Clearer Error Message for Duplicate Definition

Clearer use of the error message and span labels to communicate
duplicaiton defitions/imports.

New error format:

```
error[E0428]: the name `Foo` is defined twice
 --> example.rs:2:1
  |
1 | trait Foo { }
  | ------------- previous definition of the trait `Foo` here
2 | struct Foo { }
  | ^^^^^^^^^^^^^^ `Foo` redefined here
  = note: `Foo` must be defined only once in the type namespace of this module

error: aborting due to previous error
```

34 files changed, 136 insertions, 109 deletions

diff --git a/src/test/compile-fail/E0254.rs b/src/test/compile-fail/E0254.rs
index bc17a46a017..89227f6b010 100644
--- a/src/test/compile-fail/E0254.rs
+++ b/src/test/compile-fail/E0254.rs
@@ -11,7 +11,7 @@
 #![feature(alloc)]
 
 extern crate alloc;
-//~^ NOTE previous import of `alloc` here
+//~^ NOTE previous import of the extern crate `alloc` here
 
 mod foo {
     pub trait alloc {
@@ -21,6 +21,7 @@ mod foo {
 
 use foo::alloc;
 //~^ ERROR E0254
-//~| NOTE already imported
+//~| NOTE `alloc` reimported here
+//~| NOTE `alloc` must be defined only once in the type namespace of this module
 
 fn main() {}
diff --git a/src/test/compile-fail/E0259.rs b/src/test/compile-fail/E0259.rs
index 259d67fe7cd..60bcd2ae076 100644
--- a/src/test/compile-fail/E0259.rs
+++ b/src/test/compile-fail/E0259.rs
@@ -11,10 +11,11 @@
 #![feature(alloc, libc)]
 
 extern crate alloc;
-//~^ NOTE previous import of `alloc` here
+//~^ NOTE previous import of the extern crate `alloc` here
 
 extern crate libc as alloc;
 //~^ ERROR E0259
-//~| NOTE `alloc` already imported
+//~| NOTE `alloc` reimported here
+//~| NOTE `alloc` must be defined only once in the type namespace of this module
 
 fn main() {}
diff --git a/src/test/compile-fail/E0260.rs b/src/test/compile-fail/E0260.rs
index 08d78782e4c..5e802bbbe3d 100644
--- a/src/test/compile-fail/E0260.rs
+++ b/src/test/compile-fail/E0260.rs
@@ -11,11 +11,12 @@
 #![feature(alloc)]
 
 extern crate alloc;
-//~^ NOTE previous import of `alloc` here
+//~^ NOTE previous import of the extern crate `alloc` here
 
 mod alloc {
-//~^ ERROR `alloc` has already been imported in this module [E0260]
-//~| NOTE `alloc` already imported
+//~^ ERROR the name `alloc` is defined multiple times [E0260]
+//~| NOTE `alloc` redefined here
+//~| NOTE `alloc` must be defined only once in the type namespace of this module
     pub trait MyTrait {
         fn do_something();
     }
diff --git a/src/test/compile-fail/E0428.rs b/src/test/compile-fail/E0428.rs
index f8502140c44..4042219b5cc 100644
--- a/src/test/compile-fail/E0428.rs
+++ b/src/test/compile-fail/E0428.rs
@@ -8,9 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-struct Bar; //~ previous definition of `Bar` here
+struct Bar; //~ previous definition of the type `Bar` here
 struct Bar; //~ ERROR E0428
-            //~| NOTE already defined
+            //~| NOTE `Bar` redefined here
+            //~| NOTE `Bar` must be defined only once in the type namespace of this module
 
