diff --git a/src/librustc_typeck/collect.rs b/src/librustc_typeck/collect.rs
index 80d914d8d0ae5..79dc181749894 100644
--- a/src/librustc_typeck/collect.rs
+++ b/src/librustc_typeck/collect.rs
@@ -319,7 +319,7 @@ impl AstConv<'tcx> for ItemCtxt<'tcx> {
     }
 
     fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
-        self.tcx().sess.delay_span_bug(span, "bad placeholder type");
+        placeholder_type_error(self.tcx(), span, &[], vec![span], false);
         self.tcx().types.err
     }
 
diff --git a/src/test/ui/did_you_mean/bad-assoc-ty.rs b/src/test/ui/did_you_mean/bad-assoc-ty.rs
index fccfb7911cecf..f02931eeb6fc3 100644
--- a/src/test/ui/did_you_mean/bad-assoc-ty.rs
+++ b/src/test/ui/did_you_mean/bad-assoc-ty.rs
@@ -17,6 +17,7 @@ type D = (u8, u8)::AssocTy;
 type E = _::AssocTy;
 //~^ ERROR missing angle brackets in associated item path
 //~| ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
 type F = &'static (u8)::AssocTy;
 //~^ ERROR missing angle brackets in associated item path
diff --git a/src/test/ui/did_you_mean/bad-assoc-ty.stderr b/src/test/ui/did_you_mean/bad-assoc-ty.stderr
index 64e49934d8762..d5b2abf2f8b50 100644
--- a/src/test/ui/did_you_mean/bad-assoc-ty.stderr
+++ b/src/test/ui/did_you_mean/bad-assoc-ty.stderr
@@ -29,25 +29,25 @@ LL | type E = _::AssocTy;
    |          ^^^^^^^^^^ help: try: `<_>::AssocTy`
 
 error: missing angle brackets in associated item path
-  --> $DIR/bad-assoc-ty.rs:21:19
+  --> $DIR/bad-assoc-ty.rs:22:19
    |
 LL | type F = &'static (u8)::AssocTy;
    |                   ^^^^^^^^^^^^^ help: try: `<(u8)>::AssocTy`
 
 error: missing angle brackets in associated item path
-  --> $DIR/bad-assoc-ty.rs:27:10
+  --> $DIR/bad-assoc-ty.rs:28:10
    |
 LL | type G = dyn 'static + (Send)::AssocTy;
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `<dyn 'static + (Send)>::AssocTy`
 
 error: missing angle brackets in associated item path
-  --> $DIR/bad-assoc-ty.rs:44:10
+  --> $DIR/bad-assoc-ty.rs:45:10
    |
 LL | type I = ty!()::AssocTy;
    |          ^^^^^^^^^^^^^^ help: try: `<ty!()>::AssocTy`
 
 error: missing angle brackets in associated item path
-  --> $DIR/bad-assoc-ty.rs:37:19
+  --> $DIR/bad-assoc-ty.rs:38:19
    |
 LL |     ($ty: ty) => ($ty::AssocTy);
    |                   ^^^^^^^^^^^^ help: try: `<$ty>::AssocTy`
@@ -87,26 +87,32 @@ error[E0121]: the type placeholder `_` is not allowed within types on item signa
 LL | type E = _::AssocTy;
    |          ^ not allowed in type signatures
 
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/bad-assoc-ty.rs:17:10
+   |
+LL | type E = _::AssocTy;
+   |          ^ not allowed in type signatures
+
 error[E0223]: ambiguous associated type
-  --> $DIR/bad-assoc-ty.rs:21:19
+  --> $DIR/bad-assoc-ty.rs:22:19
    |
 LL | type F = &'static (u8)::AssocTy;
    |                   ^^^^^^^^^^^^^ help: use fully-qualified syntax: `<u8 as Trait>::AssocTy`
 
 error[E0223]: ambiguous associated type
-  --> $DIR/bad-assoc-ty.rs:27:10
+  --> $DIR/bad-assoc-ty.rs:28:10
    |
 LL | type G = dyn 'static + (Send)::AssocTy;
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<(dyn std::marker::Send + 'static) as Trait>::AssocTy`
 
