782,7 @@ macro_rules! options {
     #[allow(dead_code)]
     mod $mod_set {
         use super::{$struct_name, Passes, SomePasses, AllPasses, Sanitizer, Lto};
-        use rustc_back::{LinkerFlavor, PanicStrategy, RelroLevel};
+        use rustc_back::target::{LinkerFlavor, PanicStrategy, RelroLevel};
         use std::path::PathBuf;
 
         $(
@@ -2323,7 +2323,7 @@ mod dep_tracking {
     use super::{CrateType, DebugInfoLevel, ErrorOutputType, Lto, OptLevel, OutputTypes,
                 Passes, Sanitizer};
     use syntax::feature_gate::UnstableFeatures;
-    use rustc_back::{PanicStrategy, RelroLevel};
+    use rustc_back::target::{PanicStrategy, RelroLevel};
     use rustc_back::target::TargetTriple;
     use syntax::edition::Edition;
 
@@ -2456,7 +2456,7 @@ mod tests {
     use std::iter::FromIterator;
     use std::path::PathBuf;
     use super::{Externs, OutputType, OutputTypes};
-    use rustc_back::{PanicStrategy, RelroLevel};
+    use rustc_back::target::{PanicStrategy, RelroLevel};
     use syntax::symbol::Symbol;
     use syntax::edition::{Edition, DEFAULT_EDITION};
     use syntax;
diff --git a/src/librustc/session/mod.rs b/src/librustc/session/mod.rs
index 3bd2bb3c8be..e21ed9eefde 100644
--- a/src/librustc/session/mod.rs
+++ b/src/librustc/session/mod.rs
@@ -41,7 +41,7 @@ use syntax::{ast, codemap};
 use syntax::feature_gate::AttributeType;
 use syntax_pos::{MultiSpan, Span};
 
-use rustc_back::{LinkerFlavor, PanicStrategy};
+use rustc_back::target::{LinkerFlavor, PanicStrategy};
 use rustc_back::target::{Target, TargetTriple};
 use rustc_data_structures::flock;
 use jobserver::Client;
diff --git a/src/librustc/ty/maps/mod.rs b/src/librustc/ty/maps/mod.rs
index 92d23d4338f..d0783e1a4b8 100644
--- a/src/librustc/ty/maps/mod.rs
+++ b/src/librustc/ty/maps/mod.rs
@@ -45,7 +45,7 @@ use util::nodemap::{DefIdSet, DefIdMap, ItemLocalSet};
 use util::common::{profq_msg, ErrorReported, ProfileQueriesMsg};
 
 use rustc_data_structures::indexed_set::IdxSetBuf;
-use rustc_back::PanicStrategy;
+use rustc_back::target::PanicStrategy;
 use rustc_data_structures::indexed_vec::IndexVec;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::stable_hasher::StableVec;
diff --git a/src/librustc_back/lib.rs b/src/librustc_back/lib.rs
index 027a9c45555..5a2b3d31386 100644
--- a/src/librustc_back/lib.rs
+++ b/src/librustc_back/lib.rs
@@ -37,134 +37,3 @@ extern crate serialize;
 extern crate serialize as rustc_serialize; // used by deriving
 
 pub mod target;
-
-use std::str::FromStr;
-
-use serialize::json::{Json, ToJson};
-
-#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd, Hash,
-         RustcEncodable, RustcDecodable)]
-pub enum LinkerFlavor {
-    Em,
-    Gcc,
-    Ld,
-    Msvc,
-    Lld(LldFlavor),
-}
-
-#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd, Hash,
-         RustcEncodable, RustcDecodable)]
-pub enum LldFlavor {
-    Wasm,
-    Ld64,
-    Ld,
-    Link,
-}
-
-impl ToJson for LinkerFlavor {
-    fn to_json(&self) -> Json {
-        self.desc().to_json()
-    }
-}
-macro_rules! flavor_mappings {
-    ($((($($flavor:tt)*), $string:expr),)*) => (
-        impl LinkerFlavor {
-            pub const fn one_of() -> &'static str {
-                concat!("one of: ", $($string, " ",)+)
-            }
-
-            pub fn from_str(s: &str) -> Option<Self> {
-                Some(match s {
-                    $($string => $($flavor)*,)+
-                    _ => return None,
-                })
-            }
-
-            pub fn desc(&self) -> &str {
-                match *self {
-                    $($($flavor)* => $string,)+
-                }
-            }
-        }
-    )
-}
-
-
-flavor_mappings! {
-    ((LinkerFlavor::Em), "em"),
-    ((LinkerFlavor::Gcc), "gcc"),
-    ((LinkerFlavor::Ld), "ld"),
-    ((LinkerFlavor::Msvc), "msvc"),
-    ((LinkerFlavor::Lld(LldFlavor::Wasm)), "wasm-ld"),
-    ((LinkerFlavor::Lld(LldFlavor::Ld64)), "ld64.lld"),
-    ((LinkerFlavor::Lld(LldFlavor::Ld)), "ld.lld"),
-    ((LinkerFlavor::Lld(LldFlavor::Link)), "lld-link"),
-}
-
-#[derive(Clone, Copy, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]
-pub enum PanicStrategy {
-    Unwind,
-    Abort,
-}
-
-impl PanicStrategy {
-    pub fn desc(&self) -> &str {
-        match *self {
-            PanicStrategy::Unwind => "unwind",
-            PanicStrategy::Abort => "abort",
-        }
-    }
-}
-
-impl ToJson for PanicStrategy {
-    fn to_json(&self) -> Json {
-        match *self {
-            PanicStrategy::Abort => "abort".to_json(),
-            PanicStrategy::Unwind => "unwind".to_json(),
-        }
-    }
-}
-
-#[derive(Clone, Copy, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]
-pub enum RelroLevel {
-    Full,
-    Partial,
-    Off,
-    None,
-}
-
-impl RelroLevel {
-    pub fn desc(&self) -> &str {
-        match *self {
-            RelroLevel::Full => "full",
-            RelroLevel::Partial => "partial",
-            RelroLevel::Off => "off",
-            RelroLevel::None => "none",
-        }
-    }
-}
-
-impl FromStr for RelroLevel {
-    type Err = ();
-
-    fn from_str(s: &str) -> Result<RelroLevel, ()> {
-        match s {
-            "full" => Ok(RelroLevel::Full),
-            "partial" => Ok(RelroLevel::Partial),
-            "off" => Ok(RelroLevel::Off),
-            "none" => Ok(RelroLevel::None),
-            _ => Err(()),
-        }
-    }
-}
-
-impl ToJson for RelroLevel {
-    fn to_json(&self) -> Json {
-        match *self {
-            RelroLevel::Full => "full".to_json(),
-            RelroLevel::Partial => "partial".to_json(),
-            RelroLevel::Off => "off".to_json(),
-            RelroLevel::None => "None".to_json(),
-        }
-    }
-}
diff --git a/src/librustc_back/target/aarch64_apple_ios.rs b/src/librustc_back/target/aarch64_apple_ios.rs
index cff6eb534b1..5bded7c9ff3 100644
--- a/src/librustc_back/target/aarch64_apple_ios.rs
+++ b/src/librustc_back/target/aarch64_apple_ios.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
 pub fn target() -> TargetResult {
diff --git a/src/librustc_back/target/aarch64_linux_android.rs b/src/librustc_back/target/aarch64_linux_android.rs
index 2c0d6a55ed8..38ddb3d2878 100644
--- a/src/librustc_back/target/aarch64_linux_android.rs
+++ b/src/librustc_back/target/aarch64_linux_android.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 // See https://developer.android.com/ndk/guides/abis.html#arm64-v8a
 // for target ABI requirements.
diff --git a/src/librustc_back/target/aarch64_unknown_cloudabi.rs b/src/librustc_back/target/aarch64_unknown_cloudabi.rs
index a5d0e5bf166..81de7ec529a 100644
--- a/src/librustc_back/target/aarch64_unknown_cloudabi.rs
+++ b/src/librustc_back/target/aarch64_unknown_cloudabi.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::cloudabi_base::opts();
diff --git a/src/librustc_back/target/aarch64_unknown_freebsd.rs b/src/librustc_back/target/aarch64_unknown_freebsd.rs
index 1ce8d600c03..3dc77efb8f9 100644
--- a/src/librustc_back/target/aarch64_unknown_freebsd.rs
+++ b/src/librustc_back/target/aarch64_unknown_freebsd.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::freebsd_base::opts();
diff --git a/src/librustc_back/target/aarch64_unknown_fuchsia.rs b/src/librustc_back/target/aarch64_unknown_fuchsia.rs
index 73cd9c92701..d4fc211e019 100644
--- a/src/librustc_back/target/aarch64_unknown_fuchsia.rs
+++ b/src/librustc_back/target/aarch64_unknown_fuchsia.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::fuchsia_base::opts();
diff --git a/src/librustc_back/target/aarch64_unknown_linux_gnu.rs b/src/librustc_back/target/aarch64_unknown_linux_gnu.rs
index 5c9c9a0c555..e84b4a88adb 100644
--- a/src/librustc_back/target/aarch64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/aarch64_unknown_linux_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/aarch64_unknown_linux_musl.rs b/src/librustc_back/target/aarch64_unknown_linux_musl.rs
index d39ad97bbcb..d6207ac141a 100644
--- a/src/librustc_back/target/aarch64_unknown_linux_musl.rs
+++ b/src/librustc_back/target/aarch64_unknown_linux_musl.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_musl_base::opts();
diff --git a/src/librustc_back/target/android_base.rs b/src/librustc_back/target/android_base.rs
index 3660bf7bea9..c2f7eeddcf8 100644
--- a/src/librustc_back/target/android_base.rs
+++ b/src/librustc_back/target/android_base.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::TargetOptions;
+use target::{LinkerFlavor, TargetOptions};
 
