Rollup merge of #86223 - fee1-dead:better-E0121, r=petrochenkov

Specify the kind of the item for E0121

Fixes #86005

34 files changed, 455 insertions, 388 deletions

diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index bb8d6386d8a..a7ce92ea579 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -2815,6 +2815,27 @@ impl ItemKind<'_> {
             _ => return None,
         })
     }
+
+    pub fn descr(&self) -> &'static str {
+        match self {
+            ItemKind::ExternCrate(..) => "extern crate",
+            ItemKind::Use(..) => "`use` import",
+            ItemKind::Static(..) => "static item",
+            ItemKind::Const(..) => "constant item",
+            ItemKind::Fn(..) => "function",
+            ItemKind::Mod(..) => "module",
+            ItemKind::ForeignMod { .. } => "extern block",
+            ItemKind::GlobalAsm(..) => "global asm item",
+            ItemKind::TyAlias(..) => "type alias",
+            ItemKind::OpaqueTy(..) => "opaque type",
+            ItemKind::Enum(..) => "enum",
+            ItemKind::Struct(..) => "struct",
+            ItemKind::Union(..) => "union",
+            ItemKind::Trait(..) => "trait",
+            ItemKind::TraitAlias(..) => "trait alias",
+            ItemKind::Impl(..) => "implementation",
+        }
+    }
 }
 
 /// A reference from an trait to one of its associated items. This
diff --git a/compiler/rustc_typeck/src/astconv/mod.rs b/compiler/rustc_typeck/src/astconv/mod.rs
index ef195621044..10a7d69d5d3 100644
--- a/compiler/rustc_typeck/src/astconv/mod.rs
+++ b/compiler/rustc_typeck/src/astconv/mod.rs
@@ -2418,6 +2418,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 visitor.0,
                 true,
                 hir_ty,
+                "function",
             );
         }
 
diff --git a/compiler/rustc_typeck/src/collect.rs b/compiler/rustc_typeck/src/collect.rs
index ae61dd1cfce..91e65cffc58 100644
--- a/compiler/rustc_typeck/src/collect.rs
+++ b/compiler/rustc_typeck/src/collect.rs
@@ -145,6 +145,7 @@ crate fn placeholder_type_error(
     placeholder_types: Vec<Span>,
     suggest: bool,
     hir_ty: Option<&hir::Ty<'_>>,
+    kind: &'static str,
 ) {
     if placeholder_types.is_empty() {
         return;
@@ -174,7 +175,7 @@ crate fn placeholder_type_error(
         ));
     }
 
-    let mut err = bad_placeholder_type(tcx, placeholder_types);
+    let mut err = bad_placeholder_type(tcx, placeholder_types, kind);
 
     // Suggest, but only if it is not a function in const or static
     if suggest {
@@ -236,7 +237,15 @@ 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, Some(generics.span), generics.params, visitor.0, suggest, None);
+    placeholder_type_error(
+        tcx,
+        Some(generics.span),
+        generics.params,
+        visitor.0,
+        suggest,
+        None,
+        item.kind.descr(),
+    );
 }
 
 impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
@@ -302,13 +311,17 @@ impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
 fn bad_placeholder_type(
     tcx: TyCtxt<'tcx>,
     mut spans: Vec<Span>,
+    kind: &'static str,
 ) -> rustc_errors::DiagnosticBuilder<'tcx> {
+    let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
+
     spans.sort();
     let mut err = struct_span_err!(
         tcx.sess,
         spans.clone(),
         E0121,
-        "the type placeholder `_` is not allowed within types on item signatures",
+        "the type placeholder `_` is not allowed within types on item signatures for {}",
+        kind
     );
     for span in spans {
         err.span_label(span, "not allowed in type signatures");
@@ -382,7 +395,7 @@ impl AstConv<'tcx> for ItemCtxt<'tcx> {
         _: Option<&ty::GenericParamDef>,
         span: Span,
     ) -> &'tcx Const<'tcx> {
-        bad_placeholder_type(self.tcx(), vec![span]).emit();
+        bad_placeholder_type(self.tcx(), vec![span], "generic").emit();
         // Typeck doesn't expect erased regions to be returned from `type_of`.
         let ty = self.tcx.fold_regions(ty, &mut false, |r, _| match r {
             ty::ReErased => self.tcx.lifetimes.re_static,
@@ -746,7 +759,15 @@ fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
                     hir::ForeignItemKind::Static(..) => {
                         let mut visitor = PlaceholderHirTyCollector::default();
                         visitor.visit_foreign_item(item);
-                        placeholder_type_error(tcx, None, &[], visitor.0, false, None);
+                        placeholder_type_error(
+                            tcx,
+                            None,
+                            &[],
+                            visitor.0,
+                            false,
+                            None,
+                            "static variable",
+                        );
                     }
                     _ => (),
                 }
@@ -818,7 +839,15 @@ fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
                     if let hir::TyKind::TraitObject(..) = ty.kind {
                         let mut visitor = PlaceholderHirTyCollector::default();
                         visitor.visit_item(it);
-                        placeholder_type_error(tcx, None, &[], visitor.0, false, None);
+                        placeholder_type_error(
+                            tcx,
+                            None,
+                            &[],
+                            visitor.0,
+                            false,
+                            None,
+                            it.kind.descr(),
+                        );
                     }
                 }
                 _ => (),
@@ -846,7 +875,7 @@ fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
             // Account for `const C: _;`.
             let mut visitor = PlaceholderHirTyCollector::default();
             visitor.visit_trait_item(trait_item);
-            placeholder_type_error(tcx, None, &[], visitor.0, false, None);
+            placeholder_type_error(tcx, None, &[], visitor.0, false, None, "constant");
         }
 
         hir::TraitItemKind::Type(_, Some(_)) => {
@@ -855,7 +884,7 @@ fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
             // Account for `type T = _;`.
             let mut visitor = PlaceholderHirTyCollector::default();
             visitor.visit_trait_item(trait_item);
-            placeholder_type_error(tcx, None, &[], visitor.0, false, None);
+            placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
         }
 
         hir::TraitItemKind::Type(_, None) => {
@@ -865,7 +894,7 @@ fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
             let mut visitor = PlaceholderHirTyCollector::default();
             visitor.visit_trait_item(trait_item);
 
-            placeholder_type_error(tcx, None, &[], visitor.0, false, None);
+            placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
         }
     };
 
@@ -887,7 +916,7 @@ fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
             let mut visitor = PlaceholderHirTyCollector::default();
             visitor.visit_impl_item(impl_item);
 
-            placeholder_type_error(tcx, None, &[], visitor.0, false, None);
+            placeholder_type_error(tcx, None, &[], visitor.0, false, None, "associated type");
         }
         hir::ImplItemKind::Const(..) => {}
     }
@@ -1711,7 +1740,7 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
 
                     let mut visitor = PlaceholderHirTyCollector::default();
                     visitor.visit_ty(ty);
-                    let mut diag = bad_placeholder_type(tcx, visitor.0);
+                    let mut diag = bad_placeholder_type(tcx, visitor.0, "return type");
                     let ret_ty = fn_sig.output();
                     if ret_ty != tcx.ty_error() {
                         if !ret_ty.is_closure() {
diff --git a/compiler/rustc_typeck/src/collect/type_of.rs b/compiler/rustc_typeck/src/collect/type_of.rs
index abe5d69a3b3..78fa8074a64 100644
--- a/compiler/rustc_typeck/src/collect/type_of.rs
+++ b/compiler/rustc_typeck/src/collect/type_of.rs
@@ -285,7 +285,9 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
             TraitItemKind::Const(ref ty, body_id) => body_id
                 .and_then(|body_id| {
                     if is_suggestable_infer_ty(ty) {
-                        Some(infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident))
+                        Some(infer_placeholder_type(
+                            tcx, def_id, body_id, ty.span, item.ident, "constant",
+                        ))
                     } else {
                         None
                     }
@@ -304,7 +306,7 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
             }
             ImplItemKind::Const(ref ty, body_id) => {
                 if is_suggestable_infer_ty(ty) {
-                    infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
+                    infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident, "constant")
                 } else {
                     icx.to_ty(ty)
                 }
@@ -320,9 +322,25 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
 