 error[E0223]: ambiguous associated type
-  --> $DIR/bad-assoc-ty.rs:33:10
+  --> $DIR/bad-assoc-ty.rs:34:10
    |
 LL | type H = Fn(u8) -> (u8)::Output;
    |          ^^^^^^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<(dyn std::ops::Fn(u8) -> u8 + 'static) as Trait>::Output`
 
 error[E0223]: ambiguous associated type
-  --> $DIR/bad-assoc-ty.rs:37:19
+  --> $DIR/bad-assoc-ty.rs:38:19
    |
 LL |     ($ty: ty) => ($ty::AssocTy);
    |                   ^^^^^^^^^^^^ help: use fully-qualified syntax: `<u8 as Trait>::AssocTy`
@@ -117,12 +123,12 @@ LL | type J = ty!(u8);
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0223]: ambiguous associated type
-  --> $DIR/bad-assoc-ty.rs:44:10
+  --> $DIR/bad-assoc-ty.rs:45:10
    |
 LL | type I = ty!()::AssocTy;
    |          ^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<u8 as Trait>::AssocTy`
 
-error: aborting due to 19 previous errors
+error: aborting due to 20 previous errors
 
 Some errors have detailed explanations: E0121, E0223.
 For more information about an error, try `rustc --explain E0121`.
diff --git a/src/test/ui/self/self-infer.rs b/src/test/ui/self/self-infer.rs
index 0956f2a56918c..77c80521236a0 100644
--- a/src/test/ui/self/self-infer.rs
+++ b/src/test/ui/self/self-infer.rs
@@ -2,7 +2,9 @@ struct S;
 
 impl S {
     fn f(self: _) {} //~ERROR the type placeholder `_` is not allowed within types on item sig
+    //~^ ERROR the type placeholder `_` is not allowed within types on item sig
     fn g(self: &_) {} //~ERROR the type placeholder `_` is not allowed within types on item sig
+    //~^ ERROR the type placeholder `_` is not allowed within types on item sig
 }
 
 fn main() {}
diff --git a/src/test/ui/self/self-infer.stderr b/src/test/ui/self/self-infer.stderr
index 1475b212b56a6..d6bf8b44d6099 100644
--- a/src/test/ui/self/self-infer.stderr
+++ b/src/test/ui/self/self-infer.stderr
@@ -1,3 +1,9 @@
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/self-infer.rs:4:16
+   |
+LL |     fn f(self: _) {}
+   |                ^ not allowed in type signatures
+
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
   --> $DIR/self-infer.rs:4:16
    |
@@ -10,7 +16,13 @@ LL |     fn f<T>(self: T) {}
    |         ^^^       ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/self-infer.rs:5:17
+  --> $DIR/self-infer.rs:6:17
+   |
+LL |     fn g(self: &_) {}
+   |                 ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/self-infer.rs:6:17
    |
 LL |     fn g(self: &_) {}
    |                 ^ not allowed in type signatures
@@ -20,6 +32,6 @@ help: use type parameters instead
 LL |     fn g<T>(self: &T) {}
    |         ^^^        ^
 
-error: aborting due to 2 previous errors
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.rs b/src/test/ui/typeck/typeck_type_placeholder_item.rs
index 86c7c52b27166..eb6cc832fb417 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item.rs
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.rs
@@ -19,19 +19,24 @@ static TEST5: (_, _) = (1, 2);
 
 fn test6(_: _) { }
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
 fn test6_b<T>(_: _, _: T) { }
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
 fn test6_c<T, K, L, A, B>(_: _, _: (T, K, L, A, B)) { }
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
 fn test7(x: _) { let _x: usize = x; }
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
 fn test8(_f: fn() -> _) { }
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
 //~| ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
 struct Test9;
 
@@ -41,6 +46,7 @@ impl Test9 {
 
     fn test10(&self, _x : _) { }
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
 }
 
 fn test11(x: &usize) -> &_ {
@@ -59,12 +65,16 @@ impl Clone for Test9 {
 
     fn clone_from(&mut self, other: _) { *self = Test9; }
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
 }
 
 struct Test10 {
     a: _,
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
     b: (_, _),
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
 }
 
 pub fn main() {
@@ -92,13 +102,16 @@ pub fn main() {
 
     fn fn_test6(_: _) { }
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
     fn fn_test7(x: _) { let _x: usize = x; }
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
     fn fn_test8(_f: fn() -> _) { }
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
     //~| ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
     struct FnTest9;
 
