Rollup merge of #74270 - davidtwco:issue-74086-more-placeholder-type-error, r=estebank

typeck: report placeholder type error w/out span

Fixes #74086.

This PR fixes a regression introduced in rust-lang/rust#70369 which meant that an error was not being emitted for invalid placeholder types when there wasn't a span available.

r? @estebank

6 files changed, 103 insertions, 63 deletions

diff --git a/src/librustc_typeck/astconv.rs b/src/librustc_typeck/astconv.rs
index 5d1949626dd..7581940b6ac 100644
--- a/src/librustc_typeck/astconv.rs
+++ b/src/librustc_typeck/astconv.rs
@@ -3049,14 +3049,14 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         let bare_fn_ty =
             ty::Binder::bind(tcx.mk_fn_sig(input_tys, output_ty, decl.c_variadic, unsafety, abi));
 
-        if let (false, Some(ident_span)) = (self.allow_ty_infer(), ident_span) {
+        if !self.allow_ty_infer() {
             // We always collect the spans for placeholder types when evaluating `fn`s, but we
             // only want to emit an error complaining about them if infer types (`_`) are not
             // allowed. `allow_ty_infer` gates this behavior. We check for the presence of
             // `ident_span` to not emit an error twice when we have `fn foo(_: fn() -> _)`.
             crate::collect::placeholder_type_error(
                 tcx,
-                ident_span.shrink_to_hi(),
+                ident_span.map(|sp| sp.shrink_to_hi()),
                 &generics.params[..],
                 visitor.0,
                 true,
diff --git a/src/librustc_typeck/collect.rs b/src/librustc_typeck/collect.rs
index 15481660a52..625b72091a6 100644
--- a/src/librustc_typeck/collect.rs
+++ b/src/librustc_typeck/collect.rs
@@ -129,7 +129,7 @@ struct CollectItemTypesVisitor<'tcx> {
 /// all already existing generic type parameters to avoid suggesting a name that is already in use.
 crate fn placeholder_type_error(
     tcx: TyCtxt<'tcx>,
-    span: Span,
+    span: Option<Span>,
     generics: &[hir::GenericParam<'_>],
     placeholder_types: Vec<Span>,
     suggest: bool,
@@ -137,12 +137,15 @@ crate fn placeholder_type_error(
     if placeholder_types.is_empty() {
         return;
     }
-    let type_name = generics.next_type_param_name(None);
 
+    let type_name = generics.next_type_param_name(None);
     let mut sugg: Vec<_> =
         placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
+
     if generics.is_empty() {
-        sugg.push((span, format!("<{}>", type_name)));
+        if let Some(span) = span {
+            sugg.push((span, format!("<{}>", type_name)));
+        }
     } else if let Some(arg) = generics.iter().find(|arg| match arg.name {
         hir::ParamName::Plain(Ident { name: kw::Underscore, .. }) => true,
         _ => false,
@@ -158,6 +161,7 @@ crate fn placeholder_type_error(
             format!(", {}", type_name),
         ));
     }
+
     let mut err = bad_placeholder_type(tcx, placeholder_types);
     if suggest {
         err.multipart_suggestion(
@@ -186,7 +190,7 @@ fn reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir
     let mut visitor = PlaceholderHirTyCollector::default();
     visitor.visit_item(item);
 
-    placeholder_type_error(tcx, generics.span, &generics.params[..], visitor.0, suggest);
+    placeholder_type_error(tcx, Some(generics.span), &generics.params[..], visitor.0, suggest);
 }
 
 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
@@ -722,7 +726,7 @@ fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::HirId) {
             // Account for `const C: _;` and `type T = _;`.
             let mut visitor = PlaceholderHirTyCollector::default();
             visitor.visit_trait_item(trait_item);
-            placeholder_type_error(tcx, DUMMY_SP, &[], visitor.0, false);
+            placeholder_type_error(tcx, None, &[], visitor.0, false);
         }
 