         Node::Item(item) => {
             match item.kind {
-                ItemKind::Static(ref ty, .., body_id) | ItemKind::Const(ref ty, body_id) => {
+                ItemKind::Static(ref ty, .., body_id) => {
                     if is_suggestable_infer_ty(ty) {
-                        infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
+                        infer_placeholder_type(
+                            tcx,
+                            def_id,
+                            body_id,
+                            ty.span,
+                            item.ident,
+                            "static variable",
+                        )
+                    } else {
+                        icx.to_ty(ty)
+                    }
+                }
+                ItemKind::Const(ref ty, body_id) => {
+                    if is_suggestable_infer_ty(ty) {
+                        infer_placeholder_type(
+                            tcx, def_id, body_id, ty.span, item.ident, "constant",
+                        )
                     } else {
                         icx.to_ty(ty)
                     }
@@ -742,13 +760,14 @@ fn let_position_impl_trait_type(tcx: TyCtxt<'_>, opaque_ty_id: LocalDefId) -> Ty
     concrete_ty
 }
 
-fn infer_placeholder_type(
-    tcx: TyCtxt<'_>,
+fn infer_placeholder_type<'a>(
+    tcx: TyCtxt<'a>,
     def_id: LocalDefId,
     body_id: hir::BodyId,
     span: Span,
     item_ident: Ident,
-) -> Ty<'_> {
+    kind: &'static str,
+) -> Ty<'a> {
     // Attempts to make the type nameable by turning FnDefs into FnPtrs.
     struct MakeNameable<'tcx> {
         success: bool,
@@ -802,7 +821,7 @@ fn infer_placeholder_type(
             if let Some(sugg_ty) = sugg_ty {
                 err.span_suggestion(
                     span,
-                    "provide a type for the item",
+                    &format!("provide a type for the {item}", item = kind),
                     format!("{}: {}", item_ident, sugg_ty),
                     Applicability::MachineApplicable,
                 );
@@ -816,7 +835,7 @@ fn infer_placeholder_type(
             err.emit_unless(ty.references_error());
         }
         None => {
-            let mut diag = bad_placeholder_type(tcx, vec![span]);
+            let mut diag = bad_placeholder_type(tcx, vec![span], kind);
 
             if !ty.references_error() {
                 let mut mk_nameable = MakeNameable::new(tcx);
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 99ebe84cd9d..1b6bcfbb9fc 100644
--- a/src/test/ui/did_you_mean/bad-assoc-ty.rs
+++ b/src/test/ui/did_you_mean/bad-assoc-ty.rs
@@ -16,7 +16,7 @@ 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 for type aliases
 
 type F = &'static (u8)::AssocTy;
 //~^ ERROR missing angle brackets in associated item path
@@ -47,37 +47,37 @@ type I = ty!()::AssocTy;
 
 trait K<A, B> {}
 fn foo<X: K<_, _>>(x: 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 for functions
 
 fn bar<F>(_: F) where 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 for functions
 
 fn baz<F: Fn() -> _>(_: F) {}
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
 
 struct L<F>(F) where 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 for structs
 struct M<F> where 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 for structs
     a: F,
 }
 enum N<F> where 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 for enums
     Foo(F),
 }
 
 union O<F> where 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 for unions
     foo: F,
 }
 
 trait P<F> where 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 for traits
 }
 
 trait Q {
     fn foo<F>(_: F) where 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 for functions
 }
 
 fn main() {}
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 fc5f218c04f..8db9652b1ea 100644
--- a/src/test/ui/did_you_mean/bad-assoc-ty.stderr
+++ b/src/test/ui/did_you_mean/bad-assoc-ty.stderr
@@ -81,7 +81,7 @@ error[E0223]: ambiguous associated type
 LL | type D = (u8, u8)::AssocTy;
    |          ^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<(u8, u8) as Trait>::AssocTy`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for type aliases
   --> $DIR/bad-assoc-ty.rs:17:10
    |
 LL | type E = _::AssocTy;
@@ -122,7 +122,7 @@ error[E0223]: ambiguous associated type
 LL | type I = ty!()::AssocTy;
    |          ^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<u8 as Trait>::AssocTy`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/bad-assoc-ty.rs:49:13
    |
 LL | fn foo<X: K<_, _>>(x: X) {}
@@ -135,7 +135,7 @@ help: use type parameters instead
 LL | fn foo<X: K<T, T>, T>(x: X) {}
    |             ^  ^ ^^^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/bad-assoc-ty.rs:52:34
    |
 LL | fn bar<F>(_: F) where F: Fn() -> _ {}
@@ -146,7 +146,7 @@ help: use type parameters instead
 LL | fn bar<F, T>(_: F) where F: Fn() -> T {}
    |         ^^^                         ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/bad-assoc-ty.rs:55:19
    |
 LL | fn baz<F: Fn() -> _>(_: F) {}
@@ -157,7 +157,7 @@ help: use type parameters instead
 LL | fn baz<F: Fn() -> T, T>(_: F) {}
    |                   ^^^^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
   --> $DIR/bad-assoc-ty.rs:58:33
    |
 LL | struct L<F>(F) where F: Fn() -> _;
@@ -168,7 +168,7 @@ help: use type parameters instead
 LL | struct L<F, T>(F) where F: Fn() -> T;
    |           ^^^                      ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
   --> $DIR/bad-assoc-ty.rs:60:30
    |
 LL | struct M<F> where F: Fn() -> _ {
@@ -179,7 +179,7 @@ help: use type parameters instead
 LL | struct M<F, T> where F: Fn() -> T {
    |           ^^^                   ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for enums
   --> $DIR/bad-assoc-ty.rs:64:28
    |
 LL | enum N<F> where F: Fn() -> _ {
@@ -190,7 +190,7 @@ help: use type parameters instead
 LL | enum N<F, T> where F: Fn() -> T {
    |         ^^^                   ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for unions
   --> $DIR/bad-assoc-ty.rs:69:29
    |
 LL | union O<F> where F: Fn() -> _ {
@@ -201,7 +201,7 @@ help: use type parameters instead
 LL | union O<F, T> where F: Fn() -> T {
    |          ^^^                   ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for traits
   --> $DIR/bad-assoc-ty.rs:74:29
    |
 LL | trait P<F> where F: Fn() -> _ {
@@ -212,7 +212,7 @@ help: use type parameters instead
 LL | trait P<F, T> where F: Fn() -> T {
    |          ^^^                   ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/bad-assoc-ty.rs:79:38
    |
 LL |     fn foo<F>(_: F) where F: Fn() -> _ {}
diff --git a/src/test/ui/error-codes/E0121.stderr b/src/test/ui/error-codes/E0121.stderr
index 246f69558ff..cc0c2df72ea 100644
--- a/src/test/ui/error-codes/E0121.stderr
+++ b/src/test/ui/error-codes/E0121.stderr
@@ -1,4 +1,4 @@
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/E0121.rs:1:13
    |
 LL | fn foo() -> _ { 5 }
@@ -7,7 +7,7 @@ LL | fn foo() -> _ { 5 }
    |             not allowed in type signatures
    |             help: replace with the correct return type: `i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/E0121.rs:3:13
    |
 LL | static BAR: _ = "test";
diff --git a/src/test/ui/fn/issue-80179.rs b/src/test/ui/fn/issue-80179.rs
index 7609b1525cc..550974bf778 100644
--- a/src/test/ui/fn/issue-80179.rs
+++ b/src/test/ui/fn/issue-80179.rs
@@ -8,7 +8,7 @@ fn returns_i32() -> i32 {
 }
 
 fn returns_fn_ptr() -> _ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures [E0121]
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types [E0121]
 //~| NOTE not allowed in type signatures
 //~| HELP replace with the correct return type
 //~| SUGGESTION fn() -> i32
@@ -16,7 +16,7 @@ fn returns_fn_ptr() -> _ {
 }
 