@@ -108,6 +121,7 @@ pub fn main() {
 
         fn fn_test10(&self, _x : _) { }
         //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+        //~| ERROR the type placeholder `_` is not allowed within types on item signatures
     }
 
     impl Clone for FnTest9 {
@@ -116,12 +130,16 @@ pub fn main() {
 
         fn clone_from(&mut self, other: _) { *self = FnTest9; }
         //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+        //~| ERROR the type placeholder `_` is not allowed within types on item signatures
     }
 
     struct FnTest10 {
         a: _,
         //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+        //~| ERROR the type placeholder `_` is not allowed within types on item signatures
         b: (_, _),
+        //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+        //~| ERROR the type placeholder `_` is not allowed within types on item signatures
     }
 
     fn fn_test11(_: _) -> (_, _) { panic!() }
@@ -138,28 +156,40 @@ pub fn main() {
 trait T {
     fn method_test1(&self, x: _);
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
     fn method_test2(&self, x: _) -> _;
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
     fn method_test3(&self) -> _;
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
     fn assoc_fn_test1(x: _);
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
     fn assoc_fn_test2(x: _) -> _;
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
     fn assoc_fn_test3() -> _;
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
 }
 
 struct BadStruct<_>(_);
 //~^ ERROR expected identifier, found reserved identifier `_`
 //~| ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 trait BadTrait<_> {}
 //~^ ERROR expected identifier, found reserved identifier `_`
 impl BadTrait<_> for BadStruct<_> {}
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
 fn impl_trait() -> impl BadTrait<_> {
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
     unimplemented!()
 }
 
@@ -168,18 +198,22 @@ struct BadStruct1<_, _>(_);
 //~| ERROR expected identifier, found reserved identifier `_`
 //~| ERROR the name `_` is already used
 //~| ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 struct BadStruct2<_, T>(_, T);
 //~^ ERROR expected identifier, found reserved identifier `_`
 //~| ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
 type X = Box<_>;
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
 struct Struct;
 trait Trait<T> {}
 impl Trait<usize> for Struct {}
 type Y = impl Trait<_>;
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 fn foo() -> Y {
     Struct
 }
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.stderr b/src/test/ui/typeck/typeck_type_placeholder_item.stderr
index 95e8f94c6f3e7..a8fdd66ee3753 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item.stderr
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.stderr
@@ -1,35 +1,35 @@
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:153:18
+  --> $DIR/typeck_type_placeholder_item.rs:179:18
    |
 LL | struct BadStruct<_>(_);
    |                  ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:156:16
+  --> $DIR/typeck_type_placeholder_item.rs:183:16
    |
 LL | trait BadTrait<_> {}
    |                ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:166:19
+  --> $DIR/typeck_type_placeholder_item.rs:196:19
    |
 LL | struct BadStruct1<_, _>(_);
    |                   ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:166:22
+  --> $DIR/typeck_type_placeholder_item.rs:196:22
    |
 LL | struct BadStruct1<_, _>(_);
    |                      ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:171:19
+  --> $DIR/typeck_type_placeholder_item.rs:202:19
    |
 LL | struct BadStruct2<_, T>(_, T);
    |                   ^ expected identifier, found reserved identifier
 
 error[E0403]: the name `_` is already used for a generic parameter in this item's generic parameters
-  --> $DIR/typeck_type_placeholder_item.rs:166:22
+  --> $DIR/typeck_type_placeholder_item.rs:196:22
    |
 LL | struct BadStruct1<_, _>(_);
    |                   -  ^ already used
@@ -79,6 +79,12 @@ error[E0121]: the type placeholder `_` is not allowed within types on item signa
 LL | static TEST5: (_, _) = (1, 2);
    |               ^^^^^^ not allowed in type signatures
 