 pub fn opts() -> TargetOptions {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/apple_ios_base.rs b/src/librustc_back/target/apple_ios_base.rs
index 1895ab1eb7e..74aa955432c 100644
--- a/src/librustc_back/target/apple_ios_base.rs
+++ b/src/librustc_back/target/apple_ios_base.rs
@@ -8,10 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
 use std::io;
 use std::process::Command;
-use target::{LinkArgs, TargetOptions};
+use target::{LinkArgs, LinkerFlavor, TargetOptions};
 
 use self::Arch::*;
 
diff --git a/src/librustc_back/target/arm_linux_androideabi.rs b/src/librustc_back/target/arm_linux_androideabi.rs
index ba21b1df032..535b15f246c 100644
--- a/src/librustc_back/target/arm_linux_androideabi.rs
+++ b/src/librustc_back/target/arm_linux_androideabi.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::android_base::opts();
diff --git a/src/librustc_back/target/arm_unknown_linux_gnueabi.rs b/src/librustc_back/target/arm_unknown_linux_gnueabi.rs
index e630376a67d..6a734d643fc 100644
--- a/src/librustc_back/target/arm_unknown_linux_gnueabi.rs
+++ b/src/librustc_back/target/arm_unknown_linux_gnueabi.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs b/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs
index 178a948b2b9..055fef0760d 100644
--- a/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs
+++ b/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/arm_unknown_linux_musleabi.rs b/src/librustc_back/target/arm_unknown_linux_musleabi.rs
index 29720ec5efc..d20daa7fb37 100644
--- a/src/librustc_back/target/arm_unknown_linux_musleabi.rs
+++ b/src/librustc_back/target/arm_unknown_linux_musleabi.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_musl_base::opts();
diff --git a/src/librustc_back/target/arm_unknown_linux_musleabihf.rs b/src/librustc_back/target/arm_unknown_linux_musleabihf.rs
index fc8313877f6..6d11181e898 100644
--- a/src/librustc_back/target/arm_unknown_linux_musleabihf.rs
+++ b/src/librustc_back/target/arm_unknown_linux_musleabihf.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_musl_base::opts();
diff --git a/src/librustc_back/target/armv4t_unknown_linux_gnueabi.rs b/src/librustc_back/target/armv4t_unknown_linux_gnueabi.rs
index 33399a78493..fce45c0cebf 100644
--- a/src/librustc_back/target/armv4t_unknown_linux_gnueabi.rs
+++ b/src/librustc_back/target/armv4t_unknown_linux_gnueabi.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let base = super::linux_base::opts();
diff --git a/src/librustc_back/target/armv5te_unknown_linux_gnueabi.rs b/src/librustc_back/target/armv5te_unknown_linux_gnueabi.rs
index 4efe66980a0..d9ceafede29 100644
--- a/src/librustc_back/target/armv5te_unknown_linux_gnueabi.rs
+++ b/src/librustc_back/target/armv5te_unknown_linux_gnueabi.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let base = super::linux_base::opts();
diff --git a/src/librustc_back/target/armv7_apple_ios.rs b/src/librustc_back/target/armv7_apple_ios.rs
index 67d3d12fb57..c3c8f27a883 100644
--- a/src/librustc_back/target/armv7_apple_ios.rs
+++ b/src/librustc_back/target/armv7_apple_ios.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
 pub fn target() -> TargetResult {
diff --git a/src/librustc_back/target/armv7_linux_androideabi.rs b/src/librustc_back/target/armv7_linux_androideabi.rs
index 9e3eec13ab7..900026d2393 100644
--- a/src/librustc_back/target/armv7_linux_androideabi.rs
+++ b/src/librustc_back/target/armv7_linux_androideabi.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 // See https://developer.android.com/ndk/guides/abis.html#v7a
 // for target ABI requirements.
diff --git a/src/librustc_back/target/armv7_unknown_cloudabi_eabihf.rs b/src/librustc_back/target/armv7_unknown_cloudabi_eabihf.rs
index fa66a35abbf..017376444ba 100644
--- a/src/librustc_back/target/armv7_unknown_cloudabi_eabihf.rs
+++ b/src/librustc_back/target/armv7_unknown_cloudabi_eabihf.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::cloudabi_base::opts();
diff --git a/src/librustc_back/target/armv7_unknown_linux_gnueabihf.rs b/src/librustc_back/target/armv7_unknown_linux_gnueabihf.rs
index 569c721473d..1353eac4a1a 100644
--- a/src/librustc_back/target/armv7_unknown_linux_gnueabihf.rs
+++ b/src/librustc_back/target/armv7_unknown_linux_gnueabihf.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let base = super::linux_base::opts();
diff --git a/src/librustc_back/target/armv7_unknown_linux_musleabihf.rs b/src/librustc_back/target/armv7_unknown_linux_musleabihf.rs
index 88f2b596751..95c27f89f42 100644
--- a/src/librustc_back/target/armv7_unknown_linux_musleabihf.rs
+++ b/src/librustc_back/target/armv7_unknown_linux_musleabihf.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     let base = super::linux_musl_base::opts();
diff --git a/src/librustc_back/target/armv7s_apple_ios.rs b/src/librustc_back/target/armv7s_apple_ios.rs
index e4cc89ab211..ea55ee0646b 100644
--- a/src/librustc_back/target/armv7s_apple_ios.rs
+++ b/src/librustc_back/target/armv7s_apple_ios.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
 pub fn target() -> TargetResult {
diff --git a/src/librustc_back/target/asmjs_unknown_emscripten.rs b/src/librustc_back/target/asmjs_unknown_emscripten.rs
index ab7df4ba1c5..e2cf714f0ea 100644
--- a/src/librustc_back/target/asmjs_unknown_emscripten.rs
+++ b/src/librustc_back/target/asmjs_unknown_emscripten.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use super::{LinkArgs, Target, TargetOptions};
+use super::{LinkArgs, LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Result<Target, String> {
     let mut args = LinkArgs::new();
diff --git a/src/librustc_back/target/cloudabi_base.rs b/src/librustc_back/target/cloudabi_base.rs
index 4cd52ebb26d..2f283cf3e40 100644
--- a/src/librustc_back/target/cloudabi_base.rs
+++ b/src/librustc_back/target/cloudabi_base.rs
@@ -8,9 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{LinkArgs, TargetOptions, RelroLevel};
-use std::default::Default;
+use target::{LinkArgs, LinkerFlavor, TargetOptions, RelroLevel};
 