 fn returns_closure() -> _ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures [E0121]
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types [E0121]
 //~| NOTE not allowed in type signatures
 //~| HELP consider using an `Fn`, `FnMut`, or `FnOnce` trait bound
 //~| NOTE for more information on `Fn` traits and closure types, see
diff --git a/src/test/ui/fn/issue-80179.stderr b/src/test/ui/fn/issue-80179.stderr
index 63571e71b34..96d0f02b01a 100644
--- a/src/test/ui/fn/issue-80179.stderr
+++ b/src/test/ui/fn/issue-80179.stderr
@@ -1,4 +1,4 @@
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-80179.rs:10:24
    |
 LL | fn returns_fn_ptr() -> _ {
@@ -7,7 +7,7 @@ LL | fn returns_fn_ptr() -> _ {
    |                        not allowed in type signatures
    |                        help: replace with the correct return type: `fn() -> i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-80179.rs:18:25
    |
 LL | fn returns_closure() -> _ {
diff --git a/src/test/ui/issues/issue-69396-const-no-type-in-macro.rs b/src/test/ui/issues/issue-69396-const-no-type-in-macro.rs
index 69fc0c1cbb9..6880e1a4629 100644
--- a/src/test/ui/issues/issue-69396-const-no-type-in-macro.rs
+++ b/src/test/ui/issues/issue-69396-const-no-type-in-macro.rs
@@ -4,7 +4,7 @@ macro_rules! suite {
             const A = "A".$fn();
             //~^ ERROR the name `A` is defined multiple times
             //~| ERROR missing type for `const` item
-            //~| ERROR the type placeholder `_` is not allowed within types
+            //~| ERROR the type placeholder `_` is not allowed within types on item signatures for constants
         )*
     }
 }
diff --git a/src/test/ui/issues/issue-69396-const-no-type-in-macro.stderr b/src/test/ui/issues/issue-69396-const-no-type-in-macro.stderr
index a84c048fab9..34c2073db04 100644
--- a/src/test/ui/issues/issue-69396-const-no-type-in-macro.stderr
+++ b/src/test/ui/issues/issue-69396-const-no-type-in-macro.stderr
@@ -20,7 +20,7 @@ error: missing type for `const` item
   --> $DIR/issue-69396-const-no-type-in-macro.rs:4:19
    |
 LL |               const A = "A".$fn();
-   |                     ^ help: provide a type for the item: `A: usize`
+   |                     ^ help: provide a type for the constant: `A: usize`
 ...
 LL | / suite! {
 LL | |     len;
@@ -30,7 +30,7 @@ LL | | }
    |
    = note: this error originates in the macro `suite` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/issue-69396-const-no-type-in-macro.rs:4:19
    |
 LL |               const A = "A".$fn();
diff --git a/src/test/ui/self/self-infer.rs b/src/test/ui/self/self-infer.rs
index 0956f2a5691..cc17d8f8e39 100644
--- a/src/test/ui/self/self-infer.rs
+++ b/src/test/ui/self/self-infer.rs
@@ -1,8 +1,8 @@
 struct S;
 
 impl S {
-    fn f(self: _) {} //~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
+    fn f(self: _) {} //~ERROR the type placeholder `_` is not allowed within types on item signatures for functions
+    fn g(self: &_) {} //~ERROR the type placeholder `_` is not allowed within types on item signatures for functions
 }
 
 fn main() {}
diff --git a/src/test/ui/self/self-infer.stderr b/src/test/ui/self/self-infer.stderr
index 1475b212b56..8d70c6287e5 100644
--- a/src/test/ui/self/self-infer.stderr
+++ b/src/test/ui/self/self-infer.stderr
@@ -1,4 +1,4 @@
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/self-infer.rs:4:16
    |
 LL |     fn f(self: _) {}
@@ -9,7 +9,7 @@ help: use type parameters instead
 LL |     fn f<T>(self: T) {}
    |         ^^^       ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/self-infer.rs:5:17
    |
 LL |     fn g(self: &_) {}
diff --git a/src/test/ui/suggestions/const-no-type.rs b/src/test/ui/suggestions/const-no-type.rs
index 2ffb24c6e6c..6f46cfdf024 100644
--- a/src/test/ui/suggestions/const-no-type.rs
+++ b/src/test/ui/suggestions/const-no-type.rs
@@ -32,20 +32,20 @@ static mut SM2 = "abc";
 
 const C = 42;
 //~^ ERROR missing type for `const` item
-//~| HELP provide a type for the item
+//~| HELP provide a type for the constant
 //~| SUGGESTION C: i32
 
 const D = &&42;
 //~^ ERROR missing type for `const` item
-//~| HELP provide a type for the item
+//~| HELP provide a type for the constant
 //~| SUGGESTION D: &&i32
 
 static S = Vec::<String>::new();
 //~^ ERROR missing type for `static` item
-//~| HELP provide a type for the item
+//~| HELP provide a type for the static variable
 //~| SUGGESTION S: Vec<String>
 
 static mut SM = "abc";
 //~^ ERROR missing type for `static mut` item
-//~| HELP provide a type for the item
+//~| HELP provide a type for the static variable
 //~| SUGGESTION &str
diff --git a/src/test/ui/suggestions/const-no-type.stderr b/src/test/ui/suggestions/const-no-type.stderr
index b180a6a9a9b..3b0fd6337f1 100644
--- a/src/test/ui/suggestions/const-no-type.stderr
+++ b/src/test/ui/suggestions/const-no-type.stderr
@@ -2,25 +2,25 @@ error: missing type for `const` item
   --> $DIR/const-no-type.rs:33:7
    |
 LL | const C = 42;
-   |       ^ help: provide a type for the item: `C: i32`
+   |       ^ help: provide a type for the constant: `C: i32`
 
 error: missing type for `const` item
   --> $DIR/const-no-type.rs:38:7
    |
 LL | const D = &&42;
-   |       ^ help: provide a type for the item: `D: &&i32`
+   |       ^ help: provide a type for the constant: `D: &&i32`
 
 error: missing type for `static` item
   --> $DIR/const-no-type.rs:43:8
    |
 LL | static S = Vec::<String>::new();
-   |        ^ help: provide a type for the item: `S: Vec<String>`
+   |        ^ help: provide a type for the static variable: `S: Vec<String>`
 
 error: missing type for `static mut` item
   --> $DIR/const-no-type.rs:48:12
    |
 LL | static mut SM = "abc";
-   |            ^^ help: provide a type for the item: `SM: &str`
+   |            ^^ help: provide a type for the static variable: `SM: &str`
 
 error: missing type for `const` item
   --> $DIR/const-no-type.rs:14:7
diff --git a/src/test/ui/suggestions/unnamable-types.rs b/src/test/ui/suggestions/unnamable-types.rs
index 5d0616443e5..483f9bbb48c 100644
--- a/src/test/ui/suggestions/unnamable-types.rs
+++ b/src/test/ui/suggestions/unnamable-types.rs
@@ -5,17 +5,17 @@
 
 const A = 5;
 //~^ ERROR: missing type for `const` item
-//~| HELP: provide a type for the item
+//~| HELP: provide a type for the constant
 
 static B: _ = "abc";
-//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures for static variables
 //~| NOTE: not allowed in type signatures
 //~| HELP: replace with the correct type
 
 
 // FIXME: this should also suggest a function pointer, as the closure is non-capturing
 const C: _ = || 42;
-//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures for constants
 //~| NOTE: not allowed in type signatures
 //~| NOTE: however, the inferred type
 
@@ -28,10 +28,10 @@ const D = S { t: { let i = 0; move || -> i32 { i } } };
 fn foo() -> i32 { 42 }
 const E = foo;
 //~^ ERROR: missing type for `const` item
-//~| HELP: provide a type for the item
+//~| HELP: provide a type for the constant
 const F = S { t: foo };
 //~^ ERROR: missing type for `const` item
-//~| HELP: provide a type for the item
+//~| HELP: provide a type for the constant
 
 
 const G = || -> i32 { yield 0; return 1; };
diff --git a/src/test/ui/suggestions/unnamable-types.stderr b/src/test/ui/suggestions/unnamable-types.stderr
index 05a7baa68ba..3a489a6e943 100644
--- a/src/test/ui/suggestions/unnamable-types.stderr
+++ b/src/test/ui/suggestions/unnamable-types.stderr
@@ -2,9 +2,9 @@ error: missing type for `const` item
   --> $DIR/unnamable-types.rs:6:7
    |
 LL | const A = 5;
-   |       ^ help: provide a type for the item: `A: i32`
+   |       ^ help: provide a type for the constant: `A: i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/unnamable-types.rs:10:11
    |
 LL | static B: _ = "abc";
@@ -13,7 +13,7 @@ LL | static B: _ = "abc";
    |           not allowed in type signatures
    |           help: replace with the correct type: `&str`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/unnamable-types.rs:17:10
    |
 LL | const C: _ = || 42;
@@ -41,13 +41,13 @@ error: missing type for `const` item
   --> $DIR/unnamable-types.rs:29:7
    |
 LL | const E = foo;
-   |       ^ help: provide a type for the item: `E: fn() -> i32`
+   |       ^ help: provide a type for the constant: `E: fn() -> i32`
 
 error: missing type for `const` item
   --> $DIR/unnamable-types.rs:32:7
    |
 LL | const F = S { t: foo };
-   |       ^ help: provide a type for the item: `F: S<fn() -> i32>`
+   |       ^ help: provide a type for the constant: `F: S<fn() -> i32>`
 