         hir::TraitItemKind::Type(_, None) => {}
@@ -745,7 +749,7 @@ fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::HirId) {
             // Account for `type T = _;`
             let mut visitor = PlaceholderHirTyCollector::default();
             visitor.visit_impl_item(impl_item);
-            placeholder_type_error(tcx, DUMMY_SP, &[], visitor.0, false);
+            placeholder_type_error(tcx, None, &[], visitor.0, false);
         }
         hir::ImplItemKind::Const(..) => {}
     }
diff --git a/src/test/ui/issues/issue-74086.rs b/src/test/ui/issues/issue-74086.rs
new file mode 100644
index 00000000000..f68a665b2f3
--- /dev/null
+++ b/src/test/ui/issues/issue-74086.rs
@@ -0,0 +1,4 @@
+fn main() {
+    static BUG: fn(_) -> u8 = |_| 8;
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures [E0121]
+}
diff --git a/src/test/ui/issues/issue-74086.stderr b/src/test/ui/issues/issue-74086.stderr
new file mode 100644
index 00000000000..4127f48a093
--- /dev/null
+++ b/src/test/ui/issues/issue-74086.stderr
@@ -0,0 +1,12 @@
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/issue-74086.rs:2:20
+   |
+LL |     static BUG: fn(_) -> u8 = |_| 8;
+   |                    ^
+   |                    |
+   |                    not allowed in type signatures
+   |                    help: use type parameters instead: `T`
+
+error: aborting due to previous error
+
+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 99a70230892..133c5231031 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item.rs
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.rs
@@ -32,6 +32,7 @@ fn test7(x: _) { let _x: usize = x; }
 
 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
 
 struct Test9;
 
@@ -98,6 +99,7 @@ pub fn main() {
 
     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
 
     struct FnTest9;
 
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.stderr b/src/test/ui/typeck/typeck_type_placeholder_item.stderr
index 6c0653d5fcb..a1945f2b9cf 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:152:18
+  --> $DIR/typeck_type_placeholder_item.rs:154:18
    |
 LL | struct BadStruct<_>(_);
    |                  ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:155:16
+  --> $DIR/typeck_type_placeholder_item.rs:157:16
    |
 LL | trait BadTrait<_> {}
    |                ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:165:19
+  --> $DIR/typeck_type_placeholder_item.rs:167:19
    |
 LL | struct BadStruct1<_, _>(_);
    |                   ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:165:22
+  --> $DIR/typeck_type_placeholder_item.rs:167:22
    |
 LL | struct BadStruct1<_, _>(_);
    |                      ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:170:19
+  --> $DIR/typeck_type_placeholder_item.rs:172:19
    |
 LL | struct BadStruct2<_, T>(_, T);
    |                   ^ expected identifier, found reserved identifier
 
 error: associated constant in `impl` without body
-  --> $DIR/typeck_type_placeholder_item.rs:201:5
+  --> $DIR/typeck_type_placeholder_item.rs:203:5
    |
 LL |     const C: _;
    |     ^^^^^^^^^^-
@@ -37,7 +37,7 @@ LL |     const C: _;
    |               help: provide a definition for the constant: `= <expr>;`
 
 error[E0403]: the name `_` is already used for a generic parameter in this item's generic parameters
-  --> $DIR/typeck_type_placeholder_item.rs:165:22
+  --> $DIR/typeck_type_placeholder_item.rs:167:22
    |
 LL | struct BadStruct1<_, _>(_);
    |                   -  ^ already used
@@ -135,6 +135,15 @@ error[E0121]: the type placeholder `_` is not allowed within types on item signa
   --> $DIR/typeck_type_placeholder_item.rs:33:22
    |
 LL | fn test8(_f: fn() -> _) { }
+   |                      ^
+   |                      |
+   |                      not allowed in type signatures
+   |                      help: use type parameters instead: `T`
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:33:22
+   |
+LL | fn test8(_f: fn() -> _) { }
    |                      ^ not allowed in type signatures
    |
 help: use type parameters instead
@@ -143,7 +152,7 @@ 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:47:26
    |
 LL | fn test11(x: &usize) -> &_ {
    |                         -^
@@ -152,7 +161,7 @@ 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:52:52
    |
 LL | unsafe fn test12(x: *const usize) -> *const *const _ {
    |                                      --------------^
@@ -161,7 +170,7 @@ 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:66:8
    |
 LL |     a: _,
    |        ^ not allowed in type signatures
@@ -180,13 +189,13 @@ LL |     b: (T, T),
    |
 