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:20:13
+   |
+LL | fn test6(_: _) { }
+   |             ^ not allowed in type signatures
+
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
   --> $DIR/typeck_type_placeholder_item.rs:20:13
    |
@@ -91,7 +97,13 @@ LL | fn test6<T>(_: T) { }
    |         ^^^    ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:23:18
+  --> $DIR/typeck_type_placeholder_item.rs:24:18
+   |
+LL | fn test6_b<T>(_: _, _: T) { }
+   |                  ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:24:18
    |
 LL | fn test6_b<T>(_: _, _: T) { }
    |                  ^ not allowed in type signatures
@@ -102,7 +114,13 @@ LL | fn test6_b<T, K>(_: K, _: T) { }
    |             ^^^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:26:30
+  --> $DIR/typeck_type_placeholder_item.rs:28:30
+   |
+LL | fn test6_c<T, K, L, A, B>(_: _, _: (T, K, L, A, B)) { }
+   |                              ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:28:30
    |
 LL | fn test6_c<T, K, L, A, B>(_: _, _: (T, K, L, A, B)) { }
    |                              ^ not allowed in type signatures
@@ -113,7 +131,13 @@ LL | fn test6_c<T, K, L, A, B, C>(_: C, _: (T, K, L, A, B)) { }
    |                         ^^^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:29:13
+  --> $DIR/typeck_type_placeholder_item.rs:32:13
+   |
+LL | fn test7(x: _) { let _x: usize = x; }
+   |             ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:32:13
    |
 LL | fn test7(x: _) { let _x: usize = x; }
    |             ^ not allowed in type signatures
@@ -124,13 +148,19 @@ LL | fn test7<T>(x: T) { let _x: usize = x; }
    |         ^^^    ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:32:22
+  --> $DIR/typeck_type_placeholder_item.rs:36:22
    |
 LL | fn test8(_f: fn() -> _) { }
    |                      ^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:32:22
+  --> $DIR/typeck_type_placeholder_item.rs:36:22
+   |
+LL | fn test8(_f: fn() -> _) { }
+   |                      ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:36:22
    |
 LL | fn test8(_f: fn() -> _) { }
    |                      ^ not allowed in type signatures
@@ -141,7 +171,61 @@ LL | fn test8<T>(_f: fn() -> T) { }
    |         ^^^             ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:46:26
+  --> $DIR/typeck_type_placeholder_item.rs:72:8
+   |
+LL |     a: _,
+   |        ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:75:9
+   |
+LL |     b: (_, _),
+   |         ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:75:12
+   |
+LL |     b: (_, _),
+   |            ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:137:12
+   |
+LL |         a: _,
+   |            ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:140:13
+   |
+LL |         b: (_, _),
+   |             ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:140:16
+   |
+LL |         b: (_, _),
+   |                ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:179:21
+   |
+LL | struct BadStruct<_>(_);
+   |                     ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:196:25
+   |
+LL | struct BadStruct1<_, _>(_);
+   |                         ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:202:25
+   |
+LL | struct BadStruct2<_, T>(_, T);
+   |                         ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:52:26
    |
 LL | fn test11(x: &usize) -> &_ {
    |                         -^
@@ -150,7 +234,7 @@ LL | fn test11(x: &usize) -> &_ {
    |                         help: replace with the correct return type: `&&usize`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:51:52
+  --> $DIR/typeck_type_placeholder_item.rs:57:52
    |
 LL | unsafe fn test12(x: *const usize) -> *const *const _ {
    |                                      --------------^
@@ -159,11 +243,11 @@ LL | unsafe fn test12(x: *const usize) -> *const *const _ {
    |                                      help: replace with the correct return type: `*const *const usize`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:65:8
+  --> $DIR/typeck_type_placeholder_item.rs:72:8
    |
 LL |     a: _,
    |        ^ not allowed in type signatures
-LL |
+...
 LL |     b: (_, _),
    |         ^  ^ not allowed in type signatures
    |         |
@@ -174,17 +258,18 @@ help: use type parameters instead
 LL | struct Test10<T> {
 LL |     a: T,
 LL |
+LL |
 LL |     b: (T, T),
    |
 