 error: missing type for `const` item
   --> $DIR/unnamable-types.rs:37:7
diff --git a/src/test/ui/typeck/issue-74086.rs b/src/test/ui/typeck/issue-74086.rs
index f68a665b2f3..1de9cd8007c 100644
--- a/src/test/ui/typeck/issue-74086.rs
+++ b/src/test/ui/typeck/issue-74086.rs
@@ -1,4 +1,4 @@
 fn main() {
     static BUG: fn(_) -> u8 = |_| 8;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures [E0121]
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions [E0121]
 }
diff --git a/src/test/ui/typeck/issue-74086.stderr b/src/test/ui/typeck/issue-74086.stderr
index e602425059e..ac1752e17df 100644
--- a/src/test/ui/typeck/issue-74086.stderr
+++ b/src/test/ui/typeck/issue-74086.stderr
@@ -1,4 +1,4 @@
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/issue-74086.rs:2:20
    |
 LL |     static BUG: fn(_) -> u8 = |_| 8;
diff --git a/src/test/ui/typeck/issue-75883.rs b/src/test/ui/typeck/issue-75883.rs
index 8cd34f48835..0d1534df091 100644
--- a/src/test/ui/typeck/issue-75883.rs
+++ b/src/test/ui/typeck/issue-75883.rs
@@ -5,7 +5,7 @@ pub struct UI {}
 impl UI {
     pub fn run() -> Result<_> {
         //~^ ERROR: this enum takes 2 generic arguments but 1 generic argument was supplied
-        //~| ERROR: the type placeholder `_` is not allowed within types on item signatures
+        //~| ERROR: the type placeholder `_` is not allowed within types on item signatures for return types
         let mut ui = UI {};
         ui.interact();
 
@@ -14,7 +14,7 @@ impl UI {
 
     pub fn interact(&mut self) -> Result<_> {
         //~^ ERROR: this enum takes 2 generic arguments but 1 generic argument was supplied
-        //~| ERROR: the type placeholder `_` is not allowed within types on item signatures
+        //~| ERROR: the type placeholder `_` is not allowed within types on item signatures for return types
         unimplemented!();
     }
 }
diff --git a/src/test/ui/typeck/issue-75883.stderr b/src/test/ui/typeck/issue-75883.stderr
index 71f4138c81d..a722c4b5e3e 100644
--- a/src/test/ui/typeck/issue-75883.stderr
+++ b/src/test/ui/typeck/issue-75883.stderr
@@ -34,13 +34,13 @@ help: add missing generic argument
 LL |     pub fn interact(&mut self) -> Result<_, E> {
    |                                           ^^^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-75883.rs:15:42
    |
 LL |     pub fn interact(&mut self) -> Result<_> {
    |                                          ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-75883.rs:6:28
    |
 LL |     pub fn run() -> Result<_> {
diff --git a/src/test/ui/typeck/issue-75889.stderr b/src/test/ui/typeck/issue-75889.stderr
index 0a8a3c9e743..de4bdf4e6d9 100644
--- a/src/test/ui/typeck/issue-75889.stderr
+++ b/src/test/ui/typeck/issue-75889.stderr
@@ -1,10 +1,10 @@
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constant items
   --> $DIR/issue-75889.rs:3:24
    |
 LL | const FOO: dyn Fn() -> _ = "";
    |                        ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static items
   --> $DIR/issue-75889.rs:4:25
    |
 LL | static BOO: dyn Fn() -> _ = "";
diff --git a/src/test/ui/typeck/issue-80779.rs b/src/test/ui/typeck/issue-80779.rs
index 6791976196f..99a93b1863d 100644
--- a/src/test/ui/typeck/issue-80779.rs
+++ b/src/test/ui/typeck/issue-80779.rs
@@ -3,11 +3,11 @@
 pub struct T<'a>(&'a str);
 
 pub fn f<'a>(val: T<'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 for return types
     g(val)
 }
 
 pub fn g(_: T<'static>) -> _ {}
-//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures for return types
 
 fn main() {}
diff --git a/src/test/ui/typeck/issue-80779.stderr b/src/test/ui/typeck/issue-80779.stderr
index aca494520f8..5a695fecc29 100644
--- a/src/test/ui/typeck/issue-80779.stderr
+++ b/src/test/ui/typeck/issue-80779.stderr
@@ -1,4 +1,4 @@
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-80779.rs:10:28
    |
 LL | pub fn g(_: T<'static>) -> _ {}
@@ -7,7 +7,7 @@ LL | pub fn g(_: T<'static>) -> _ {}
    |                            not allowed in type signatures
    |                            help: replace with the correct return type: `()`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/issue-80779.rs:5:29
    |
 LL | pub fn f<'a>(val: T<'a>) -> _ {
diff --git a/src/test/ui/typeck/issue-81885.rs b/src/test/ui/typeck/issue-81885.rs
index 86c39d4a48c..5117f250fe5 100644
--- a/src/test/ui/typeck/issue-81885.rs
+++ b/src/test/ui/typeck/issue-81885.rs
@@ -1,10 +1,8 @@
 const TEST4: fn() -> _ = 42;
-                  //~^ ERROR the type placeholder `_` is not allowed within types on item
-                  //signatures
+                  //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
 
 fn main() {
     const TEST5: fn() -> _ = 42;
-                      //~^ ERROR the type placeholder `_` is not allowed within types on item
-                      //signatures
+                      //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
 
 }
diff --git a/src/test/ui/typeck/issue-81885.stderr b/src/test/ui/typeck/issue-81885.stderr
index 955b4283874..8206156a618 100644
--- a/src/test/ui/typeck/issue-81885.stderr
+++ b/src/test/ui/typeck/issue-81885.stderr
@@ -1,11 +1,11 @@
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/issue-81885.rs:1:22
    |
 LL | const TEST4: fn() -> _ = 42;
    |                      ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/issue-81885.rs:6:26
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/issue-81885.rs:5:26
    |
 LL |     const TEST5: fn() -> _ = 42;
    |                          ^ not allowed in type signatures
diff --git a/src/test/ui/typeck/issue-83621-placeholder-static-in-extern.stderr b/src/test/ui/typeck/issue-83621-placeholder-static-in-extern.stderr
index b1bec4c0827..7c5cf1082be 100644
--- a/src/test/ui/typeck/issue-83621-placeholder-static-in-extern.stderr
+++ b/src/test/ui/typeck/issue-83621-placeholder-static-in-extern.stderr
@@ -1,4 +1,4 @@
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/issue-83621-placeholder-static-in-extern.rs:4:15
    |
 LL |     static x: _;
diff --git a/src/test/ui/typeck/type-placeholder-fn-in-const.rs b/src/test/ui/typeck/type-placeholder-fn-in-const.rs
index c27edc8485b..f657bea1648 100644
--- a/src/test/ui/typeck/type-placeholder-fn-in-const.rs
+++ b/src/test/ui/typeck/type-placeholder-fn-in-const.rs
@@ -2,13 +2,13 @@ struct MyStruct;
 
 trait Test {
     const TEST: fn() -> _;
-    //~^ ERROR: the type placeholder `_` is not allowed within types on item signatures [E0121]
-    //~| ERROR: the type placeholder `_` is not allowed within types on item signatures [E0121]
+    //~^ ERROR: the type placeholder `_` is not allowed within types on item signatures for functions [E0121]
+    //~| ERROR: the type placeholder `_` is not allowed within types on item signatures for constants [E0121]
 }
 
 impl Test for MyStruct {
     const TEST: fn() -> _ = 42;
-    //~^ ERROR: the type placeholder `_` is not allowed within types on item signatures [E0121]
+    //~^ ERROR: the type placeholder `_` is not allowed within types on item signatures for functions [E0121]
 }
 
 fn main() {}
diff --git a/src/test/ui/typeck/type-placeholder-fn-in-const.stderr b/src/test/ui/typeck/type-placeholder-fn-in-const.stderr
index 662871779a1..62f4db8638f 100644
--- a/src/test/ui/typeck/type-placeholder-fn-in-const.stderr
+++ b/src/test/ui/typeck/type-placeholder-fn-in-const.stderr
@@ -1,16 +1,16 @@
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/type-placeholder-fn-in-const.rs:4:25
    |
 LL |     const TEST: fn() -> _;
    |                         ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/type-placeholder-fn-in-const.rs:4:25
    |
 LL |     const TEST: fn() -> _;
    |                         ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/type-placeholder-fn-in-const.rs:10:25
    |
 LL |     const TEST: fn() -> _ = 42;
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.full_tait.stderr b/src/test/ui/typeck/typeck_type_placeholder_item.full_tait.stderr
index bd7cbd444d7..b6aea9586b8 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item.full_tait.stderr
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.full_tait.stderr
@@ -1,35 +1,35 @@
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:158:18
+  --> $DIR/typeck_type_placeholder_item.rs:157:18
    |
 LL | struct BadStruct<_>(_);
    |                  ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:161:16
+  --> $DIR/typeck_type_placeholder_item.rs:160:16
    |
 LL | trait BadTrait<_> {}
    |                ^ 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:170:19
    |
 LL | struct BadStruct1<_, _>(_);
    |                   ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:171:22
+  --> $DIR/typeck_type_placeholder_item.rs:170:22
    |
 LL | struct BadStruct1<_, _>(_);
    |                      ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:176:19
+  --> $DIR/typeck_type_placeholder_item.rs:175:19
    |
 LL | struct BadStruct2<_, T>(_, T);
    |                   ^ expected identifier, found reserved identifier
 