 fn main () {
 }
diff --git a/src/test/compile-fail/blind-item-block-item-shadow.rs b/src/test/compile-fail/blind-item-block-item-shadow.rs
index 2d53aee39e9..eeadecf627d 100644
--- a/src/test/compile-fail/blind-item-block-item-shadow.rs
+++ b/src/test/compile-fail/blind-item-block-item-shadow.rs
@@ -14,6 +14,6 @@ fn main() {
     {
         struct Bar;
         use foo::Bar;
-        //~^ ERROR a type named `Bar` has already been defined in this block
+        //~^ ERROR the name `Bar` is defined multiple times
     }
 }
diff --git a/src/test/compile-fail/blind-item-item-shadow.rs b/src/test/compile-fail/blind-item-item-shadow.rs
index e9df8868a1e..af3abe5e056 100644
--- a/src/test/compile-fail/blind-item-item-shadow.rs
+++ b/src/test/compile-fail/blind-item-item-shadow.rs
@@ -8,10 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-mod foo { pub mod foo {  } } //~ NOTE previous definition of `foo` here
+mod foo { pub mod foo {  } } //~ NOTE previous definition of the module `foo` here
 
 use foo::foo;
-//~^ ERROR a module named `foo` has already been defined in this module
-//~| `foo` already defined
+//~^ ERROR the name `foo` is defined multiple times
+//~| `foo` reimported here
+//~| NOTE `foo` must be defined only once in the type namespace of this module
 
 fn main() {}
diff --git a/src/test/compile-fail/double-import.rs b/src/test/compile-fail/double-import.rs
index bd190a6df8e..21b8ded6d93 100644
--- a/src/test/compile-fail/double-import.rs
+++ b/src/test/compile-fail/double-import.rs
@@ -19,8 +19,9 @@ mod sub2 {
     pub fn foo() {} // implementation 2
 }
 
-use sub1::foo; //~ NOTE previous import of `foo` here
-use sub2::foo; //~ ERROR a value named `foo` has already been imported in this module [E0252]
-               //~| NOTE already imported
+use sub1::foo; //~ NOTE previous import of the value `foo` here
+use sub2::foo; //~ ERROR the name `foo` is defined multiple times
+               //~| NOTE `foo` reimported here
+               //~| NOTE `foo` must be defined only once in the value namespace of this module
 
 fn main() {}
diff --git a/src/test/compile-fail/double-type-import.rs b/src/test/compile-fail/double-type-import.rs
index 760612c05ce..9629da735b0 100644
--- a/src/test/compile-fail/double-type-import.rs
+++ b/src/test/compile-fail/double-type-import.rs
@@ -11,7 +11,7 @@
 mod foo {
     pub use self::bar::X;
     use self::bar::X;
-    //~^ ERROR a type named `X` has already been imported in this module
+    //~^ ERROR the name `X` is defined multiple times
 
     mod bar {
         pub struct X;
diff --git a/src/test/compile-fail/enum-and-module-in-same-scope.rs b/src/test/compile-fail/enum-and-module-in-same-scope.rs
index 527ac7505a6..59b4d715c2d 100644
--- a/src/test/compile-fail/enum-and-module-in-same-scope.rs
+++ b/src/test/compile-fail/enum-and-module-in-same-scope.rs
@@ -8,12 +8,13 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-enum Foo { //~ NOTE previous definition of `Foo` here
+enum Foo { //~ NOTE previous definition of the type `Foo` here
     X
 }
 
-mod Foo { //~ ERROR a type named `Foo` has already been defined
-          //~| NOTE already defined
+mod Foo { //~ ERROR the name `Foo` is defined multiple times
+          //~| NOTE `Foo` redefined here
+          //~| NOTE `Foo` must be defined only once in the type namespace of this module
     pub static X: isize = 42;
     fn f() { f() } // Check that this does not result in a resolution error
 }
diff --git a/src/test/compile-fail/imports/duplicate.rs b/src/test/compile-fail/imports/duplicate.rs
index f857f018f67..4b2a64155e5 100644
--- a/src/test/compile-fail/imports/duplicate.rs
+++ b/src/test/compile-fail/imports/duplicate.rs
@@ -21,9 +21,10 @@ mod c {
 }
 
