Rollup merge of #143234 - GuillaumeGomez:ice-143128, r=oli-obk

Replace `ItemCtxt::report_placeholder_type_error` match with a call to `TyCtxt::def_descr`

Fixes #143128.

We could likely use `tcx.def_descr` in more places (and therefore remove more `descr` methods). If it's something that we want to do, I can send a follow-up.

r? `@oli-obk`

Author: matthiaskrgr

compiler/rustc_hir/src/hir.rs

@@ -3141,15 +3141,6 @@ pub enum TraitItemKind<'hir> {
     /// type.
     Type(GenericBounds<'hir>, Option<&'hir Ty<'hir>>),
 }
-impl TraitItemKind<'_> {
-    pub fn descr(&self) -> &'static str {
-        match self {
-            TraitItemKind::Const(..) => "associated constant",
-            TraitItemKind::Fn(..) => "function",
-            TraitItemKind::Type(..) => "associated type",
-        }
-    }
-}
 
 // The bodies for items are stored "out of line", in a separate
 // hashmap in the `Crate`. Here we just record the hir-id of the item
@@ -3211,15 +3202,6 @@ pub enum ImplItemKind<'hir> {
     /// An associated type.
     Type(&'hir Ty<'hir>),
 }
-impl ImplItemKind<'_> {
-    pub fn descr(&self) -> &'static str {
-        match self {
-            ImplItemKind::Const(..) => "associated constant",
-            ImplItemKind::Fn(..) => "function",
-            ImplItemKind::Type(..) => "associated type",
-        }
-    }
-}
 
 /// A constraint on an associated item.
 ///
@@ -4545,16 +4527,6 @@ pub enum ForeignItemKind<'hir> {
     Type,
 }
 
-impl ForeignItemKind<'_> {
-    pub fn descr(&self) -> &'static str {
-        match self {
-            ForeignItemKind::Fn(..) => "function",
-            ForeignItemKind::Static(..) => "static variable",
-            ForeignItemKind::Type => "type",
-        }
-    }
-}
-
 /// A variable captured by a closure.
 #[derive(Debug, Copy, Clone, HashStable_Generic)]
 pub struct Upvar {

compiler/rustc_hir_analysis/src/collect.rs

@@ -277,17 +277,7 @@ impl<'tcx> ItemCtxt<'tcx> {
             }
             _ => self.item_def_id,
         };
-        // FIXME: just invoke `tcx.def_descr` instead of going through the HIR
-        // Can also remove most `descr` methods then.
-        let kind = match self.tcx.hir_node_by_def_id(kind_id) {
-            Node::Item(it) => it.kind.descr(),
-            Node::ImplItem(it) => it.kind.descr(),
-            Node::TraitItem(it) => it.kind.descr(),
-            Node::ForeignItem(it) => it.kind.descr(),
-            Node::OpaqueTy(_) => "opaque type",
-            Node::Synthetic => self.tcx.def_descr(kind_id.into()),
-            node => todo!("{node:#?}"),
-        };
+        let kind = self.tcx.def_descr(kind_id.into());
         let mut diag = placeholder_type_error_diag(
             self,
             generics,

tests/rustdoc-ui/invalid_infered_static_and_const.stderr

@@ -1,10 +1,10 @@
-error[E0121]: the placeholder `_` is not allowed within types on item signatures for constant items
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
   --> $DIR/invalid_infered_static_and_const.rs:1:24
    |
 LL | const FOO: dyn Fn() -> _ = "";
    |                        ^ not allowed in type signatures
 
-error[E0121]: the placeholder `_` is not allowed within types on item signatures for static items
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for statics
   --> $DIR/invalid_infered_static_and_const.rs:2:25
    |
 LL | static BOO: dyn Fn() -> _ = "";

tests/ui/closures/missing-body.rs

@@ -0,0 +1,7 @@
+// Checks that the compiler complains about the missing closure body and does not
+// crash.
+// This is a regression test for <https://github.com/rust-lang/rust/issues/143128>.
+
+fn main() { |b: [str; _]| {}; }
+//~^ ERROR the placeholder `_` is not allowed within types on item signatures for closures
+//~| ERROR the size for values of type `str` cannot be known at compilation time

tests/ui/closures/missing-body.stderr

@@ -0,0 +1,19 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for closures
+  --> $DIR/missing-body.rs:5:23
+   |
+LL | fn main() { |b: [str; _]| {}; }
+   |                       ^ not allowed in type signatures
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/missing-body.rs:5:17
+   |
+LL | fn main() { |b: [str; _]| {}; }
+   |                 ^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+   = note: slice and array elements must have `Sized` type
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0121, E0277.
+For more information about an error, try `rustc --explain E0121`.

tests/ui/did_you_mean/bad-assoc-ty.edition2015.stderr

@@ -302,7 +302,7 @@ error[E0121]: the placeholder `_` is not allowed within types on item signatures
 LL | trait P<F> where F: Fn() -> _ {
    |                             ^ not allowed in type signatures
 
-error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated functions
   --> $DIR/bad-assoc-ty.rs:88:38
    |
 LL |     fn foo<F>(_: F) where F: Fn() -> _ {}

tests/ui/did_you_mean/bad-assoc-ty.edition2021.stderr

@@ -284,7 +284,7 @@ error[E0121]: the placeholder `_` is not allowed within types on item signatures
 LL | trait P<F> where F: Fn() -> _ {
    |                             ^ not allowed in type signatures
 
-error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated functions
   --> $DIR/bad-assoc-ty.rs:88:38
    |
 LL |     fn foo<F>(_: F) where F: Fn() -> _ {}

tests/ui/did_you_mean/bad-assoc-ty.rs

@@ -86,7 +86,7 @@ trait P<F> where F: Fn() -> _ {
 
 trait Q {
     fn foo<F>(_: F) where F: Fn() -> _ {}
-    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+    //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated functions
 }
 
 fn main() {}

tests/ui/did_you_mean/replace-impl-infer-ty-from-trait.fixed

@@ -7,7 +7,7 @@ trait Foo<T>: Sized {
 
 impl Foo<usize> for () {
     fn bar(i: i32, t: usize, s: &()) -> (usize, i32) {
-        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated functions
         //~| ERROR type annotations needed
         (1, 2)
     }

tests/ui/did_you_mean/replace-impl-infer-ty-from-trait.rs

@@ -7,7 +7,7 @@ trait Foo<T>: Sized {
 
 impl Foo<usize> for () {
     fn bar(i: _, t: _, s: _) -> _ {
-        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for functions
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated functions
         //~| ERROR type annotations needed
         (1, 2)
     }