 pub fn opts() -> TargetOptions {
     let mut args = LinkArgs::new();
diff --git a/src/librustc_back/target/dragonfly_base.rs b/src/librustc_back/target/dragonfly_base.rs
index 21dca99aa50..fc0fb4950e7 100644
--- a/src/librustc_back/target/dragonfly_base.rs
+++ b/src/librustc_back/target/dragonfly_base.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{LinkArgs, TargetOptions, RelroLevel};
+use target::{LinkArgs, LinkerFlavor, TargetOptions, RelroLevel};
 use std::default::Default;
 
 pub fn opts() -> TargetOptions {
diff --git a/src/librustc_back/target/freebsd_base.rs b/src/librustc_back/target/freebsd_base.rs
index 291b2276899..19f5bf3f6c4 100644
--- a/src/librustc_back/target/freebsd_base.rs
+++ b/src/librustc_back/target/freebsd_base.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{LinkArgs, TargetOptions, RelroLevel};
+use target::{LinkArgs, LinkerFlavor, TargetOptions, RelroLevel};
 use std::default::Default;
 
 pub fn opts() -> TargetOptions {
diff --git a/src/librustc_back/target/fuchsia_base.rs b/src/librustc_back/target/fuchsia_base.rs
index 63ccd21c220..1a09d16cc91 100644
--- a/src/librustc_back/target/fuchsia_base.rs
+++ b/src/librustc_back/target/fuchsia_base.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{LinkArgs, TargetOptions};
+use target::{LinkArgs, LinkerFlavor, TargetOptions};
 use std::default::Default;
 
 pub fn opts() -> TargetOptions {
diff --git a/src/librustc_back/target/i386_apple_ios.rs b/src/librustc_back/target/i386_apple_ios.rs
index 82eae1a31a9..3a17ae484af 100644
--- a/src/librustc_back/target/i386_apple_ios.rs
+++ b/src/librustc_back/target/i386_apple_ios.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
 pub fn target() -> TargetResult {
diff --git a/src/librustc_back/target/i686_apple_darwin.rs b/src/librustc_back/target/i686_apple_darwin.rs
index 14937f9aa55..0341684a359 100644
--- a/src/librustc_back/target/i686_apple_darwin.rs
+++ b/src/librustc_back/target/i686_apple_darwin.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::apple_base::opts();
diff --git a/src/librustc_back/target/i686_linux_android.rs b/src/librustc_back/target/i686_linux_android.rs
index bf27bce79ac..bbc50c7d418 100644
--- a/src/librustc_back/target/i686_linux_android.rs
+++ b/src/librustc_back/target/i686_linux_android.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 // See https://developer.android.com/ndk/guides/abis.html#x86
 // for target ABI requirements.
diff --git a/src/librustc_back/target/i686_pc_windows_gnu.rs b/src/librustc_back/target/i686_pc_windows_gnu.rs
index 5f20a620b6e..f93998ab7eb 100644
--- a/src/librustc_back/target/i686_pc_windows_gnu.rs
+++ b/src/librustc_back/target/i686_pc_windows_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::windows_base::opts();
diff --git a/src/librustc_back/target/i686_pc_windows_msvc.rs b/src/librustc_back/target/i686_pc_windows_msvc.rs
index 48cee044573..1607330f813 100644
--- a/src/librustc_back/target/i686_pc_windows_msvc.rs
+++ b/src/librustc_back/target/i686_pc_windows_msvc.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::windows_msvc_base::opts();
diff --git a/src/librustc_back/target/i686_unknown_cloudabi.rs b/src/librustc_back/target/i686_unknown_cloudabi.rs
index 69c3b298cab..511c9a78c81 100644
--- a/src/librustc_back/target/i686_unknown_cloudabi.rs
+++ b/src/librustc_back/target/i686_unknown_cloudabi.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::cloudabi_base::opts();
diff --git a/src/librustc_back/target/i686_unknown_dragonfly.rs b/src/librustc_back/target/i686_unknown_dragonfly.rs
index 891127b9d37..995f00b5a62 100644
--- a/src/librustc_back/target/i686_unknown_dragonfly.rs
+++ b/src/librustc_back/target/i686_unknown_dragonfly.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::dragonfly_base::opts();
diff --git a/src/librustc_back/target/i686_unknown_freebsd.rs b/src/librustc_back/target/i686_unknown_freebsd.rs
index 076acb8ed31..fe2044e631d 100644
--- a/src/librustc_back/target/i686_unknown_freebsd.rs
+++ b/src/librustc_back/target/i686_unknown_freebsd.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::freebsd_base::opts();
diff --git a/src/librustc_back/target/i686_unknown_haiku.rs b/src/librustc_back/target/i686_unknown_haiku.rs
index 02a15d6445c..0561138bbb1 100644
--- a/src/librustc_back/target/i686_unknown_haiku.rs
+++ b/src/librustc_back/target/i686_unknown_haiku.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::haiku_base::opts();
diff --git a/src/librustc_back/target/i686_unknown_linux_gnu.rs b/src/librustc_back/target/i686_unknown_linux_gnu.rs
index b509e019c7e..fc12d399de7 100644
--- a/src/librustc_back/target/i686_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/i686_unknown_linux_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/i686_unknown_linux_musl.rs b/src/librustc_back/target/i686_unknown_linux_musl.rs
index 99c0d4c8179..afc66650db3 100644
--- a/src/librustc_back/target/i686_unknown_linux_musl.rs
+++ b/src/librustc_back/target/i686_unknown_linux_musl.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_musl_base::opts();
diff --git a/src/librustc_back/target/i686_unknown_netbsd.rs b/src/librustc_back/target/i686_unknown_netbsd.rs
index dd21c205106..f4cee8026fd 100644
--- a/src/librustc_back/target/i686_unknown_netbsd.rs
+++ b/src/librustc_back/target/i686_unknown_netbsd.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::netbsd_base::opts();
diff --git a/src/librustc_back/target/i686_unknown_openbsd.rs b/src/librustc_back/target/i686_unknown_openbsd.rs
index 8daa5fcb88b..c3aef580a2c 100644
--- a/src/librustc_back/target/i686_unknown_openbsd.rs
+++ b/src/librustc_back/target/i686_unknown_openbsd.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::openbsd_base::opts();
diff --git a/src/librustc_back/target/l4re_base.rs b/src/librustc_back/target/l4re_base.rs
index 3b13ef01500..05e3d0b1f4f 100644
--- a/src/librustc_back/target/l4re_base.rs
+++ b/src/librustc_back/target/l4re_base.rs
@@ -8,9 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use PanicStrategy;
-use target::{LinkArgs, TargetOptions};
+use target::{LinkArgs, LinkerFlavor, PanicStrategy, TargetOptions};
 use std::default::Default;
 //use std::process::Command;
 