 mod d {
-    use a::foo; //~ NOTE previous import
-    use a::foo; //~ ERROR `foo` has already been imported
-                //~| NOTE already imported
+    use a::foo; //~ NOTE previous import of the value `foo` here
+    use a::foo; //~ ERROR the name `foo` is defined multiple times
+                //~| NOTE `foo` reimported here
+                //~| NOTE `foo` must be defined only once in the value namespace of this module
 }
 
 mod e {
diff --git a/src/test/compile-fail/issue-19498.rs b/src/test/compile-fail/issue-19498.rs
index 88e804fb8aa..7de16e5ecfe 100644
--- a/src/test/compile-fail/issue-19498.rs
+++ b/src/test/compile-fail/issue-19498.rs
@@ -8,16 +8,19 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use self::A; //~ NOTE previous import of `A` here
-use self::B; //~ NOTE previous import of `B` here
-mod A {} //~ ERROR a module named `A` has already been imported in this module
-//~| `A` already imported
-pub mod B {} //~ ERROR a module named `B` has already been imported in this module
-//~| `B` already imported
+use self::A; //~ NOTE previous import of the module `A` here
+use self::B; //~ NOTE previous import of the module `B` here
+mod A {} //~ ERROR the name `A` is defined multiple times
+//~| `A` redefined here
+//~| NOTE `A` must be defined only once in the type namespace of this module
+pub mod B {} //~ ERROR the name `B` is defined multiple times
+//~| `B` redefined here
+//~| NOTE `B` must be defined only once in the type namespace of this module
 mod C {
-    use C::D; //~ NOTE previous import of `D` here
-    mod D {} //~ ERROR a module named `D` has already been imported in this module
-    //~| `D` already imported
+    use C::D; //~ NOTE previous import of the module `D` here
+    mod D {} //~ ERROR the name `D` is defined multiple times
+    //~| `D` redefined here
+    //~| NOTE `D` must be defined only once in the type namespace of this module
 }
 
 fn main() {}
diff --git a/src/test/compile-fail/issue-21546.rs b/src/test/compile-fail/issue-21546.rs
index d103d45bc4c..b7dbc7c7210 100644
--- a/src/test/compile-fail/issue-21546.rs
+++ b/src/test/compile-fail/issue-21546.rs
@@ -12,60 +12,66 @@
 
 #[allow(non_snake_case)]
 mod Foo { }
-//~^ NOTE previous definition of `Foo` here
+//~^ NOTE previous definition of the module `Foo` here
 
 #[allow(dead_code)]
 struct Foo;
-//~^ ERROR a module named `Foo` has already been defined in this module
-//~| NOTE already defined
+//~^ ERROR the name `Foo` is defined multiple times
+//~| NOTE `Foo` redefined here
+//~| NOTE `Foo` must be defined only once in the type namespace of this module
 
 #[allow(non_snake_case)]
 mod Bar { }
-//~^ NOTE previous definition of `Bar` here
+//~^ NOTE previous definition of the module `Bar` here
 
 #[allow(dead_code)]
 struct Bar(i32);
-//~^ ERROR a module named `Bar` has already been defined
-//~| NOTE already defined
+//~^ ERROR the name `Bar` is defined multiple times
+//~| NOTE `Bar` redefined here
+//~| NOTE `Bar` must be defined only once in the type namespace of this module
 
 
 #[allow(dead_code)]
 struct Baz(i32);
-//~^ NOTE previous definition
+//~^ NOTE previous definition of the type `Baz` here
 
 #[allow(non_snake_case)]
 mod Baz { }
-//~^ ERROR a type named `Baz` has already been defined
-//~| NOTE already defined
+//~^ ERROR the name `Baz` is defined multiple times
+//~| NOTE `Baz` redefined here
+//~| NOTE `Baz` must be defined only once in the type namespace of this module
 
 
 #[allow(dead_code)]
 struct Qux { x: bool }
-//~^ NOTE previous definition
+//~^ NOTE previous definition of the type `Qux` here
 