 error: missing type for `static` item
-  --> $DIR/typeck_type_placeholder_item.rs:71:12
+  --> $DIR/typeck_type_placeholder_item.rs:72:12
    |
 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:74:15
    |
 LL |     static B: _ = 42;
    |               ^
@@ -195,13 +204,13 @@ 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:76:15
    |
 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:79:21
    |
 LL |     fn fn_test() -> _ { 5 }
    |                     ^
@@ -210,7 +219,7 @@ 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:82:23
    |
 LL |     fn fn_test2() -> (_, _) { (5, 5) }
    |                      -^--^-
@@ -220,7 +229,7 @@ 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:85:22
    |
 LL |     static FN_TEST3: _ = "test";
    |                      ^
@@ -229,7 +238,7 @@ LL |     static FN_TEST3: _ = "test";
    |                      help: replace `_` with the correct type: `&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:88:22
    |
 LL |     static FN_TEST4: _ = 145;
    |                      ^
@@ -238,13 +247,13 @@ 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:91:22
    |
 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:94:20
    |
 LL |     fn fn_test6(_: _) { }
    |                    ^ not allowed in type signatures
@@ -255,7 +264,7 @@ 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:97:20
    |
 LL |     fn fn_test7(x: _) { let _x: usize = x; }
    |                    ^ not allowed in type signatures
@@ -266,7 +275,16 @@ 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:100:29
+   |
+LL |     fn fn_test8(_f: fn() -> _) { }
+   |                             ^
+   |                             |
+   |                             not allowed in type signatures
+   |                             help: use type parameters instead: `T`
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item.rs:100:29
    |
 LL |     fn fn_test8(_f: fn() -> _) { }
    |                             ^ not allowed in type signatures
@@ -277,7 +295,7 @@ 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:121:12
+  --> $DIR/typeck_type_placeholder_item.rs:123:12
    |
 LL |         a: _,
    |            ^ not allowed in type signatures
@@ -296,13 +314,13 @@ LL |         b: (T, T),
    |
 