 error: associated constant in `impl` without body
-  --> $DIR/typeck_type_placeholder_item.rs:209:5
+  --> $DIR/typeck_type_placeholder_item.rs:208:5
    |
 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:171:22
+  --> $DIR/typeck_type_placeholder_item.rs:170:22
    |
 LL | struct BadStruct1<_, _>(_);
    |                   -  ^ already used
@@ -53,7 +53,7 @@ LL | #![cfg_attr(full_tait, feature(type_alias_impl_trait))]
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:10:14
    |
 LL | fn test() -> _ { 5 }
@@ -62,7 +62,7 @@ LL | fn test() -> _ { 5 }
    |              not allowed in type signatures
    |              help: replace with the correct return type: `i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:13:16
    |
 LL | fn test2() -> (_, _) { (5, 5) }
@@ -72,7 +72,7 @@ LL | fn test2() -> (_, _) { (5, 5) }
    |               |not allowed in type signatures
    |               help: replace with the correct return type: `(i32, i32)`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/typeck_type_placeholder_item.rs:16:15
    |
 LL | static TEST3: _ = "test";
@@ -81,7 +81,7 @@ LL | static TEST3: _ = "test";
    |               not allowed in type signatures
    |               help: replace with the correct type: `&str`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/typeck_type_placeholder_item.rs:19:15
    |
 LL | static TEST4: _ = 145;
@@ -90,13 +90,13 @@ LL | static TEST4: _ = 145;
    |               not allowed in type signatures
    |               help: replace with the correct type: `i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/typeck_type_placeholder_item.rs:22:15
    |
 LL | static TEST5: (_, _) = (1, 2);
    |               ^^^^^^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:25:13
    |
 LL | fn test6(_: _) { }
@@ -107,7 +107,7 @@ help: use type parameters instead
 LL | fn test6<T>(_: T) { }
    |         ^^^    ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:28:18
    |
 LL | fn test6_b<T>(_: _, _: T) { }
@@ -118,7 +118,7 @@ help: use type parameters instead
 LL | fn test6_b<T, U>(_: U, _: T) { }
    |             ^^^     ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:31:30
    |
 LL | fn test6_c<T, K, L, A, B>(_: _, _: (T, K, L, A, B)) { }
@@ -129,7 +129,7 @@ help: use type parameters instead
 LL | fn test6_c<T, K, L, A, B, U>(_: U, _: (T, K, L, A, B)) { }
    |                         ^^^     ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:34:13
    |
 LL | fn test7(x: _) { let _x: usize = x; }
@@ -140,7 +140,7 @@ help: use type parameters instead
 LL | fn test7<T>(x: T) { let _x: usize = x; }
    |         ^^^    ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:37:22
    |
 LL | fn test8(_f: fn() -> _) { }
@@ -149,7 +149,7 @@ 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
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:37:22
    |
 LL | fn test8(_f: fn() -> _) { }
@@ -160,7 +160,7 @@ help: use type parameters instead
 LL | fn test8<T>(_f: fn() -> T) { }
    |         ^^^             ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:51:26
    |
 LL | fn test11(x: &usize) -> &_ {
@@ -169,7 +169,7 @@ LL | fn test11(x: &usize) -> &_ {
    |                         |not allowed in type signatures
    |                         help: replace with the correct return type: `&'static &'static usize`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:56:52
    |
 LL | unsafe fn test12(x: *const usize) -> *const *const _ {
@@ -178,7 +178,7 @@ LL | unsafe fn test12(x: *const usize) -> *const *const _ {
    |                                      |             not allowed in type signatures
    |                                      help: replace with the correct return type: `*const *const usize`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
   --> $DIR/typeck_type_placeholder_item.rs:70:8
    |
 LL |     a: _,
@@ -201,9 +201,9 @@ error: missing type for `static` item
   --> $DIR/typeck_type_placeholder_item.rs:76:12
    |
 LL |     static A = 42;
-   |            ^ help: provide a type for the item: `A: i32`
+   |            ^ help: provide a type for the static variable: `A: i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/typeck_type_placeholder_item.rs:78:15
    |
 LL |     static B: _ = 42;
@@ -212,14 +212,14 @@ LL |     static B: _ = 42;
    |               not allowed in type signatures
    |               help: replace with the correct type: `i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/typeck_type_placeholder_item.rs:80:15
    |
 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:83:21
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:82:21
    |
 LL |     fn fn_test() -> _ { 5 }
    |                     ^
@@ -227,8 +227,8 @@ LL |     fn fn_test() -> _ { 5 }
    |                     not allowed in type signatures
    |                     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:86:23
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:85:23
    |
 LL |     fn fn_test2() -> (_, _) { (5, 5) }
    |                      -^--^-
@@ -237,8 +237,8 @@ LL |     fn fn_test2() -> (_, _) { (5, 5) }
    |                      |not allowed in type signatures
    |                      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:89:22
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:88:22
    |
 LL |     static FN_TEST3: _ = "test";
    |                      ^
@@ -246,8 +246,8 @@ LL |     static FN_TEST3: _ = "test";
    |                      not allowed in type signatures
    |                      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:92:22
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:91:22
    |
 LL |     static FN_TEST4: _ = 145;
    |                      ^
@@ -255,14 +255,14 @@ LL |     static FN_TEST4: _ = 145;
    |                      not allowed in type signatures
    |                      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:95:22
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:94:22
    |
 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:98:20
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:97:20
    |
 LL |     fn fn_test6(_: _) { }
    |                    ^ not allowed in type signatures
@@ -272,8 +272,8 @@ help: use type parameters instead
 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:101:20
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:100:20
    |
 LL |     fn fn_test7(x: _) { let _x: usize = x; }
    |                    ^ not allowed in type signatures
@@ -283,8 +283,8 @@ help: use type parameters instead
 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:104:29
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:103:29
    |
 LL |     fn fn_test8(_f: fn() -> _) { }
    |                             ^
@@ -292,8 +292,8 @@ 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:104:29
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:103:29
    |
 LL |     fn fn_test8(_f: fn() -> _) { }
    |                             ^ not allowed in type signatures
@@ -303,8 +303,8 @@ help: use type parameters instead
 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:127:12
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:126:12
    |
 LL |         a: _,
    |            ^ not allowed in type signatures
@@ -323,21 +323,21 @@ LL |         b: (T, T),
    |
 