 #[allow(non_snake_case)]
 mod Qux { }
-//~^ ERROR a type named `Qux` has already been defined
-//~| NOTE already defined
+//~^ ERROR the name `Qux` is defined multiple times
+//~| NOTE `Qux` redefined here
+//~| NOTE `Qux` must be defined only once in the type namespace of this module
 
 
 #[allow(dead_code)]
 struct Quux;
-//~^ NOTE previous definition
+//~^ NOTE previous definition of the type `Quux` here
 
 #[allow(non_snake_case)]
 mod Quux { }
-//~^ ERROR a type named `Quux` has already been defined
-//~| NOTE already defined
+//~^ ERROR the name `Quux` is defined multiple times
+//~| NOTE `Quux` redefined here
+//~| NOTE `Quux` must be defined only once in the type namespace of this module
 
 
 #[allow(dead_code)]
 enum Corge { A, B }
-//~^ NOTE previous definition
+//~^ NOTE previous definition of the type `Corge` here
 
 #[allow(non_snake_case)]
 mod Corge { }
-//~^ ERROR a type named `Corge` has already been defined
-//~| NOTE already defined
+//~^ ERROR the name `Corge` is defined multiple times
+//~| NOTE `Corge` redefined here
+//~| NOTE `Corge` must be defined only once in the type namespace of this module
 
 fn main() { }
diff --git a/src/test/compile-fail/issue-24081.rs b/src/test/compile-fail/issue-24081.rs
index 26bb72b862f..dc8fc01bbfc 100644
--- a/src/test/compile-fail/issue-24081.rs
+++ b/src/test/compile-fail/issue-24081.rs
@@ -8,21 +8,26 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::ops::Add; //~ NOTE previous import
-use std::ops::Sub; //~ NOTE previous import
-use std::ops::Mul; //~ NOTE previous import
-use std::ops::Div; //~ NOTE previous import
-use std::ops::Rem; //~ NOTE previous import
+use std::ops::Add; //~ NOTE previous import of the trait `Add` here
+use std::ops::Sub; //~ NOTE previous import of the trait `Sub` here
+use std::ops::Mul; //~ NOTE previous import of the trait `Mul` here
+use std::ops::Div; //~ NOTE previous import of the trait `Div` here
+use std::ops::Rem; //~ NOTE previous import of the trait `Rem` here
 
-type Add = bool; //~ ERROR a trait named `Add` has already been imported in this module
-//~| `Add` already imported
-struct Sub { x: f32 } //~ ERROR a trait named `Sub` has already been imported in this module
-//~| `Sub` already imported
-enum Mul { A, B } //~ ERROR a trait named `Mul` has already been imported in this module
-//~| `Mul` already imported
-mod Div { } //~ ERROR a trait named `Div` has already been imported in this module
-//~| `Div` already imported
-trait Rem {  } //~ ERROR a trait named `Rem` has already been imported in this module
-//~| `Rem` already imported
+type Add = bool; //~ ERROR the name `Add` is defined multiple times
+//~| `Add` redefined here
+//~| NOTE `Add` must be defined only once in the type namespace of this module
+struct Sub { x: f32 } //~ ERROR the name `Sub` is defined multiple times
+//~| `Sub` redefined here
+//~| NOTE `Sub` must be defined only once in the type namespace of this module
+enum Mul { A, B } //~ ERROR the name `Mul` is defined multiple times
+//~| `Mul` redefined here
+//~| NOTE `Mul` must be defined only once in the type namespace of this module
+mod Div { } //~ ERROR the name `Div` is defined multiple times
+//~| `Div` redefined here
+//~| NOTE `Div` must be defined only once in the type namespace of this module
+trait Rem {  } //~ ERROR the name `Rem` is defined multiple times
+//~| `Rem` redefined here
+//~| NOTE `Rem` must be defined only once in the type namespace of this module
 
 fn main() {}
diff --git a/src/test/compile-fail/issue-25396.rs b/src/test/compile-fail/issue-25396.rs
index ec77e6ebd7c..7cfcbc5471a 100644
--- a/src/test/compile-fail/issue-25396.rs
+++ b/src/test/compile-fail/issue-25396.rs
@@ -9,16 +9,16 @@
 // except according to those terms.
 
