add more to the ERROR messages

src/test/ui/underscore-lifetime/in-binder.rs

@@ -10,36 +10,36 @@ struct IceCube<'a> {
 }
 
 impl<'_> IceCube<'_> {}
-//[Rust2015]~^ ERROR
-//[Rust2015]~| ERROR
-//[Rust2018]~^^^ ERROR
+//[Rust2015]~^ ERROR `'_` cannot be used here
+//[Rust2015]~| ERROR missing lifetime specifier
+//[Rust2018]~^^^ ERROR `'_` cannot be used here
 
 struct Struct<'_> {
-//[Rust2015]~^ ERROR
-//[Rust2018]~^^ ERROR
+//[Rust2015]~^ ERROR `'_` cannot be used here
+//[Rust2018]~^^ ERROR `'_` cannot be used here
     v: Vec<&'static char>
 }
 
 enum Enum<'_> {
-//[Rust2015]~^ ERROR
-//[Rust2018]~^^ ERROR
+//[Rust2015]~^ ERROR `'_` cannot be used here
+//[Rust2018]~^^ ERROR `'_` cannot be used here
     Variant
 }
 
 union Union<'_> {
-//[Rust2015]~^ ERROR
-//[Rust2018]~^^ ERROR
+//[Rust2015]~^ ERROR `'_` cannot be used here
+//[Rust2018]~^^ ERROR `'_` cannot be used here
     a: u32
 }
 
 trait Trait<'_> {
-//[Rust2015]~^ ERROR
-//[Rust2018]~^^ ERROR
+//[Rust2015]~^ ERROR `'_` cannot be used here
+//[Rust2018]~^^ ERROR `'_` cannot be used here
 }
 
 fn foo<'_>() {
-    //[Rust2015]~^ ERROR
-    //[Rust2018]~^^ ERROR
+    //[Rust2015]~^ ERROR `'_` cannot be used here
+    //[Rust2018]~^^ ERROR `'_` cannot be used here
 }
 
 fn main() {}

src/test/ui/underscore-lifetime/in-fn-return-illegal.rs

@@ -12,6 +12,6 @@
 
 use std::fmt::Debug;
 
-fn foo(x: &u32, y: &u32) -> &'_ u32 { loop { } } //~ ERROR
+fn foo(x: &u32, y: &u32) -> &'_ u32 { loop { } } //~ ERROR missing lifetime specifier
 
 fn main() { }

src/test/ui/underscore-lifetime/in-fn-return-illegal.stderr

@@ -1,7 +1,7 @@
 error[E0106]: missing lifetime specifier
   --> $DIR/in-fn-return-illegal.rs:15:30
    |
-LL | fn foo(x: &u32, y: &u32) -> &'_ u32 { loop { } } //~ ERROR
+LL | fn foo(x: &u32, y: &u32) -> &'_ u32 { loop { } } //~ ERROR missing lifetime specifier
    |                              ^^ expected lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from `x` or `y`

src/test/ui/underscore-lifetime/in-struct.rs

@@ -13,11 +13,11 @@
 use std::fmt::Debug;
 
 struct Foo {
-    x: &'_ u32, //~ ERROR
+    x: &'_ u32, //~ ERROR missing lifetime specifier
 }
 
 enum Bar {
-    Variant(&'_ u32), //~ ERROR
+    Variant(&'_ u32), //~ ERROR missing lifetime specifier
 }
 
 fn main() { }

src/test/ui/underscore-lifetime/in-struct.stderr

@@ -1,13 +1,13 @@
 error[E0106]: missing lifetime specifier
   --> $DIR/in-struct.rs:16:9
    |
-LL |     x: &'_ u32, //~ ERROR
+LL |     x: &'_ u32, //~ ERROR missing lifetime specifier
    |         ^^ expected lifetime parameter
 
 error[E0106]: missing lifetime specifier
   --> $DIR/in-struct.rs:20:14
    |
-LL |     Variant(&'_ u32), //~ ERROR
+LL |     Variant(&'_ u32), //~ ERROR missing lifetime specifier
    |              ^^ expected lifetime parameter
 
 error: aborting due to 2 previous errors

src/test/ui/underscore-lifetime/where-clause-inherent-impl-ampersand.rs

@@ -11,8 +11,8 @@ struct Foo<T> {
 impl<T> Foo<T>
 where
     T: WithType<&u32>
-//[rust2015]~^ ERROR
-//[rust2018]~^^ ERROR
+//[rust2015]~^ ERROR `&` without an explicit lifetime name cannot be used here
+//[rust2018]~^^ ERROR `&` without an explicit lifetime name cannot be used here
 { }
 
 fn main() {}

src/test/ui/underscore-lifetime/where-clause-inherent-impl-underscore.rs

@@ -11,8 +11,8 @@ struct Foo<T> {
 impl<T> Foo<T>
 where
     T: WithRegion<'_>
-//[rust2015]~^ ERROR
-//[rust2018]~^^ ERROR
+//[rust2015]~^ ERROR `'_` cannot be used here
+//[rust2018]~^^ ERROR `'_` cannot be used here
 { }
 
 fn main() {}

src/test/ui/underscore-lifetime/where-clause-trait-impl-region.rs

@@ -9,8 +9,8 @@ trait Foo { }
 impl<T> Foo for Vec<T>
 where
     T: WithType<&u32>
-//[rust2015]~^ ERROR
-//[rust2018]~^^ ERROR
+//[rust2015]~^ ERROR `&` without an explicit lifetime name cannot be used here
+//[rust2018]~^^ ERROR `&` without an explicit lifetime name cannot be used here
 { }
 
 fn main() {}

src/test/ui/underscore-lifetime/where-clause-trait-impl-underscore.rs

@@ -9,8 +9,8 @@ trait Foo { }
 impl<T> Foo for Vec<T>
 where
     T: WithRegion<'_>
-//[rust2015]~^ ERROR
-//[rust2018]~^^ ERROR
+//[rust2015]~^ ERROR `'_` cannot be used here
+//[rust2018]~^^ ERROR `'_` cannot be used here
 { }
 
 fn main() {}