 error[E0282]: type annotations needed
-  --> $DIR/typeck_type_placeholder_item.rs:132:18
+  --> $DIR/typeck_type_placeholder_item.rs:131:18
    |
 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:132:28
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:131:28
    |
 LL |     fn fn_test11(_: _) -> (_, _) { panic!() }
    |                            ^  ^ not allowed in type signatures
    |                            |
    |                            not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:136:30
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:135:30
    |
 LL |     fn fn_test12(x: i32) -> (_, _) { (x, x) }
    |                             -^--^-
@@ -346,8 +346,8 @@ LL |     fn fn_test12(x: i32) -> (_, _) { (x, x) }
    |                             |not allowed in type signatures
    |                             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:139:33
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:138:33
    |
 LL |     fn fn_test13(x: _) -> (i32, _) { (x, x) }
    |                           ------^-
@@ -355,8 +355,8 @@ LL |     fn fn_test13(x: _) -> (i32, _) { (x, x) }
    |                           |     not allowed in type signatures
    |                           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:158:21
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:157:21
    |
 LL | struct BadStruct<_>(_);
    |                     ^ not allowed in type signatures
@@ -366,8 +366,8 @@ help: use type parameters instead
 LL | struct BadStruct<T>(T);
    |                  ^  ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:163:15
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for implementations
+  --> $DIR/typeck_type_placeholder_item.rs:162:15
    |
 LL | impl BadTrait<_> for BadStruct<_> {}
    |               ^                ^ not allowed in type signatures
@@ -379,14 +379,14 @@ help: use type parameters instead
 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:166:34
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for opaque types
+  --> $DIR/typeck_type_placeholder_item.rs:165:34
    |
 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:171:25
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:170:25
    |
 LL | struct BadStruct1<_, _>(_);
    |                         ^ not allowed in type signatures
@@ -396,8 +396,8 @@ help: use type parameters instead
 LL | struct BadStruct1<T, _>(T);
    |                   ^     ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:176:25
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:175:25
    |
 LL | struct BadStruct2<_, T>(_, T);
    |                         ^ not allowed in type signatures
@@ -407,20 +407,20 @@ help: use type parameters instead
 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:180:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for type aliases
+  --> $DIR/typeck_type_placeholder_item.rs:179:14
    |
 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:186:21
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for opaque types
+  --> $DIR/typeck_type_placeholder_item.rs:185:21
    |
 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:220:31
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:219:31
    |
 LL | fn value() -> Option<&'static _> {
    |               ----------------^-
@@ -428,8 +428,8 @@ LL | fn value() -> Option<&'static _> {
    |               |               not allowed in type signatures
    |               help: replace with the correct return type: `Option<&'static u8>`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:225:10
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:224:10
    |
 LL | const _: Option<_> = map(value);
    |          ^^^^^^^^^
@@ -437,8 +437,8 @@ LL | const _: Option<_> = map(value);
    |          not allowed in type signatures
    |          help: replace with the correct type: `Option<u8>`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:144:31
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:143:31
    |
 LL |     fn method_test1(&self, x: _);
    |                               ^ not allowed in type signatures
@@ -448,8 +448,8 @@ help: use type parameters instead
 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:146:31
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:145:31
    |
 LL |     fn method_test2(&self, x: _) -> _;
    |                               ^     ^ not allowed in type signatures
@@ -461,8 +461,8 @@ help: use type parameters instead
 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:148:31
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:147:31
    |
 LL |     fn method_test3(&self) -> _;
    |                               ^ not allowed in type signatures
@@ -472,8 +472,8 @@ help: use type parameters instead
 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:150:26
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:149:26
    |
 LL |     fn assoc_fn_test1(x: _);
    |                          ^ not allowed in type signatures
@@ -483,8 +483,8 @@ help: use type parameters instead
 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:152:26
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:151:26
    |
 LL |     fn assoc_fn_test2(x: _) -> _;
    |                          ^     ^ not allowed in type signatures
@@ -496,8 +496,8 @@ help: use type parameters instead
 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:154:28
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:153:28
    |
 LL |     fn assoc_fn_test3() -> _;
    |                            ^ not allowed in type signatures
@@ -507,20 +507,20 @@ help: use type parameters instead
 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:194:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:193:14
    |
 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:196:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:195:14
    |
 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:198:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:197:14
    |
 LL |     const D: _ = 42;
    |              ^
@@ -528,13 +528,13 @@ LL |     const D: _ = 42;
    |              not allowed in type signatures
    |              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:201:26
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:200:26
    |
 LL |     type F: std::ops::Fn(_);
    |                          ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:44:24
    |
 LL |     fn test9(&self) -> _ { () }
@@ -543,7 +543,7 @@ LL |     fn test9(&self) -> _ { () }
    |                        not allowed in type signatures
    |                        help: replace with the correct return type: `()`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:47:27
    |
 LL |     fn test10(&self, _x : _) { }
@@ -554,7 +554,7 @@ help: use type parameters instead
 LL |     fn test10<T>(&self, _x : T) { }
    |              ^^^             ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:62:24
    |
 LL |     fn clone(&self) -> _ { Test9 }
@@ -563,7 +563,7 @@ LL |     fn clone(&self) -> _ { Test9 }
    |                        not allowed in type signatures
    |                        help: replace with the correct return type: `Test9`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:65:37
    |
 LL |     fn clone_from(&mut self, other: _) { *self = Test9; }
@@ -574,8 +574,8 @@ help: use type parameters instead
 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:111:31
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:110:31
    |
 LL |         fn fn_test9(&self) -> _ { () }
    |                               ^
@@ -583,8 +583,8 @@ LL |         fn fn_test9(&self) -> _ { () }
    |                               not allowed in type signatures
    |                               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:114:34
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:113:34
    |
 LL |         fn fn_test10(&self, _x : _) { }
    |                                  ^ not allowed in type signatures
@@ -594,8 +594,8 @@ help: use type parameters instead
 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:119:28
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:118:28
    |
 LL |         fn clone(&self) -> _ { FnTest9 }
    |                            ^
@@ -603,8 +603,8 @@ LL |         fn clone(&self) -> _ { FnTest9 }
    |                            not allowed in type signatures
    |                            help: replace with the correct return type: `FnTest9`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:122:41
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:121:41
    |
 LL |         fn clone_from(&mut self, other: _) { *self = FnTest9; }
    |                                         ^ not allowed in type signatures
@@ -614,26 +614,26 @@ help: use type parameters instead
 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:205:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:204:14
    |
 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:207:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:206:14
    |
 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:209:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:208:14
    |
 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:212:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:211:14
    |
 LL |     const D: _ = 42;
    |              ^
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.min_tait.stderr b/src/test/ui/typeck/typeck_type_placeholder_item.min_tait.stderr
index afd6aaf4e55..88cc3bfc7f8 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item.min_tait.stderr
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.min_tait.stderr
@@ -1,35 +1,35 @@
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:158:18
+  --> $DIR/typeck_type_placeholder_item.rs:157:18
    |
 LL | struct BadStruct<_>(_);
    |                  ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:161:16
+  --> $DIR/typeck_type_placeholder_item.rs:160:16
    |
 LL | trait BadTrait<_> {}
    |                ^ 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:170:19
    |
 LL | struct BadStruct1<_, _>(_);
    |                   ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:171:22
+  --> $DIR/typeck_type_placeholder_item.rs:170:22
    |
 LL | struct BadStruct1<_, _>(_);
    |                      ^ expected identifier, found reserved identifier
 
 error: expected identifier, found reserved identifier `_`
-  --> $DIR/typeck_type_placeholder_item.rs:176:19
+  --> $DIR/typeck_type_placeholder_item.rs:175:19
    |
 LL | struct BadStruct2<_, T>(_, T);
    |                   ^ expected identifier, found reserved identifier
 