 error: missing type for `static` item
-  --> $DIR/typeck_type_placeholder_item.rs:71:12
+  --> $DIR/typeck_type_placeholder_item.rs:81:12
    |
 LL |     static A = 42;
    |            ^ help: provide a type for the item: `A: i32`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:73:15
+  --> $DIR/typeck_type_placeholder_item.rs:83:15
    |
 LL |     static B: _ = 42;
    |               ^
@@ -193,13 +278,13 @@ LL |     static B: _ = 42;
    |               help: replace `_` with the correct type: `i32`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:75:15
+  --> $DIR/typeck_type_placeholder_item.rs:85:15
    |
 LL |     static C: Option<_> = Some(42);
    |               ^^^^^^^^^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:78:21
+  --> $DIR/typeck_type_placeholder_item.rs:88:21
    |
 LL |     fn fn_test() -> _ { 5 }
    |                     ^
@@ -208,7 +293,7 @@ LL |     fn fn_test() -> _ { 5 }
    |                     help: replace with the correct return type: `i32`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:81:23
+  --> $DIR/typeck_type_placeholder_item.rs:91:23
    |
 LL |     fn fn_test2() -> (_, _) { (5, 5) }
    |                      -^--^-
@@ -218,7 +303,7 @@ LL |     fn fn_test2() -> (_, _) { (5, 5) }
    |                      help: replace with the correct return type: `(i32, i32)`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:84:22
+  --> $DIR/typeck_type_placeholder_item.rs:94:22
    |
 LL |     static FN_TEST3: _ = "test";
    |                      ^
@@ -227,7 +312,7 @@ LL |     static FN_TEST3: _ = "test";
    |                      help: replace `_` with the correct type: `&'static str`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:87:22
+  --> $DIR/typeck_type_placeholder_item.rs:97:22
    |
 LL |     static FN_TEST4: _ = 145;
    |                      ^
@@ -236,13 +321,19 @@ LL |     static FN_TEST4: _ = 145;
    |                      help: replace `_` with the correct type: `i32`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:90:22
+  --> $DIR/typeck_type_placeholder_item.rs:100:22
    |
 LL |     static FN_TEST5: (_, _) = (1, 2);
    |                      ^^^^^^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:93:20
+  --> $DIR/typeck_type_placeholder_item.rs:103:20
+   |
+LL |     fn fn_test6(_: _) { }
+   |                    ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:103:20
    |
 LL |     fn fn_test6(_: _) { }
    |                    ^ not allowed in type signatures
@@ -253,7 +344,13 @@ LL |     fn fn_test6<T>(_: T) { }
    |                ^^^    ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:96:20
+  --> $DIR/typeck_type_placeholder_item.rs:107:20
+   |
+LL |     fn fn_test7(x: _) { let _x: usize = x; }
+   |                    ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:107:20
    |
 LL |     fn fn_test7(x: _) { let _x: usize = x; }
    |                    ^ not allowed in type signatures
@@ -264,13 +361,19 @@ LL |     fn fn_test7<T>(x: T) { let _x: usize = x; }
    |                ^^^    ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:99:29
+  --> $DIR/typeck_type_placeholder_item.rs:111:29
+   |
+LL |     fn fn_test8(_f: fn() -> _) { }
+   |                             ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:111:29
    |
 LL |     fn fn_test8(_f: fn() -> _) { }
    |                             ^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:99:29
+  --> $DIR/typeck_type_placeholder_item.rs:111:29
    |
 LL |     fn fn_test8(_f: fn() -> _) { }
    |                             ^ not allowed in type signatures
@@ -281,11 +384,11 @@ LL |     fn fn_test8<T>(_f: fn() -> T) { }
    |                ^^^             ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:122:12
+  --> $DIR/typeck_type_placeholder_item.rs:137:12
    |
 LL |         a: _,
    |            ^ not allowed in type signatures
-LL |
+...
 LL |         b: (_, _),
    |             ^  ^ not allowed in type signatures
    |             |
@@ -296,17 +399,18 @@ help: use type parameters instead
 LL |     struct FnTest10<T> {
 LL |         a: T,
 LL |
+LL |
 LL |         b: (T, T),
    |
 