 use foo::baz;
-use bar::baz; //~ ERROR a module named `baz` has already been imported
+use bar::baz; //~ ERROR the name `baz` is defined multiple times
 
 use foo::Quux;
-use bar::Quux; //~ ERROR a trait named `Quux` has already been imported
+use bar::Quux; //~ ERROR the name `Quux` is defined multiple times
 
 use foo::blah;
-use bar::blah; //~ ERROR a type named `blah` has already been imported
+use bar::blah; //~ ERROR the name `blah` is defined multiple times
 
 use foo::WOMP;
-use bar::WOMP; //~ ERROR a value named `WOMP` has already been imported
+use bar::WOMP; //~ ERROR the name `WOMP` is defined multiple times
 
 fn main() {}
 
diff --git a/src/test/compile-fail/issue-26886.rs b/src/test/compile-fail/issue-26886.rs
index 46e82363c8b..9b195060196 100644
--- a/src/test/compile-fail/issue-26886.rs
+++ b/src/test/compile-fail/issue-26886.rs
@@ -8,12 +8,14 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::sync::{self, Arc}; //~ NOTE previous import
-                            //~^ NOTE previous import
-use std::sync::Arc; //~ ERROR a type named
-                    //~| NOTE already imported
-use std::sync; //~ ERROR a module named
-               //~| NOTE already imported
+use std::sync::{self, Arc}; //~ NOTE previous import of the type `Arc` here
+                            //~^ NOTE previous import of the module `sync` here
+use std::sync::Arc; //~ ERROR the name `Arc` is defined multiple times
+                    //~| NOTE `Arc` reimported here
+                    //~| `Arc` must be defined only once in the type namespace of this module
+use std::sync; //~ ERROR the name `sync` is defined multiple times
+               //~| NOTE `sync` reimported here
+               //~| `sync` must be defined only once in the type namespace of this module
 
 fn main() {
 }
diff --git a/src/test/compile-fail/issue-28472.rs b/src/test/compile-fail/issue-28472.rs
index ca5bd9c6717..837de8eddcf 100644
--- a/src/test/compile-fail/issue-28472.rs
+++ b/src/test/compile-fail/issue-28472.rs
@@ -13,10 +13,10 @@
 extern {
   fn foo();
 
-  pub //~ ERROR a value named `foo` has already been defined
+  pub //~ ERROR the name `foo` is defined multiple times
   fn foo();
 
-  pub //~ ERROR a value named `foo` has already been defined
+  pub //~ ERROR the name `foo` is defined multiple times
   static mut foo: u32;
 }
 
diff --git a/src/test/compile-fail/issue-3099-a.rs b/src/test/compile-fail/issue-3099-a.rs
index cc7de01b063..db60d70ca9b 100644
--- a/src/test/compile-fail/issue-3099-a.rs
+++ b/src/test/compile-fail/issue-3099-a.rs
@@ -10,6 +10,6 @@
 
 enum a { b, c }
 
-enum a { d, e } //~ ERROR a type named `a` has already been defined in this module
+enum a { d, e } //~ ERROR the name `a` is defined multiple times
 
 fn main() {}
diff --git a/src/test/compile-fail/issue-3099-b.rs b/src/test/compile-fail/issue-3099-b.rs
index ae667341022..956d2186752 100644
--- a/src/test/compile-fail/issue-3099-b.rs
+++ b/src/test/compile-fail/issue-3099-b.rs
@@ -10,6 +10,6 @@
 
 pub mod a {}
 
-pub mod a {} //~ ERROR a module named `a` has already been defined in this module
+pub mod a {} //~ ERROR the name `a` is defined multiple times
 
 fn main() {}
diff --git a/src/test/compile-fail/issue-3099.rs b/src/test/compile-fail/issue-3099.rs
index 34bc21833e5..42766533556 100644
--- a/src/test/compile-fail/issue-3099.rs
+++ b/src/test/compile-fail/issue-3099.rs
@@ -12,7 +12,7 @@ fn a(x: String) -> String {
     format!("First function with {}", x)
 }
 
