Three random test cases that seem to produce more errors now. I've

not dug deeply into what is going on here, although the errors ARE
somewhat surprising.

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

@@ -10,7 +10,10 @@
 
 fn main() {
     return
-        { return () } //~ ERROR the type of this value must be known in this context
+        { 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

@@ -13,7 +13,9 @@ type Transducer<'t, R, T, U> = |Step<'t, R, U>|: 't -> Step<'t, R, T>;
 
 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
+        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

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