 error: associated constant in `impl` without body
-  --> $DIR/typeck_type_placeholder_item.rs:209:5
+  --> $DIR/typeck_type_placeholder_item.rs:208:5
    |
 LL |     const C: _;
    |     ^^^^^^^^^^-
@@ -37,14 +37,14 @@ 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:171:22
+  --> $DIR/typeck_type_placeholder_item.rs:170:22
    |
 LL | struct BadStruct1<_, _>(_);
    |                   -  ^ already used
    |                   |
    |                   first use of `_`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:10:14
    |
 LL | fn test() -> _ { 5 }
@@ -53,7 +53,7 @@ LL | fn test() -> _ { 5 }
    |              not allowed in type signatures
    |              help: replace with the correct return type: `i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:13:16
    |
 LL | fn test2() -> (_, _) { (5, 5) }
@@ -63,7 +63,7 @@ LL | fn test2() -> (_, _) { (5, 5) }
    |               |not allowed in type signatures
    |               help: replace with the correct return type: `(i32, i32)`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/typeck_type_placeholder_item.rs:16:15
    |
 LL | static TEST3: _ = "test";
@@ -72,7 +72,7 @@ LL | static TEST3: _ = "test";
    |               not allowed in type signatures
    |               help: replace with the correct type: `&str`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/typeck_type_placeholder_item.rs:19:15
    |
 LL | static TEST4: _ = 145;
@@ -81,13 +81,13 @@ LL | static TEST4: _ = 145;
    |               not allowed in type signatures
    |               help: replace with the correct type: `i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/typeck_type_placeholder_item.rs:22:15
    |
 LL | static TEST5: (_, _) = (1, 2);
    |               ^^^^^^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:25:13
    |
 LL | fn test6(_: _) { }
@@ -98,7 +98,7 @@ help: use type parameters instead
 LL | fn test6<T>(_: T) { }
    |         ^^^    ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:28:18
    |
 LL | fn test6_b<T>(_: _, _: T) { }
@@ -109,7 +109,7 @@ help: use type parameters instead
 LL | fn test6_b<T, U>(_: U, _: T) { }
    |             ^^^     ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:31:30
    |
 LL | fn test6_c<T, K, L, A, B>(_: _, _: (T, K, L, A, B)) { }
@@ -120,7 +120,7 @@ help: use type parameters instead
 LL | fn test6_c<T, K, L, A, B, U>(_: U, _: (T, K, L, A, B)) { }
    |                         ^^^     ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:34:13
    |
 LL | fn test7(x: _) { let _x: usize = x; }
@@ -131,7 +131,7 @@ help: use type parameters instead
 LL | fn test7<T>(x: T) { let _x: usize = x; }
    |         ^^^    ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:37:22
    |
 LL | fn test8(_f: fn() -> _) { }
@@ -140,7 +140,7 @@ 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
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:37:22
    |
 LL | fn test8(_f: fn() -> _) { }
@@ -151,7 +151,7 @@ help: use type parameters instead
 LL | fn test8<T>(_f: fn() -> T) { }
    |         ^^^             ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:51:26
    |
 LL | fn test11(x: &usize) -> &_ {
@@ -160,7 +160,7 @@ LL | fn test11(x: &usize) -> &_ {
    |                         |not allowed in type signatures
    |                         help: replace with the correct return type: `&'static &'static usize`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:56:52
    |
 LL | unsafe fn test12(x: *const usize) -> *const *const _ {
@@ -169,7 +169,7 @@ LL | unsafe fn test12(x: *const usize) -> *const *const _ {
    |                                      |             not allowed in type signatures
    |                                      help: replace with the correct return type: `*const *const usize`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
   --> $DIR/typeck_type_placeholder_item.rs:70:8
    |
 LL |     a: _,
@@ -192,9 +192,9 @@ error: missing type for `static` item
   --> $DIR/typeck_type_placeholder_item.rs:76:12
    |
 LL |     static A = 42;
-   |            ^ help: provide a type for the item: `A: i32`
+   |            ^ help: provide a type for the static variable: `A: i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/typeck_type_placeholder_item.rs:78:15
    |
 LL |     static B: _ = 42;
@@ -203,14 +203,14 @@ LL |     static B: _ = 42;
    |               not allowed in type signatures
    |               help: replace with the correct type: `i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
   --> $DIR/typeck_type_placeholder_item.rs:80:15
    |
 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:83:21
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:82:21
    |
 LL |     fn fn_test() -> _ { 5 }
    |                     ^
@@ -218,8 +218,8 @@ LL |     fn fn_test() -> _ { 5 }
    |                     not allowed in type signatures
    |                     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:86:23
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:85:23
    |
 LL |     fn fn_test2() -> (_, _) { (5, 5) }
    |                      -^--^-
@@ -228,8 +228,8 @@ LL |     fn fn_test2() -> (_, _) { (5, 5) }
    |                      |not allowed in type signatures
    |                      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:89:22
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:88:22
    |
 LL |     static FN_TEST3: _ = "test";
    |                      ^
@@ -237,8 +237,8 @@ LL |     static FN_TEST3: _ = "test";
    |                      not allowed in type signatures
    |                      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:92:22
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:91:22
    |
 LL |     static FN_TEST4: _ = 145;
    |                      ^
@@ -246,14 +246,14 @@ LL |     static FN_TEST4: _ = 145;
    |                      not allowed in type signatures
    |                      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:95:22
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for static variables
+  --> $DIR/typeck_type_placeholder_item.rs:94:22
    |
 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:98:20
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:97:20
    |
 LL |     fn fn_test6(_: _) { }
    |                    ^ not allowed in type signatures
@@ -263,8 +263,8 @@ help: use type parameters instead
 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:101:20
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:100:20
    |
 LL |     fn fn_test7(x: _) { let _x: usize = x; }
    |                    ^ not allowed in type signatures
@@ -274,8 +274,8 @@ help: use type parameters instead
 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:104:29
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:103:29
    |
 LL |     fn fn_test8(_f: fn() -> _) { }
    |                             ^
@@ -283,8 +283,8 @@ 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:104:29
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:103:29
    |
 LL |     fn fn_test8(_f: fn() -> _) { }
    |                             ^ not allowed in type signatures
@@ -294,8 +294,8 @@ help: use type parameters instead
 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:127:12
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:126:12
    |
 LL |         a: _,
    |            ^ not allowed in type signatures
@@ -314,21 +314,21 @@ LL |         b: (T, T),
    |
 
 error[E0282]: type annotations needed
-  --> $DIR/typeck_type_placeholder_item.rs:132:18
+  --> $DIR/typeck_type_placeholder_item.rs:131:18
    |
 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:132:28
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:131:28
    |
 LL |     fn fn_test11(_: _) -> (_, _) { panic!() }
    |                            ^  ^ not allowed in type signatures
    |                            |
    |                            not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:136:30
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:135:30
    |
 LL |     fn fn_test12(x: i32) -> (_, _) { (x, x) }
    |                             -^--^-
@@ -337,8 +337,8 @@ LL |     fn fn_test12(x: i32) -> (_, _) { (x, x) }
    |                             |not allowed in type signatures
    |                             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:139:33
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:138:33
    |
 LL |     fn fn_test13(x: _) -> (i32, _) { (x, x) }
    |                           ------^-
@@ -346,8 +346,8 @@ LL |     fn fn_test13(x: _) -> (i32, _) { (x, x) }
    |                           |     not allowed in type signatures
    |                           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:158:21
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:157:21
    |
 LL | struct BadStruct<_>(_);
    |                     ^ not allowed in type signatures
@@ -357,8 +357,8 @@ help: use type parameters instead
 LL | struct BadStruct<T>(T);
    |                  ^  ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:163:15
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for implementations
+  --> $DIR/typeck_type_placeholder_item.rs:162:15
    |
 LL | impl BadTrait<_> for BadStruct<_> {}
    |               ^                ^ not allowed in type signatures
@@ -370,14 +370,14 @@ help: use type parameters instead
 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:166:34
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for opaque types
+  --> $DIR/typeck_type_placeholder_item.rs:165:34
    |
 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:171:25
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:170:25
    |
 LL | struct BadStruct1<_, _>(_);
    |                         ^ not allowed in type signatures
@@ -387,8 +387,8 @@ help: use type parameters instead
 LL | struct BadStruct1<T, _>(T);
    |                   ^     ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:176:25
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for structs
+  --> $DIR/typeck_type_placeholder_item.rs:175:25
    |
 LL | struct BadStruct2<_, T>(_, T);
    |                         ^ not allowed in type signatures
@@ -398,20 +398,20 @@ help: use type parameters instead
 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:180:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for type aliases
+  --> $DIR/typeck_type_placeholder_item.rs:179:14
    |
 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:186:21
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for opaque types
+  --> $DIR/typeck_type_placeholder_item.rs:185:21
    |
 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:220:31
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:219:31
    |
 LL | fn value() -> Option<&'static _> {
    |               ----------------^-
@@ -419,8 +419,8 @@ LL | fn value() -> Option<&'static _> {
    |               |               not allowed in type signatures
    |               help: replace with the correct return type: `Option<&'static u8>`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:225:10
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:224:10
    |
 LL | const _: Option<_> = map(value);
    |          ^^^^^^^^^
@@ -428,8 +428,8 @@ LL | const _: Option<_> = map(value);
    |          not allowed in type signatures
    |          help: replace with the correct type: `Option<u8>`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:144:31
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:143:31
    |
 LL |     fn method_test1(&self, x: _);
    |                               ^ not allowed in type signatures
@@ -439,8 +439,8 @@ help: use type parameters instead
 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:146:31
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:145:31
    |
 LL |     fn method_test2(&self, x: _) -> _;
    |                               ^     ^ not allowed in type signatures
@@ -452,8 +452,8 @@ help: use type parameters instead
 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:148:31
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:147:31
    |
 LL |     fn method_test3(&self) -> _;
    |                               ^ not allowed in type signatures
@@ -463,8 +463,8 @@ help: use type parameters instead
 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:150:26
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:149:26
    |
 LL |     fn assoc_fn_test1(x: _);
    |                          ^ not allowed in type signatures
@@ -474,8 +474,8 @@ help: use type parameters instead
 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:152:26
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:151:26
    |
 LL |     fn assoc_fn_test2(x: _) -> _;
    |                          ^     ^ not allowed in type signatures
@@ -487,8 +487,8 @@ help: use type parameters instead
 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:154:28
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:153:28
    |
 LL |     fn assoc_fn_test3() -> _;
    |                            ^ not allowed in type signatures
@@ -498,20 +498,20 @@ help: use type parameters instead
 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:194:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:193:14
    |
 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:196:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:195:14
    |
 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:198:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:197:14
    |
 LL |     const D: _ = 42;
    |              ^
@@ -519,13 +519,13 @@ LL |     const D: _ = 42;
    |              not allowed in type signatures
    |              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:201:26
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:200:26
    |
 LL |     type F: std::ops::Fn(_);
    |                          ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:44:24
    |
 LL |     fn test9(&self) -> _ { () }
@@ -534,7 +534,7 @@ LL |     fn test9(&self) -> _ { () }
    |                        not allowed in type signatures
    |                        help: replace with the correct return type: `()`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:47:27
    |
 LL |     fn test10(&self, _x : _) { }
@@ -545,7 +545,7 @@ help: use type parameters instead
 LL |     fn test10<T>(&self, _x : T) { }
    |              ^^^             ^
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item.rs:62:24
    |
 LL |     fn clone(&self) -> _ { Test9 }
@@ -554,7 +554,7 @@ LL |     fn clone(&self) -> _ { Test9 }
    |                        not allowed in type signatures
    |                        help: replace with the correct return type: `Test9`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item.rs:65:37
    |
 LL |     fn clone_from(&mut self, other: _) { *self = Test9; }
@@ -565,8 +565,8 @@ help: use type parameters instead
 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:111:31
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:110:31
    |
 LL |         fn fn_test9(&self) -> _ { () }
    |                               ^
@@ -574,8 +574,8 @@ LL |         fn fn_test9(&self) -> _ { () }
    |                               not allowed in type signatures
    |                               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:114:34
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:113:34
    |
 LL |         fn fn_test10(&self, _x : _) { }
    |                                  ^ not allowed in type signatures
@@ -585,8 +585,8 @@ help: use type parameters instead
 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:119:28
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/typeck_type_placeholder_item.rs:118:28
    |
 LL |         fn clone(&self) -> _ { FnTest9 }
    |                            ^
@@ -594,8 +594,8 @@ LL |         fn clone(&self) -> _ { FnTest9 }
    |                            not allowed in type signatures
    |                            help: replace with the correct return type: `FnTest9`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/typeck_type_placeholder_item.rs:122:41
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
+  --> $DIR/typeck_type_placeholder_item.rs:121:41
    |
 LL |         fn clone_from(&mut self, other: _) { *self = FnTest9; }
    |                                         ^ not allowed in type signatures
@@ -605,26 +605,26 @@ help: use type parameters instead
 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:205:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:204:14
    |
 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:207:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for associated types
+  --> $DIR/typeck_type_placeholder_item.rs:206:14
    |
 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:209:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:208:14
    |
 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:212:14
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/typeck_type_placeholder_item.rs:211:14
    |
 LL |     const D: _ = 42;
    |              ^
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.rs b/src/test/ui/typeck/typeck_type_placeholder_item.rs
index 8a52556ed34..55f5d44d46b 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item.rs
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.rs
@@ -8,67 +8,67 @@
 // inference by using the `_` type placeholder.
 