-fn a(x: String, y: String) -> String { //~ ERROR a value named `a` has already been defined
+fn a(x: String, y: String) -> String { //~ ERROR the name `a` is defined multiple times
     format!("Second function with {} and {}", x, y)
 }
 
diff --git a/src/test/compile-fail/issue-6936.rs b/src/test/compile-fail/issue-6936.rs
index c8021a22995..8eb16edcbd3 100644
--- a/src/test/compile-fail/issue-6936.rs
+++ b/src/test/compile-fail/issue-6936.rs
@@ -12,17 +12,17 @@ struct T;
 
 mod t1 {
     type Foo = ::T;
-    mod Foo {} //~ ERROR: `Foo` has already been defined
+    mod Foo {} //~ ERROR the name `Foo` is defined multiple times
 }
 
 mod t2 {
     type Foo = ::T;
-    struct Foo; //~ ERROR: `Foo` has already been defined
+    struct Foo; //~ ERROR the name `Foo` is defined multiple times
 }
 
 mod t3 {
     type Foo = ::T;
-    enum Foo {} //~ ERROR: `Foo` has already been defined
+    enum Foo {} //~ ERROR the name `Foo` is defined multiple times
 }
 
 mod t4 {
@@ -32,7 +32,7 @@ mod t4 {
 
 mod t5 {
     type Bar<T> = T;
-    mod Bar {} //~ ERROR: `Bar` has already been defined
+    mod Bar {} //~ ERROR the name `Bar` is defined multiple times
 }
 
 mod t6 {
diff --git a/src/test/compile-fail/issue-7044.rs b/src/test/compile-fail/issue-7044.rs
index 06573bea13c..9b72c249356 100644
--- a/src/test/compile-fail/issue-7044.rs
+++ b/src/test/compile-fail/issue-7044.rs
@@ -9,6 +9,6 @@
 // except according to those terms.
 
 static X: isize = 0;
-struct X; //~ ERROR `X` has already been defined
+struct X; //~ ERROR the name `X` is defined multiple times
 
 fn main() {}
diff --git a/src/test/compile-fail/issue-8640.rs b/src/test/compile-fail/issue-8640.rs
index e469e05a244..c4ca3acf080 100644
--- a/src/test/compile-fail/issue-8640.rs
+++ b/src/test/compile-fail/issue-8640.rs
@@ -13,7 +13,7 @@
 mod foo {
     use baz::bar;
     mod bar {}
-    //~^ ERROR a module named `bar` has already been imported
+    //~^ ERROR the name `bar` is defined multiple times
 }
 mod baz { pub mod bar {} }
 
diff --git a/src/test/compile-fail/no-std-inject.rs b/src/test/compile-fail/no-std-inject.rs
index f2a27dc528e..f384eafa34b 100644
--- a/src/test/compile-fail/no-std-inject.rs
+++ b/src/test/compile-fail/no-std-inject.rs
@@ -10,7 +10,7 @@
 
 #![no_std]
 
-extern crate core; //~ ERROR: an extern crate named `core` has already
+extern crate core; //~ ERROR: the name `core` is defined multiple times
 extern crate std;
 
 fn main() {}
diff --git a/src/test/compile-fail/resolve-conflict-extern-crate-vs-extern-crate.rs b/src/test/compile-fail/resolve-conflict-extern-crate-vs-extern-crate.rs
index c05d0cc1b0e..87a17c0f19a 100644
--- a/src/test/compile-fail/resolve-conflict-extern-crate-vs-extern-crate.rs
+++ b/src/test/compile-fail/resolve-conflict-extern-crate-vs-extern-crate.rs
@@ -9,6 +9,6 @@
 // except according to those terms.
 