 error[E0282]: type annotations needed
-  --> $DIR/typeck_type_placeholder_item.rs:127:18
+  --> $DIR/typeck_type_placeholder_item.rs:145:18
    |
 LL |     fn fn_test11(_: _) -> (_, _) { panic!() }
    |                  ^ cannot infer type
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:127:28
+  --> $DIR/typeck_type_placeholder_item.rs:145:28
    |
 LL |     fn fn_test11(_: _) -> (_, _) { panic!() }
    |                            ^  ^ not allowed in type signatures
@@ -314,7 +418,7 @@ LL |     fn fn_test11(_: _) -> (_, _) { panic!() }
    |                            not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:131:30
+  --> $DIR/typeck_type_placeholder_item.rs:149:30
    |
 LL |     fn fn_test12(x: i32) -> (_, _) { (x, x) }
    |                             -^--^-
@@ -324,7 +428,7 @@ LL |     fn fn_test12(x: i32) -> (_, _) { (x, x) }
    |                             help: replace with the correct return type: `(i32, i32)`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:134:33
+  --> $DIR/typeck_type_placeholder_item.rs:152:33
    |
 LL |     fn fn_test13(x: _) -> (i32, _) { (x, x) }
    |                           ------^-
@@ -333,7 +437,7 @@ LL |     fn fn_test13(x: _) -> (i32, _) { (x, x) }
    |                           help: replace with the correct return type: `(i32, i32)`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:153:21
+  --> $DIR/typeck_type_placeholder_item.rs:179:21
    |
 LL | struct BadStruct<_>(_);
    |                     ^ not allowed in type signatures
@@ -344,7 +448,19 @@ LL | struct BadStruct<T>(T);
    |                  ^  ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:158:15
+  --> $DIR/typeck_type_placeholder_item.rs:185:32
+   |
+LL | impl BadTrait<_> for BadStruct<_> {}
+   |                                ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:185:15
+   |
+LL | impl BadTrait<_> for BadStruct<_> {}
+   |               ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:185:15
    |
 LL | impl BadTrait<_> for BadStruct<_> {}
    |               ^                ^ not allowed in type signatures
@@ -357,13 +473,13 @@ LL | impl<T> BadTrait<T> for BadStruct<T> {}
    |     ^^^          ^                ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:161:34
+  --> $DIR/typeck_type_placeholder_item.rs:190:34
    |
 LL | fn impl_trait() -> impl BadTrait<_> {
    |                                  ^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:166:25
+  --> $DIR/typeck_type_placeholder_item.rs:196:25
    |
 LL | struct BadStruct1<_, _>(_);
    |                         ^ not allowed in type signatures
@@ -374,7 +490,7 @@ LL | struct BadStruct1<T, _>(T);
    |                   ^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:171:25
+  --> $DIR/typeck_type_placeholder_item.rs:202:25
    |
 LL | struct BadStruct2<_, T>(_, T);
    |                         ^ not allowed in type signatures
@@ -385,13 +501,25 @@ LL | struct BadStruct2<K, T>(K, T);
    |                   ^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:175:14
+  --> $DIR/typeck_type_placeholder_item.rs:207:14
    |
 LL | type X = Box<_>;
    |              ^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:42:27
+  --> $DIR/typeck_type_placeholder_item.rs:207:14
+   |
+LL | type X = Box<_>;
+   |              ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:47:27
+   |
+LL |     fn test10(&self, _x : _) { }
+   |                           ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:47:27
    |
 LL |     fn test10(&self, _x : _) { }
    |                           ^ not allowed in type signatures
@@ -402,7 +530,13 @@ LL |     fn test10<T>(&self, _x : T) { }
    |              ^^^             ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:139:31
+  --> $DIR/typeck_type_placeholder_item.rs:157:31
+   |
+LL |     fn method_test1(&self, x: _);
+   |                               ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:157:31
    |
 LL |     fn method_test1(&self, x: _);
    |                               ^ not allowed in type signatures
@@ -413,7 +547,19 @@ LL |     fn method_test1<T>(&self, x: T);
    |                    ^^^           ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:141:31
+  --> $DIR/typeck_type_placeholder_item.rs:160:37
+   |
+LL |     fn method_test2(&self, x: _) -> _;
+   |                                     ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:160:31
+   |
+LL |     fn method_test2(&self, x: _) -> _;
+   |                               ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:160:31
    |
 LL |     fn method_test2(&self, x: _) -> _;
    |                               ^     ^ not allowed in type signatures
@@ -426,7 +572,13 @@ LL |     fn method_test2<T>(&self, x: T) -> T;
    |                    ^^^           ^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:143:31
+  --> $DIR/typeck_type_placeholder_item.rs:164:31
+   |
+LL |     fn method_test3(&self) -> _;
+   |                               ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:164:31
    |
 LL |     fn method_test3(&self) -> _;
    |                               ^ not allowed in type signatures
@@ -437,7 +589,13 @@ LL |     fn method_test3<T>(&self) -> T;