diff --git a/src/librustc_back/target/linux_base.rs b/src/librustc_back/target/linux_base.rs
index 52f700ac751..a993590733e 100644
--- a/src/librustc_back/target/linux_base.rs
+++ b/src/librustc_back/target/linux_base.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{LinkArgs, TargetOptions, RelroLevel};
+use target::{LinkArgs, LinkerFlavor, TargetOptions, RelroLevel};
 use std::default::Default;
 
 pub fn opts() -> TargetOptions {
diff --git a/src/librustc_back/target/linux_musl_base.rs b/src/librustc_back/target/linux_musl_base.rs
index 6e5e139715c..ec0641bb719 100644
--- a/src/librustc_back/target/linux_musl_base.rs
+++ b/src/librustc_back/target/linux_musl_base.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::TargetOptions;
+use target::{LinkerFlavor, TargetOptions};
 
 pub fn opts() -> TargetOptions {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/mips64_unknown_linux_gnuabi64.rs b/src/librustc_back/target/mips64_unknown_linux_gnuabi64.rs
index 5c3cf31b3e4..7fe7d7a79b2 100644
--- a/src/librustc_back/target/mips64_unknown_linux_gnuabi64.rs
+++ b/src/librustc_back/target/mips64_unknown_linux_gnuabi64.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     Ok(Target {
diff --git a/src/librustc_back/target/mips64el_unknown_linux_gnuabi64.rs b/src/librustc_back/target/mips64el_unknown_linux_gnuabi64.rs
index 96988388e81..097b286426c 100644
--- a/src/librustc_back/target/mips64el_unknown_linux_gnuabi64.rs
+++ b/src/librustc_back/target/mips64el_unknown_linux_gnuabi64.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     Ok(Target {
diff --git a/src/librustc_back/target/mips_unknown_linux_gnu.rs b/src/librustc_back/target/mips_unknown_linux_gnu.rs
index cffd1daed99..e7f7abe6ed8 100644
--- a/src/librustc_back/target/mips_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/mips_unknown_linux_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     Ok(Target {
diff --git a/src/librustc_back/target/mips_unknown_linux_musl.rs b/src/librustc_back/target/mips_unknown_linux_musl.rs
index 80168d4af4b..f55f9d07d37 100644
--- a/src/librustc_back/target/mips_unknown_linux_musl.rs
+++ b/src/librustc_back/target/mips_unknown_linux_musl.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_musl_base::opts();
diff --git a/src/librustc_back/target/mips_unknown_linux_uclibc.rs b/src/librustc_back/target/mips_unknown_linux_uclibc.rs
index c851cab069a..a6f13eea45b 100644
--- a/src/librustc_back/target/mips_unknown_linux_uclibc.rs
+++ b/src/librustc_back/target/mips_unknown_linux_uclibc.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     Ok(Target {
diff --git a/src/librustc_back/target/mipsel_unknown_linux_gnu.rs b/src/librustc_back/target/mipsel_unknown_linux_gnu.rs
index 555855b8f81..cb23611c72b 100644
--- a/src/librustc_back/target/mipsel_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/mipsel_unknown_linux_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     Ok(Target {
diff --git a/src/librustc_back/target/mipsel_unknown_linux_musl.rs b/src/librustc_back/target/mipsel_unknown_linux_musl.rs
index 6bef2fe2ea7..a45ce590ca6 100644
--- a/src/librustc_back/target/mipsel_unknown_linux_musl.rs
+++ b/src/librustc_back/target/mipsel_unknown_linux_musl.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_musl_base::opts();
diff --git a/src/librustc_back/target/mipsel_unknown_linux_uclibc.rs b/src/librustc_back/target/mipsel_unknown_linux_uclibc.rs
index a5dbdd11183..75c554ebd6b 100644
--- a/src/librustc_back/target/mipsel_unknown_linux_uclibc.rs
+++ b/src/librustc_back/target/mipsel_unknown_linux_uclibc.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     Ok(Target {
diff --git a/src/librustc_back/target/mod.rs b/src/librustc_back/target/mod.rs
index e46266b576e..bfee274262f 100644
--- a/src/librustc_back/target/mod.rs
+++ b/src/librustc_back/target/mod.rs
@@ -49,10 +49,9 @@ use std::collections::BTreeMap;
 use std::default::Default;
 use std::{fmt, io};
 use std::path::{Path, PathBuf};
+use std::str::FromStr;
 use syntax::abi::{Abi, lookup as lookup_abi};
 