 extern crate std;
-//~^ ERROR an extern crate named `std` has already been imported
+//~^ ERROR the name `std` is defined multiple times
 
 fn main(){}
diff --git a/src/test/compile-fail/resolve-conflict-import-vs-extern-crate.rs b/src/test/compile-fail/resolve-conflict-import-vs-extern-crate.rs
index 6cbc728c03e..91cf1d35954 100644
--- a/src/test/compile-fail/resolve-conflict-import-vs-extern-crate.rs
+++ b/src/test/compile-fail/resolve-conflict-import-vs-extern-crate.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::slice as std; //~ ERROR an extern crate named `std` has already been imported
+use std::slice as std; //~ ERROR the name `std` is defined multiple times
 
 fn main() {
 }
diff --git a/src/test/compile-fail/resolve-conflict-import-vs-import.rs b/src/test/compile-fail/resolve-conflict-import-vs-import.rs
index 10afe82f2ef..8db9023310e 100644
--- a/src/test/compile-fail/resolve-conflict-import-vs-import.rs
+++ b/src/test/compile-fail/resolve-conflict-import-vs-import.rs
@@ -10,7 +10,7 @@
 
 use std::mem::transmute;
 use std::mem::transmute;
-//~^ ERROR a value named `transmute` has already been imported
+//~^ ERROR the name `transmute` is defined multiple times
 
 fn main() {
 }
diff --git a/src/test/compile-fail/resolve-conflict-item-vs-extern-crate.rs b/src/test/compile-fail/resolve-conflict-item-vs-extern-crate.rs
index b0954ee1571..b50a60d39c8 100644
--- a/src/test/compile-fail/resolve-conflict-item-vs-extern-crate.rs
+++ b/src/test/compile-fail/resolve-conflict-item-vs-extern-crate.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 fn std() {}
-mod std {}    //~ ERROR an extern crate named `std` has already been imported
+mod std {}    //~ ERROR the name `std` is defined multiple times
 
 fn main() {
 }
diff --git a/src/test/compile-fail/resolve-conflict-item-vs-import.rs b/src/test/compile-fail/resolve-conflict-item-vs-import.rs
index 2083d98e09d..c91657bb463 100644
--- a/src/test/compile-fail/resolve-conflict-item-vs-import.rs
+++ b/src/test/compile-fail/resolve-conflict-item-vs-import.rs
@@ -9,10 +9,11 @@
 // except according to those terms.
 
 use std::mem::transmute;
-//~^ NOTE previous import of `transmute` here
+//~^ NOTE previous import of the value `transmute` here
 
 fn transmute() {}
-//~^ ERROR a value named `transmute` has already been imported in this module
-//~| `transmute` already imported
+//~^ ERROR the name `transmute` is defined multiple times
+//~| `transmute` redefined here
+//~| `transmute` must be defined only once in the value namespace of this module
 fn main() {
 }
diff --git a/src/test/compile-fail/resolve-conflict-type-vs-import.rs b/src/test/compile-fail/resolve-conflict-type-vs-import.rs
index aa7e47e223f..bbb6ee622b1 100644
--- a/src/test/compile-fail/resolve-conflict-type-vs-import.rs
+++ b/src/test/compile-fail/resolve-conflict-type-vs-import.rs
@@ -11,7 +11,7 @@
 use std::slice::Iter;
 
 struct Iter;
-//~^ ERROR a type named `Iter` has already been imported in this module
+//~^ ERROR the name `Iter` is defined multiple times
 
 fn main() {
 }
diff --git a/src/test/compile-fail/trait-duplicate-methods.rs b/src/test/compile-fail/trait-duplicate-methods.rs
index 7bcab1f6ac5..b8e628dd47a 100644
--- a/src/test/compile-fail/trait-duplicate-methods.rs
+++ b/src/test/compile-fail/trait-duplicate-methods.rs
@@ -9,9 +9,10 @@
 // except according to those terms.
 
