Update error messages in various compile-fail tests

src/test/compile-fail/issue-15965.rs

@@ -12,8 +12,6 @@ fn main() {
     return
         { return () }
 //~^ ERROR the type of this value must be known in this context
-//~| ERROR this function takes 1 parameter
-//~| ERROR mismatched types
     ()
     ;
 }

src/test/compile-fail/issue-18345.rs

@@ -15,7 +15,6 @@ fn mapping<'f, R, T, U>(f: |T|: 'f -> U) -> &'f Transducer<'f, R, T, U> {
     |step| |r, x|
         step(r, f(x))
         //~^ ERROR the type of this value must be known in this context
-        //~| ERROR this function takes 1 parameter but 2 parameters were supplied
 }
 
 fn main() {}

src/test/compile-fail/issue-18532.rs

@@ -17,5 +17,4 @@
 fn main() {
     (return)((),());
     //~^ ERROR the type of this value must be known
-    //~| ERROR this function takes 1 parameter
 }

src/test/compile-fail/issue-18611.rs

@@ -10,10 +10,9 @@
 
 #![feature(associated_types)]
 
-fn add_state(op:
-    <int as HasState>::State
-//~^ ERROR it is currently unsupported to access associated types except through a type parameter
-) {}
+fn add_state(op: <int as HasState>::State) {
+//~^ ERROR the trait `HasState` is not implemented for the type `int`
+}
 
 trait HasState {
     type State;

src/test/compile-fail/issue-19081.rs

@@ -10,7 +10,7 @@
 
 #![feature(associated_types)]
 
-pub trait Hasher{
+pub trait Hasher {
     type State;
 
     fn hash<T: Hash<
@@ -18,7 +18,7 @@ pub trait Hasher{
     >>(&self, value: &T) -> u64;
 }
 
-trait Hash<S> {
+pub trait Hash<S> {
     fn hash(&self, state: &mut S);
 }
 

src/test/compile-fail/unsized4.rs

@@ -11,6 +11,7 @@
 // Test that bounds are sized-compatible.
 
 trait T {}
+
 fn f<Sized? Y: T>() {
 //~^ERROR incompatible bounds on type parameter `Y`, bound `T` does not allow unsized type
 }