-use {LinkerFlavor, PanicStrategy, RelroLevel};
-
 mod android_base;
 mod apple_base;
 mod apple_ios_base;
@@ -74,6 +73,133 @@ mod l4re_base;
 mod fuchsia_base;
 mod redox_base;
 
+#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd, Hash,
+         RustcEncodable, RustcDecodable)]
+pub enum LinkerFlavor {
+    Em,
+    Gcc,
+    Ld,
+    Msvc,
+    Lld(LldFlavor),
+}
+
+#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd, Hash,
+         RustcEncodable, RustcDecodable)]
+pub enum LldFlavor {
+    Wasm,
+    Ld64,
+    Ld,
+    Link,
+}
+
+impl ToJson for LinkerFlavor {
+    fn to_json(&self) -> Json {
+        self.desc().to_json()
+    }
+}
+macro_rules! flavor_mappings {
+    ($((($($flavor:tt)*), $string:expr),)*) => (
+        impl LinkerFlavor {
+            pub const fn one_of() -> &'static str {
+                concat!("one of: ", $($string, " ",)+)
+            }
+
+            pub fn from_str(s: &str) -> Option<Self> {
+                Some(match s {
+                    $($string => $($flavor)*,)+
+                    _ => return None,
+                })
+            }
+
+            pub fn desc(&self) -> &str {
+                match *self {
+                    $($($flavor)* => $string,)+
+                }
+            }
+        }
+    )
+}
+
+
+flavor_mappings! {
+    ((LinkerFlavor::Em), "em"),
+    ((LinkerFlavor::Gcc), "gcc"),
+    ((LinkerFlavor::Ld), "ld"),
+    ((LinkerFlavor::Msvc), "msvc"),
+    ((LinkerFlavor::Lld(LldFlavor::Wasm)), "wasm-ld"),
+    ((LinkerFlavor::Lld(LldFlavor::Ld64)), "ld64.lld"),
+    ((LinkerFlavor::Lld(LldFlavor::Ld)), "ld.lld"),
+    ((LinkerFlavor::Lld(LldFlavor::Link)), "lld-link"),
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]
+pub enum PanicStrategy {
+    Unwind,
+    Abort,
+}
+
+impl PanicStrategy {
+    pub fn desc(&self) -> &str {
+        match *self {
+            PanicStrategy::Unwind => "unwind",
+            PanicStrategy::Abort => "abort",
+        }
+    }
+}
+
+impl ToJson for PanicStrategy {
+    fn to_json(&self) -> Json {
+        match *self {
+            PanicStrategy::Abort => "abort".to_json(),
+            PanicStrategy::Unwind => "unwind".to_json(),
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]
+pub enum RelroLevel {
+    Full,
+    Partial,
+    Off,
+    None,
+}
+
+impl RelroLevel {
+    pub fn desc(&self) -> &str {
+        match *self {
+            RelroLevel::Full => "full",
+            RelroLevel::Partial => "partial",
+            RelroLevel::Off => "off",
+            RelroLevel::None => "none",
+        }
+    }
+}
+
+impl FromStr for RelroLevel {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<RelroLevel, ()> {
+        match s {
+            "full" => Ok(RelroLevel::Full),
+            "partial" => Ok(RelroLevel::Partial),
+            "off" => Ok(RelroLevel::Off),
+            "none" => Ok(RelroLevel::None),
+            _ => Err(()),
+        }
+    }
+}
+
+impl ToJson for RelroLevel {
+    fn to_json(&self) -> Json {
+        match *self {
+            RelroLevel::Full => "full".to_json(),
+            RelroLevel::Partial => "partial".to_json(),
+            RelroLevel::Off => "off".to_json(),
+            RelroLevel::None => "None".to_json(),
+        }
+    }
+}
+
 pub type LinkArgs = BTreeMap<LinkerFlavor, Vec<String>>;
 pub type TargetResult = Result<Target, String>;
 
diff --git a/src/librustc_back/target/msp430_none_elf.rs b/src/librustc_back/target/msp430_none_elf.rs
index 31df9be0bc3..c21161e89b9 100644
--- a/src/librustc_back/target/msp430_none_elf.rs
+++ b/src/librustc_back/target/msp430_none_elf.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use {LinkerFlavor, PanicStrategy};
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, PanicStrategy, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     Ok(Target {
diff --git a/src/librustc_back/target/netbsd_base.rs b/src/librustc_back/target/netbsd_base.rs
index 1cb31137193..397205a8afe 100644
--- a/src/librustc_back/target/netbsd_base.rs
+++ b/src/librustc_back/target/netbsd_base.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{LinkArgs, TargetOptions, RelroLevel};
+use target::{LinkArgs, LinkerFlavor, TargetOptions, RelroLevel};
 use std::default::Default;
 
 pub fn opts() -> TargetOptions {
diff --git a/src/librustc_back/target/openbsd_base.rs b/src/librustc_back/target/openbsd_base.rs
index 311e260ee3f..fda8f2feaf4 100644
--- a/src/librustc_back/target/openbsd_base.rs
+++ b/src/librustc_back/target/openbsd_base.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{LinkArgs, TargetOptions, RelroLevel};
+use target::{LinkArgs, LinkerFlavor, TargetOptions, RelroLevel};
 use std::default::Default;
 
 pub fn opts() -> TargetOptions {
diff --git a/src/librustc_back/target/powerpc64_unknown_linux_gnu.rs b/src/librustc_back/target/powerpc64_unknown_linux_gnu.rs
index 1f119c7204b..ca3b1c6d2e0 100644
--- a/src/librustc_back/target/powerpc64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/powerpc64_unknown_linux_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult, RelroLevel};
+use target::{LinkerFlavor, Target, TargetResult, RelroLevel};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/powerpc64le_unknown_linux_gnu.rs b/src/librustc_back/target/powerpc64le_unknown_linux_gnu.rs
index 13c59785d48..a8a3e49efa1 100644
--- a/src/librustc_back/target/powerpc64le_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/powerpc64le_unknown_linux_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/powerpc_unknown_linux_gnu.rs b/src/librustc_back/target/powerpc_unknown_linux_gnu.rs
index 1797126b310..f5ccf79910a 100644
--- a/src/librustc_back/target/powerpc_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/powerpc_unknown_linux_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/redox_base.rs b/src/librustc_back/target/redox_base.rs
index c7915d4de72..06a6443de38 100644
--- a/src/librustc_back/target/redox_base.rs
+++ b/src/librustc_back/target/redox_base.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{LinkArgs, TargetOptions};
+use target::{LinkArgs, LinkerFlavor, TargetOptions};
 use std::default::Default;
 