 error[E0282]: type annotations needed
-  --> $DIR/typeck_type_placeholder_item.rs:126:18
+  --> $DIR/typeck_type_placeholder_item.rs:128:18
    |
 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:126:28
+  --> $DIR/typeck_type_placeholder_item.rs:128:28
    |
 LL |     fn fn_test11(_: _) -> (_, _) { panic!() }
    |                            ^  ^ not allowed in type signatures
@@ -310,7 +328,7 @@ 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:130:30
+  --> $DIR/typeck_type_placeholder_item.rs:132:30
    |
 LL |     fn fn_test12(x: i32) -> (_, _) { (x, x) }
    |                             -^--^-
@@ -320,7 +338,7 @@ 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:133:33
+  --> $DIR/typeck_type_placeholder_item.rs:135:33
    |
 LL |     fn fn_test13(x: _) -> (i32, _) { (x, x) }
    |                           ------^-
@@ -329,7 +347,7 @@ 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:152:21
+  --> $DIR/typeck_type_placeholder_item.rs:154:21
    |
 LL | struct BadStruct<_>(_);
    |                     ^ not allowed in type signatures
@@ -340,7 +358,7 @@ LL | struct BadStruct<T>(T);
    |                  ^  ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:157:15
+  --> $DIR/typeck_type_placeholder_item.rs:159:15
    |
 LL | impl BadTrait<_> for BadStruct<_> {}
    |               ^                ^ not allowed in type signatures
@@ -353,13 +371,13 @@ 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:160:34
+  --> $DIR/typeck_type_placeholder_item.rs:162:34
    |
 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:165:25
+  --> $DIR/typeck_type_placeholder_item.rs:167:25
    |
 LL | struct BadStruct1<_, _>(_);
    |                         ^ not allowed in type signatures
@@ -370,7 +388,7 @@ LL | struct BadStruct1<T, _>(T);
    |                   ^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:170:25
+  --> $DIR/typeck_type_placeholder_item.rs:172:25
    |
 LL | struct BadStruct2<_, T>(_, T);
    |                         ^ not allowed in type signatures
@@ -381,13 +399,13 @@ LL | struct BadStruct2<U, T>(U, T);
    |                   ^     ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:174:14
+  --> $DIR/typeck_type_placeholder_item.rs:176:14
    |
 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:43:27
    |
 LL |     fn test10(&self, _x : _) { }
    |                           ^ not allowed in type signatures
@@ -398,7 +416,7 @@ 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:138:31
+  --> $DIR/typeck_type_placeholder_item.rs:140:31
    |
 LL |     fn method_test1(&self, x: _);
    |                               ^ not allowed in type signatures
@@ -409,7 +427,7 @@ 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:140:31
+  --> $DIR/typeck_type_placeholder_item.rs:142:31
    |
 LL |     fn method_test2(&self, x: _) -> _;
    |                               ^     ^ not allowed in type signatures
@@ -422,7 +440,7 @@ 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:142:31
+  --> $DIR/typeck_type_placeholder_item.rs:144:31
    |
 LL |     fn method_test3(&self) -> _;
    |                               ^ not allowed in type signatures
@@ -433,7 +451,7 @@ 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:144:26
+  --> $DIR/typeck_type_placeholder_item.rs:146:26
    |
 LL |     fn assoc_fn_test1(x: _);
    |                          ^ not allowed in type signatures
@@ -444,7 +462,7 @@ 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:146:26
+  --> $DIR/typeck_type_placeholder_item.rs:148:26
    |
 LL |     fn assoc_fn_test2(x: _) -> _;
    |                          ^     ^ not allowed in type signatures
@@ -457,7 +475,7 @@ 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:148:28
+  --> $DIR/typeck_type_placeholder_item.rs:150:28
    |
 LL |     fn assoc_fn_test3() -> _;
    |                            ^ not allowed in type signatures
@@ -468,7 +486,7 @@ 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:61:37
    |
 LL |     fn clone_from(&mut self, other: _) { *self = Test9; }
    |                                     ^ not allowed in type signatures
@@ -479,7 +497,7 @@ 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:108:34
+  --> $DIR/typeck_type_placeholder_item.rs:110:34
    |
 LL |         fn fn_test10(&self, _x : _) { }
    |                                  ^ not allowed in type signatures
@@ -490,7 +508,7 @@ 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:116:41
+  --> $DIR/typeck_type_placeholder_item.rs:118:41
    |
 LL |         fn clone_from(&mut self, other: _) { *self = FnTest9; }
    |                                         ^ not allowed in type signatures
@@ -501,25 +519,25 @@ 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:180:21
+  --> $DIR/typeck_type_placeholder_item.rs:182:21
    |
 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:188:14
+  --> $DIR/typeck_type_placeholder_item.rs:190:14
    |
 LL |     type 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:190:14
+  --> $DIR/typeck_type_placeholder_item.rs:192:14
    |
 LL |     const C: _;
    |              ^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:192:14
+  --> $DIR/typeck_type_placeholder_item.rs:194:14
    |
 LL |     const D: _ = 42;
    |              ^
@@ -528,7 +546,7 @@ LL |     const D: _ = 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:39:24
+  --> $DIR/typeck_type_placeholder_item.rs:40:24
    |
 LL |     fn test9(&self) -> _ { () }
    |                        ^
@@ -537,7 +555,7 @@ 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:58:24
    |
 LL |     fn clone(&self) -> _ { Test9 }
    |                        ^
@@ -546,7 +564,7 @@ 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:105:31
+  --> $DIR/typeck_type_placeholder_item.rs:107:31
    |
 LL |         fn fn_test9(&self) -> _ { () }
    |                               ^
@@ -555,7 +573,7 @@ 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:113:28
+  --> $DIR/typeck_type_placeholder_item.rs:115:28
    |
 LL |         fn clone(&self) -> _ { FnTest9 }
    |                            ^
@@ -564,25 +582,25 @@ LL |         fn clone(&self) -> _ { FnTest9 }
    |                            help: replace with the correct return type: `main::FnTest9`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:197:14
+  --> $DIR/typeck_type_placeholder_item.rs:199:14
    |
 LL |     type 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:199:14
+  --> $DIR/typeck_type_placeholder_item.rs:201:14
    |
 LL |     type 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:201:14
+  --> $DIR/typeck_type_placeholder_item.rs:203:14
    |
 LL |     const C: _;
    |              ^ not allowed in type signatures
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:204:14
+  --> $DIR/typeck_type_placeholder_item.rs:206:14
    |
 LL |     const D: _ = 42;
    |              ^
@@ -590,7 +608,7 @@ LL |     const D: _ = 42;
    |              not allowed in type signatures
    |              help: replace `_` with the correct type: `i32`
 
-error: aborting due to 64 previous errors
+error: aborting due to 66 previous errors
 
 Some errors have detailed explanations: E0121, E0282, E0403.
 For more information about an error, try `rustc --explain E0121`.