    |                    ^^^           ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:145:26
+  --> $DIR/typeck_type_placeholder_item.rs:167:26
+   |
+LL |     fn assoc_fn_test1(x: _);
+   |                          ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:167:26
    |
 LL |     fn assoc_fn_test1(x: _);
    |                          ^ not allowed in type signatures
@@ -448,7 +606,19 @@ LL |     fn assoc_fn_test1<T>(x: T);
    |                      ^^^    ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:147:26
+  --> $DIR/typeck_type_placeholder_item.rs:170:32
+   |
+LL |     fn assoc_fn_test2(x: _) -> _;
+   |                                ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:170:26
+   |
+LL |     fn assoc_fn_test2(x: _) -> _;
+   |                          ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:170:26
    |
 LL |     fn assoc_fn_test2(x: _) -> _;
    |                          ^     ^ not allowed in type signatures
@@ -461,7 +631,13 @@ LL |     fn assoc_fn_test2<T>(x: T) -> T;
    |                      ^^^    ^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:149:28
+  --> $DIR/typeck_type_placeholder_item.rs:174:28
+   |
+LL |     fn assoc_fn_test3() -> _;
+   |                            ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:174:28
    |
 LL |     fn assoc_fn_test3() -> _;
    |                            ^ not allowed in type signatures
@@ -472,7 +648,13 @@ LL |     fn assoc_fn_test3<T>() -> T;
    |                      ^^^      ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:60:37
+  --> $DIR/typeck_type_placeholder_item.rs:66:37
+   |
+LL |     fn clone_from(&mut self, other: _) { *self = Test9; }
+   |                                     ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:66:37
    |
 LL |     fn clone_from(&mut self, other: _) { *self = Test9; }
    |                                     ^ not allowed in type signatures
@@ -483,7 +665,13 @@ LL |     fn clone_from<T>(&mut self, other: T) { *self = Test9; }
    |                  ^^^                   ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:109:34
+  --> $DIR/typeck_type_placeholder_item.rs:122:34
+   |
+LL |         fn fn_test10(&self, _x : _) { }
+   |                                  ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:122:34
    |
 LL |         fn fn_test10(&self, _x : _) { }
    |                                  ^ not allowed in type signatures
@@ -494,7 +682,13 @@ LL |         fn fn_test10<T>(&self, _x : T) { }
    |                     ^^^             ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:117:41
+  --> $DIR/typeck_type_placeholder_item.rs:131:41
+   |
+LL |         fn clone_from(&mut self, other: _) { *self = FnTest9; }
+   |                                         ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:131:41
    |
 LL |         fn clone_from(&mut self, other: _) { *self = FnTest9; }
    |                                         ^ not allowed in type signatures
@@ -505,13 +699,25 @@ LL |         fn clone_from<T>(&mut self, other: T) { *self = FnTest9; }
    |                      ^^^                   ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:181:21
+  --> $DIR/typeck_type_placeholder_item.rs:190:34
+   |
+LL | fn impl_trait() -> impl BadTrait<_> {
+   |                                  ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:214:21
+   |
+LL | type Y = impl Trait<_>;
+   |                     ^ not allowed in type signatures
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:214:21
    |
 LL | type Y = impl Trait<_>;
    |                     ^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:39:24
+  --> $DIR/typeck_type_placeholder_item.rs:44:24
    |
 LL |     fn test9(&self) -> _ { () }
    |                        ^
@@ -520,7 +726,7 @@ LL |     fn test9(&self) -> _ { () }
    |                        help: replace with the correct return type: `()`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:57:24
+  --> $DIR/typeck_type_placeholder_item.rs:63:24
    |
 LL |     fn clone(&self) -> _ { Test9 }
    |                        ^
@@ -529,7 +735,7 @@ LL |     fn clone(&self) -> _ { Test9 }
    |                        help: replace with the correct return type: `Test9`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:106:31
+  --> $DIR/typeck_type_placeholder_item.rs:119:31
    |
 LL |         fn fn_test9(&self) -> _ { () }
    |                               ^
@@ -538,7 +744,7 @@ LL |         fn fn_test9(&self) -> _ { () }
    |                               help: replace with the correct return type: `()`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:114:28
+  --> $DIR/typeck_type_placeholder_item.rs:128:28
    |
 LL |         fn clone(&self) -> _ { FnTest9 }
    |                            ^
@@ -546,7 +752,7 @@ LL |         fn clone(&self) -> _ { FnTest9 }
    |                            not allowed in type signatures
    |                            help: replace with the correct return type: `main::FnTest9`
 
-error: aborting due to 58 previous errors
+error: aborting due to 92 previous errors
 
 Some errors have detailed explanations: E0121, E0282, E0403.
 For more information about an error, try `rustc --explain E0121`.