 pub fn opts() -> TargetOptions {
diff --git a/src/librustc_back/target/s390x_unknown_linux_gnu.rs b/src/librustc_back/target/s390x_unknown_linux_gnu.rs
index d96379547fb..92e6f7aba68 100644
--- a/src/librustc_back/target/s390x_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/s390x_unknown_linux_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/sparc64_unknown_linux_gnu.rs b/src/librustc_back/target/sparc64_unknown_linux_gnu.rs
index aed40e9df43..a79e314d503 100644
--- a/src/librustc_back/target/sparc64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/sparc64_unknown_linux_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/sparc64_unknown_netbsd.rs b/src/librustc_back/target/sparc64_unknown_netbsd.rs
index 483c8790945..07e1efa3063 100644
--- a/src/librustc_back/target/sparc64_unknown_netbsd.rs
+++ b/src/librustc_back/target/sparc64_unknown_netbsd.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::netbsd_base::opts();
diff --git a/src/librustc_back/target/sparcv9_sun_solaris.rs b/src/librustc_back/target/sparcv9_sun_solaris.rs
index 1d9027275db..65eb61d7dbd 100644
--- a/src/librustc_back/target/sparcv9_sun_solaris.rs
+++ b/src/librustc_back/target/sparcv9_sun_solaris.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::solaris_base::opts();
diff --git a/src/librustc_back/target/thumb_base.rs b/src/librustc_back/target/thumb_base.rs
index bb1fbfad261..9db4104607b 100644
--- a/src/librustc_back/target/thumb_base.rs
+++ b/src/librustc_back/target/thumb_base.rs
@@ -35,9 +35,8 @@
 // differentiate these targets from our other `arm(v7)-*-*-gnueabi(hf)` targets in the context of
 // build scripts / gcc flags.
 
-use PanicStrategy;
 use std::default::Default;
-use target::TargetOptions;
+use target::{PanicStrategy, TargetOptions};
 
 pub fn opts() -> TargetOptions {
     // See rust-lang/rfcs#1645 for a discussion about these defaults
diff --git a/src/librustc_back/target/thumbv6m_none_eabi.rs b/src/librustc_back/target/thumbv6m_none_eabi.rs
index d164fbf9d96..0b95573aa0c 100644
--- a/src/librustc_back/target/thumbv6m_none_eabi.rs
+++ b/src/librustc_back/target/thumbv6m_none_eabi.rs
@@ -10,8 +10,7 @@
 
 // Targets the Cortex-M0, Cortex-M0+ and Cortex-M1 processors (ARMv6-M architecture)
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     Ok(Target {
diff --git a/src/librustc_back/target/thumbv7em_none_eabi.rs b/src/librustc_back/target/thumbv7em_none_eabi.rs
index 7e66ddf7b06..0931e6261d2 100644
--- a/src/librustc_back/target/thumbv7em_none_eabi.rs
+++ b/src/librustc_back/target/thumbv7em_none_eabi.rs
@@ -19,8 +19,7 @@
 // To opt-in to hardware accelerated floating point operations, you can use, for example,
 // `-C target-feature=+vfp4` or `-C target-cpu=cortex-m4`.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     Ok(Target {
diff --git a/src/librustc_back/target/thumbv7em_none_eabihf.rs b/src/librustc_back/target/thumbv7em_none_eabihf.rs
index 31835de36d6..0b7a9bfb611 100644
--- a/src/librustc_back/target/thumbv7em_none_eabihf.rs
+++ b/src/librustc_back/target/thumbv7em_none_eabihf.rs
@@ -18,8 +18,7 @@
 //
 // To opt into double precision hardware support, use the `-C target-feature=-fp-only-sp` flag.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     Ok(Target {
diff --git a/src/librustc_back/target/thumbv7m_none_eabi.rs b/src/librustc_back/target/thumbv7m_none_eabi.rs
index 8f16ae4ea12..c35ac4b5685 100644
--- a/src/librustc_back/target/thumbv7m_none_eabi.rs
+++ b/src/librustc_back/target/thumbv7m_none_eabi.rs
@@ -10,8 +10,7 @@
 
 // Targets the Cortex-M3 processor (ARMv7-M)
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 
 pub fn target() -> TargetResult {
     Ok(Target {
diff --git a/src/librustc_back/target/wasm32_experimental_emscripten.rs b/src/librustc_back/target/wasm32_experimental_emscripten.rs
index 13dee3a5768..164df20f84f 100644
--- a/src/librustc_back/target/wasm32_experimental_emscripten.rs
+++ b/src/librustc_back/target/wasm32_experimental_emscripten.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use super::{LinkArgs, Target, TargetOptions};
+use super::{LinkArgs, LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Result<Target, String> {
     let mut post_link_args = LinkArgs::new();
diff --git a/src/librustc_back/target/wasm32_unknown_emscripten.rs b/src/librustc_back/target/wasm32_unknown_emscripten.rs
index 2770e67e30a..5077abf1e0e 100644
--- a/src/librustc_back/target/wasm32_unknown_emscripten.rs
+++ b/src/librustc_back/target/wasm32_unknown_emscripten.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use super::{LinkArgs, Target, TargetOptions};
+use super::{LinkArgs, LinkerFlavor, Target, TargetOptions};
 
 pub fn target() -> Result<Target, String> {
     let mut post_link_args = LinkArgs::new();
diff --git a/src/librustc_back/target/wasm32_unknown_unknown.rs b/src/librustc_back/target/wasm32_unknown_unknown.rs
index 1d84e137517..56170bbb869 100644
--- a/src/librustc_back/target/wasm32_unknown_unknown.rs
+++ b/src/librustc_back/target/wasm32_unknown_unknown.rs
@@ -17,8 +17,7 @@
 // (aka panic=abort by default), but otherwise this is in general a relatively
 // standard target.
 
-use {LinkerFlavor, LldFlavor};
-use super::{Target, TargetOptions, PanicStrategy};
+use super::{LldFlavor, LinkerFlavor, Target, TargetOptions, PanicStrategy};
 
 pub fn target() -> Result<Target, String> {
     let opts = TargetOptions {
diff --git a/src/librustc_back/target/windows_base.rs b/src/librustc_back/target/windows_base.rs
index 4b4fb27caa8..eac23e599b4 100644
--- a/src/librustc_back/target/windows_base.rs
+++ b/src/librustc_back/target/windows_base.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{LinkArgs, TargetOptions};
+use target::{LinkArgs, LinkerFlavor, TargetOptions};
 use std::default::Default;
 
 pub fn opts() -> TargetOptions {
diff --git a/src/librustc_back/target/windows_msvc_base.rs b/src/librustc_back/target/windows_msvc_base.rs
index fee5a0284c8..231fbdee0b5 100644
--- a/src/librustc_back/target/windows_msvc_base.rs
+++ b/src/librustc_back/target/windows_msvc_base.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{LinkArgs, TargetOptions};
+use target::{LinkArgs, LinkerFlavor, TargetOptions};
 use std::default::Default;
 