 fn test() -> _ { 5 }
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
 
 fn test2() -> (_, _) { (5, 5) }
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
 
 static TEST3: _ = "test";
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
 
 static TEST4: _ = 145;
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
 
 static TEST5: (_, _) = (1, 2);
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
 
 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 for functions
 
 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 for functions
 
 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 for functions
 
 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 for functions
 
 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 for functions
+//~^^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
 
 struct Test9;
 
 impl Test9 {
     fn test9(&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 for return types
 
     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 for functions
 }
 
 fn test11(x: &usize) -> &_ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
     &x
 }
 
 unsafe fn test12(x: *const usize) -> *const *const _ {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
     &x
 }
 
 impl Clone for Test9 {
     fn clone(&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 for return types
 
     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 for functions
 }
 
 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 for structs
     b: (_, _),
 }
 
@@ -76,95 +76,94 @@ pub fn main() {
     static A = 42;
     //~^ ERROR missing type for `static` item
     static B: _ = 42;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
     static C: Option<_> = Some(42);
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
-
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
     fn fn_test() -> _ { 5 }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
 
     fn fn_test2() -> (_, _) { (5, 5) }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
 
     static FN_TEST3: _ = "test";
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
 
     static FN_TEST4: _ = 145;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
 
     static FN_TEST5: (_, _) = (1, 2);
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for static variables
 
     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 for functions
 
     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 for functions
 
     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 for functions
+    //~^^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
 
     struct FnTest9;
 
     impl FnTest9 {
         fn fn_test9(&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 for return types
 
         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 for functions
     }
 
     impl Clone for FnTest9 {
         fn clone(&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 for return types
 
         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 for functions
     }
 
     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 for structs
         b: (_, _),
     }
 
     fn fn_test11(_: _) -> (_, _) { panic!() }
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
     //~| ERROR type annotations needed
 
     fn fn_test12(x: i32) -> (_, _) { (x, 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 for return types
 
     fn fn_test13(x: _) -> (i32, _) { (x, 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 for return types
 }
 
 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 for functions
     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 for functions
     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 for functions
     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 for functions
     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 for functions
     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 for functions
 }
 
 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 for structs
 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 for implementations
 
 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 for opaque types
     unimplemented!()
 }
 
@@ -172,19 +171,19 @@ struct BadStruct1<_, _>(_);
 //~^ ERROR expected identifier, found reserved identifier `_`
 //~| 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 for structs
 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 for structs
 
 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 for type aliases
 
 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 for opaque types
 fn foo() -> Y {
     Struct
 }
@@ -192,25 +191,25 @@ fn foo() -> Y {
 trait Qux {
     type A;
     type 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 for associated types
     const C: _;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
     const D: _ = 42;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
     // type E: _; // FIXME: make the parser propagate the existence of `B`
     type F: std::ops::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 for associated types
 }
 impl Qux for Struct {
     type 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 for associated types
     type 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 for associated types
     const C: _;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
     //~| ERROR associated constant in `impl` without body
     const D: _ = 42;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
 }
 
 fn map<T>(_: fn() -> Option<&'static T>) -> Option<T> {
@@ -218,9 +217,9 @@ fn map<T>(_: fn() -> Option<&'static T>) -> Option<T> {
 }
 
 fn value() -> Option<&'static _> {
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
     Option::<&'static u8>::None
 }
 
 const _: Option<_> = map(value);
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item_help.rs b/src/test/ui/typeck/typeck_type_placeholder_item_help.rs
index 0c890f88c60..3af5cf926ab 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item_help.rs
+++ b/src/test/ui/typeck/typeck_type_placeholder_item_help.rs
@@ -2,27 +2,27 @@
 // using the `_` type placeholder.
 
 fn test1() -> _ { Some(42) }
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for return types
 
 const TEST2: _ = 42u32;
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
 
 const TEST3: _ = Some(42);
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
 
 const TEST4: fn() -> _ = 42;
-//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures for functions
 
 trait Test5 {
     const TEST5: _ = 42;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
 }
 
 struct Test6;
 
 impl Test6 {
     const TEST6: _ = 13;
-    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures for constants
 }
 
 pub fn main() {
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item_help.stderr b/src/test/ui/typeck/typeck_type_placeholder_item_help.stderr
index 2b64df774b0..1b56b1033a8 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item_help.stderr
+++ b/src/test/ui/typeck/typeck_type_placeholder_item_help.stderr
@@ -1,4 +1,4 @@
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for return types
   --> $DIR/typeck_type_placeholder_item_help.rs:4:15
    |
 LL | fn test1() -> _ { Some(42) }
@@ -7,7 +7,7 @@ LL | fn test1() -> _ { Some(42) }
    |               not allowed in type signatures
    |               help: replace with the correct return type: `Option<i32>`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/typeck_type_placeholder_item_help.rs:7:14
    |
 LL | const TEST2: _ = 42u32;
@@ -16,7 +16,7 @@ LL | const TEST2: _ = 42u32;
    |              not allowed in type signatures
    |              help: replace with the correct type: `u32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/typeck_type_placeholder_item_help.rs:10:14
    |
 LL | const TEST3: _ = Some(42);
@@ -25,13 +25,13 @@ LL | const TEST3: _ = Some(42);
    |              not allowed in type signatures
    |              help: replace with the correct type: `Option<i32>`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for functions
   --> $DIR/typeck_type_placeholder_item_help.rs:13:22
    |
 LL | const TEST4: fn() -> _ = 42;
    |                      ^ not allowed in type signatures
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/typeck_type_placeholder_item_help.rs:17:18
    |
 LL |     const TEST5: _ = 42;
@@ -40,7 +40,7 @@ LL |     const TEST5: _ = 42;
    |                  not allowed in type signatures
    |                  help: replace with the correct type: `i32`
 
-error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/typeck_type_placeholder_item_help.rs:24:18
    |
 LL |     const TEST6: _ = 13;