 trait Foo {
-    fn orange(&self); //~ NOTE previous definition of `orange` here
-    fn orange(&self); //~ ERROR a value named `orange` has already been defined in this trait
-                      //~| NOTE already define
+    fn orange(&self); //~ NOTE previous definition of the value `orange` here
+    fn orange(&self); //~ ERROR the name `orange` is defined multiple times
+                      //~| NOTE `orange` redefined here
+//~| NOTE `orange` must be defined only once in the value namespace of this trait
 }
 
 fn main() {}
diff --git a/src/test/compile-fail/unresolved-extern-mod-suggestion.rs b/src/test/compile-fail/unresolved-extern-mod-suggestion.rs
index cc328d8c9e9..714b73ec739 100644
--- a/src/test/compile-fail/unresolved-extern-mod-suggestion.rs
+++ b/src/test/compile-fail/unresolved-extern-mod-suggestion.rs
@@ -10,6 +10,6 @@
 
 extern crate core;
 use core;
-//~^ ERROR an extern crate named `core` has already been imported in this module
+//~^ ERROR the name `core` is defined multiple times
 
 fn main() {}
diff --git a/src/test/compile-fail/use-mod.rs b/src/test/compile-fail/use-mod.rs
index 6be878dce1f..485a75f0f91 100644
--- a/src/test/compile-fail/use-mod.rs
+++ b/src/test/compile-fail/use-mod.rs
@@ -11,12 +11,13 @@
 use foo::bar::{
     self,
 //~^ ERROR `self` import can only appear once in the list
-//~^^ NOTE previous import of `bar` here
+//~^^ NOTE previous import of the module `bar` here
     Bar,
     self
 //~^ NOTE another `self` import appears here
-//~| ERROR a module named `bar` has already been imported in this module
-//~| NOTE already imported
+//~| ERROR the name `bar` is defined multiple times
+//~| NOTE `bar` reimported here
+//~| NOTE `bar` must be defined only once in the type namespace of this module
 };
 
 use {self};
diff --git a/src/test/compile-fail/use-paths-as-items.rs b/src/test/compile-fail/use-paths-as-items.rs
index 8a10eef60e1..db69bb33ae2 100644
--- a/src/test/compile-fail/use-paths-as-items.rs
+++ b/src/test/compile-fail/use-paths-as-items.rs
@@ -14,6 +14,6 @@
 // Related issue: #25763
 
 use std::{mem, ptr};
-use std::mem; //~ ERROR has already been imported
+use std::mem; //~ ERROR the name `mem` is defined multiple times
 
 fn main() {}
diff --git a/src/test/compile-fail/variant-namespacing.rs b/src/test/compile-fail/variant-namespacing.rs
index 44e9260770e..58bfd91550e 100644
--- a/src/test/compile-fail/variant-namespacing.rs
+++ b/src/test/compile-fail/variant-namespacing.rs
@@ -32,12 +32,12 @@ const XUnit: u8 = 0;
 
 extern crate variant_namespacing;
 pub use variant_namespacing::XE::{XStruct, XTuple, XUnit};
-//~^ ERROR `XStruct` has already been defined
-//~| ERROR `XTuple` has already been defined
-//~| ERROR `XUnit` has already been defined
+//~^ ERROR the name `XStruct` is defined multiple times
+//~| ERROR the name `XTuple` is defined multiple times
+//~| ERROR the name `XUnit` is defined multiple times
 pub use E::{Struct, Tuple, Unit};
-//~^ ERROR `Struct` has already been defined
-//~| ERROR `Tuple` has already been defined
-//~| ERROR `Unit` has already been defined
+//~^ ERROR the name `Struct` is defined multiple times
+//~| ERROR the name `Tuple` is defined multiple times
+//~| ERROR the name `Unit` is defined multiple times
 
 fn main() {}