 pub fn opts() -> TargetOptions {
diff --git a/src/librustc_back/target/x86_64_apple_darwin.rs b/src/librustc_back/target/x86_64_apple_darwin.rs
index 71ac360eb99..56de517b04a 100644
--- a/src/librustc_back/target/x86_64_apple_darwin.rs
+++ b/src/librustc_back/target/x86_64_apple_darwin.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::apple_base::opts();
diff --git a/src/librustc_back/target/x86_64_apple_ios.rs b/src/librustc_back/target/x86_64_apple_ios.rs
index eed99e3784c..a7897a364d2 100644
--- a/src/librustc_back/target/x86_64_apple_ios.rs
+++ b/src/librustc_back/target/x86_64_apple_ios.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetOptions, TargetResult};
+use target::{LinkerFlavor, Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
 pub fn target() -> TargetResult {
diff --git a/src/librustc_back/target/x86_64_linux_android.rs b/src/librustc_back/target/x86_64_linux_android.rs
index 2aae7394153..1ca8ae5addd 100644
--- a/src/librustc_back/target/x86_64_linux_android.rs
+++ b/src/librustc_back/target/x86_64_linux_android.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::android_base::opts();
diff --git a/src/librustc_back/target/x86_64_pc_windows_gnu.rs b/src/librustc_back/target/x86_64_pc_windows_gnu.rs
index 70062d13638..a9c0cfc2c9c 100644
--- a/src/librustc_back/target/x86_64_pc_windows_gnu.rs
+++ b/src/librustc_back/target/x86_64_pc_windows_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::windows_base::opts();
diff --git a/src/librustc_back/target/x86_64_pc_windows_msvc.rs b/src/librustc_back/target/x86_64_pc_windows_msvc.rs
index 813d0f1bad9..2de8dcfe9cc 100644
--- a/src/librustc_back/target/x86_64_pc_windows_msvc.rs
+++ b/src/librustc_back/target/x86_64_pc_windows_msvc.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::windows_msvc_base::opts();
diff --git a/src/librustc_back/target/x86_64_rumprun_netbsd.rs b/src/librustc_back/target/x86_64_rumprun_netbsd.rs
index 3158665a2e2..77848ae8c6c 100644
--- a/src/librustc_back/target/x86_64_rumprun_netbsd.rs
+++ b/src/librustc_back/target/x86_64_rumprun_netbsd.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::netbsd_base::opts();
diff --git a/src/librustc_back/target/x86_64_sun_solaris.rs b/src/librustc_back/target/x86_64_sun_solaris.rs
index d5541385390..c208c386114 100644
--- a/src/librustc_back/target/x86_64_sun_solaris.rs
+++ b/src/librustc_back/target/x86_64_sun_solaris.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::solaris_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_bitrig.rs b/src/librustc_back/target/x86_64_unknown_bitrig.rs
index 1ea985d70ea..9d59e143712 100644
--- a/src/librustc_back/target/x86_64_unknown_bitrig.rs
+++ b/src/librustc_back/target/x86_64_unknown_bitrig.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::bitrig_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_cloudabi.rs b/src/librustc_back/target/x86_64_unknown_cloudabi.rs
index d1a9cb1cd7e..4baf8733af3 100644
--- a/src/librustc_back/target/x86_64_unknown_cloudabi.rs
+++ b/src/librustc_back/target/x86_64_unknown_cloudabi.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::cloudabi_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_dragonfly.rs b/src/librustc_back/target/x86_64_unknown_dragonfly.rs
index 56e4685fed5..c7059feab65 100644
--- a/src/librustc_back/target/x86_64_unknown_dragonfly.rs
+++ b/src/librustc_back/target/x86_64_unknown_dragonfly.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::dragonfly_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_freebsd.rs b/src/librustc_back/target/x86_64_unknown_freebsd.rs
index 3d26592530a..372587a8f2a 100644
--- a/src/librustc_back/target/x86_64_unknown_freebsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_freebsd.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::freebsd_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_fuchsia.rs b/src/librustc_back/target/x86_64_unknown_fuchsia.rs
index 6e97d53cfad..5831c898341 100644
--- a/src/librustc_back/target/x86_64_unknown_fuchsia.rs
+++ b/src/librustc_back/target/x86_64_unknown_fuchsia.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::fuchsia_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_haiku.rs b/src/librustc_back/target/x86_64_unknown_haiku.rs
index f42c480e7a1..1ba1e0097f7 100644
--- a/src/librustc_back/target/x86_64_unknown_haiku.rs
+++ b/src/librustc_back/target/x86_64_unknown_haiku.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::haiku_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_l4re_uclibc.rs b/src/librustc_back/target/x86_64_unknown_l4re_uclibc.rs
index 821a77f52f5..016e68fe0ee 100644
--- a/src/librustc_back/target/x86_64_unknown_l4re_uclibc.rs
+++ b/src/librustc_back/target/x86_64_unknown_l4re_uclibc.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::l4re_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_linux_gnu.rs b/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
index cfe80c96732..eb0f9487fca 100644
--- a/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_linux_gnux32.rs b/src/librustc_back/target/x86_64_unknown_linux_gnux32.rs
index 70382032836..5cf9a6fad89 100644
--- a/src/librustc_back/target/x86_64_unknown_linux_gnux32.rs
+++ b/src/librustc_back/target/x86_64_unknown_linux_gnux32.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_linux_musl.rs b/src/librustc_back/target/x86_64_unknown_linux_musl.rs
index 7e304748e32..77cdbc207e3 100644
--- a/src/librustc_back/target/x86_64_unknown_linux_musl.rs
+++ b/src/librustc_back/target/x86_64_unknown_linux_musl.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::linux_musl_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_netbsd.rs b/src/librustc_back/target/x86_64_unknown_netbsd.rs
index 7afb446f5dc..ed35ea11f10 100644
--- a/src/librustc_back/target/x86_64_unknown_netbsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_netbsd.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::netbsd_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_openbsd.rs b/src/librustc_back/target/x86_64_unknown_openbsd.rs
index e4bbdbec4c8..97da4d41fd0 100644
--- a/src/librustc_back/target/x86_64_unknown_openbsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_openbsd.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::openbsd_base::opts();
diff --git a/src/librustc_back/target/x86_64_unknown_redox.rs b/src/librustc_back/target/x86_64_unknown_redox.rs
index 401fa4ca2cb..3c930ac40ac 100644
--- a/src/librustc_back/target/x86_64_unknown_redox.rs
+++ b/src/librustc_back/target/x86_64_unknown_redox.rs
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use LinkerFlavor;
-use target::{Target, TargetResult};
+use target::{LinkerFlavor, Target, TargetResult};
 
 pub fn target() -> TargetResult {
     let mut base = super::redox_base::opts();
diff --git a/src/librustc_metadata/creader.rs b/src/librustc_metadata/creader.rs
index 8a18a4b5290..397605eeee2 100644
--- a/src/librustc_metadata/creader.rs
+++ b/src/librustc_metadata/creader.rs
@@ -21,7 +21,7 @@ use rustc::middle::allocator::AllocatorKind;
 use rustc::middle::cstore::DepKind;
 use rustc::session::{Session, CrateDisambiguator};
 use rustc::session::config::{Sanitizer, self};
-use rustc_back::PanicStrategy;
+use rustc_back::target::PanicStrategy;
 use rustc_back::target::TargetTriple;
 use rustc::session::search_paths::PathKind;
 use rustc::middle;
diff --git a/src/librustc_metadata/cstore.rs b/src/librustc_metadata/cstore.rs
index 8765d9d8c2b..30175907605 100644
--- a/src/librustc_metadata/cstore.rs
+++ b/src/librustc_metadata/cstore.rs
@@ -18,7 +18,7 @@ use rustc::hir::map::definitions::DefPathTable;
 use rustc::hir::svh::Svh;
 use rustc::middle::cstore::{DepKind, ExternCrate, MetadataLoader};
 use rustc::session::{Session, CrateDisambiguator};
-use rustc_back::PanicStrategy;
+use rustc_back::target::PanicStrategy;
 use rustc_data_structures::indexed_vec::IndexVec;
 use rustc::util::nodemap::{FxHashMap, NodeMap};
 
diff --git a/src/librustc_metadata/schema.rs b/src/librustc_metadata/schema.rs
index ddeb797f1be..506fefd93cf 100644
--- a/src/librustc_metadata/schema.rs
+++ b/src/librustc_metadata/schema.rs
@@ -19,7 +19,7 @@ use rustc::middle::lang_items;
 use rustc::mir;
 use rustc::session::CrateDisambiguator;
 use rustc::ty::{self, Ty, ReprOptions};
-use rustc_back::PanicStrategy;
+use rustc_back::target::PanicStrategy;
 use rustc_back::target::TargetTriple;
 
 use rustc_serialize as serialize;
diff --git a/src/librustc_mir/build/mod.rs b/src/librustc_mir/build/mod.rs
index 9b0e4c64171..216a6a23f08 100644
--- a/src/librustc_mir/build/mod.rs
+++ b/src/librustc_mir/build/mod.rs
@@ -20,7 +20,7 @@ use rustc::mir::visit::{MutVisitor, TyContext};
 use rustc::ty::{self, Ty, TyCtxt};
 use rustc::ty::subst::Substs;
 use rustc::util::nodemap::NodeMap;
-use rustc_back::PanicStrategy;
+use rustc_back::target::PanicStrategy;
 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
 use shim;
 use std::mem;
diff --git a/src/librustc_trans/back/command.rs b/src/librustc_trans/back/command.rs
index a5649e98baa..7fdf40480c7 100644
--- a/src/librustc_trans/back/command.rs
+++ b/src/librustc_trans/back/command.rs
@@ -17,7 +17,7 @@ use std::io;
 use std::mem;
 use std::process::{self, Output};
 
-use rustc_back::LldFlavor;
+use rustc_back::target::LldFlavor;
 
 #[derive(Clone)]
 pub struct Command {
diff --git a/src/librustc_trans/back/link.rs b/src/librustc_trans/back/link.rs
index 97683840172..bf80caadd75 100644
--- a/src/librustc_trans/back/link.rs
+++ b/src/librustc_trans/back/link.rs
@@ -17,7 +17,6 @@ use super::command::Command;
 use super::rpath::RPathConfig;
 use super::rpath;
 use metadata::METADATA_FILENAME;
-use rustc_back::LinkerFlavor;
 use rustc::session::config::{self, NoDebugInfo, OutputFilenames, OutputType, PrintRequest};
 use rustc::session::config::{RUST_CGU_EXT, Lto};
 use rustc::session::filesearch;
@@ -30,7 +29,7 @@ use rustc::util::common::time;
 use rustc::util::fs::fix_windows_verbatim_for_gcc;
 use rustc::hir::def_id::CrateNum;
 use tempdir::TempDir;
-use rustc_back::{PanicStrategy, RelroLevel};
+use rustc_back::target::{PanicStrategy, RelroLevel, LinkerFlavor};
 use rustc_back::target::TargetTriple;
 use rustc_data_structures::fx::FxHashSet;
 use context::get_reloc_model;
diff --git a/src/librustc_trans/back/linker.rs b/src/librustc_trans/back/linker.rs
index e001e809ee5..16716c51bc9 100644
--- a/src/librustc_trans/back/linker.rs
+++ b/src/librustc_trans/back/linker.rs
@@ -23,7 +23,7 @@ use rustc::middle::dependency_format::Linkage;
 use rustc::session::Session;
 use rustc::session::config::{self, CrateType, OptLevel, DebugInfoLevel};
 use rustc::ty::TyCtxt;
-use rustc_back::{LinkerFlavor, LldFlavor};
+use rustc_back::target::{LinkerFlavor, LldFlavor};
 use serialize::{json, Encoder};
 
 /// For all the linkers we support, and information they might
diff --git a/src/librustc_trans/callee.rs b/src/librustc_trans/callee.rs
index 2c503bdab30..c7eaa7b866f 100644
--- a/src/librustc_trans/callee.rs
+++ b/src/librustc_trans/callee.rs
@@ -26,7 +26,7 @@ use rustc::hir::def_id::DefId;
 use rustc::ty::{self, TypeFoldable};
 use rustc::ty::layout::LayoutOf;
 use rustc::ty::subst::Substs;
-use rustc_back::PanicStrategy;
+use rustc_back::target::PanicStrategy;
 
 /// Translates a reference to a fn/method item, monomorphizing and
 /// inlining as it goes.
diff --git a/src/librustc_trans/declare.rs b/src/librustc_trans/declare.rs
index c2010feb1b6..b77471fb0e6 100644
--- a/src/librustc_trans/declare.rs
+++ b/src/librustc_trans/declare.rs
@@ -24,7 +24,7 @@ use llvm::{self, ValueRef};
 use llvm::AttributePlace::Function;
 use rustc::ty::{self, Ty};
 use rustc::session::config::Sanitizer;
-use rustc_back::PanicStrategy;
+use rustc_back::target::PanicStrategy;
 use abi::{Abi, FnType};
 use attributes;
 use context::CodegenCx;
diff --git a/src/librustc_trans/type_of.rs b/src/librustc_trans/type_of.rs
index f37114ee4ac..7d7e52ecef5 100644
--- a/src/librustc_trans/type_of.rs
+++ b/src/librustc_trans/type_of.rs
@@ -13,7 +13,7 @@ use common::*;
 use rustc::hir;
 use rustc::ty::{self, Ty, TypeFoldable};
 use rustc::ty::layout::{self, Align, LayoutOf, Size, TyLayout};
-use rustc_back::PanicStrategy;
+use rustc_back::target::PanicStrategy;
 use trans_item::DefPathBasedNames;
 use type_::Type;