Rollup merge of #113453 - spastorino:new-rpitit-30, r=compiler-errors

Remove unused from_method from rustc_on_unimplemented

Fixes #113439

`on_unimplemented_note` was calling `item_name` for RPITITs and that produced ICEs. I've added a regression test for that but also have removed `from_method` symbol entirely because it wasn't even used and by doing that the `item_name` call was also removed.

r? ``@compiler-errors``

compiler/rustc_span/src/symbol.rs

@@ -759,7 +759,6 @@ symbols! {
         from_desugaring,
         from_fn,
         from_iter,
-        from_method,
         from_output,
         from_residual,
         from_size_align_unchecked,

compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs

@@ -41,7 +41,6 @@ pub trait TypeErrCtxtExt<'tcx> {
 static ALLOWED_FORMAT_SYMBOLS: &[Symbol] = &[
     kw::SelfUpper,
     sym::ItemContext,
-    sym::from_method,
     sym::from_desugaring,
     sym::direct,
     sym::cause,
@@ -172,23 +171,6 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             }
         }
 
-        if let ObligationCauseCode::ItemObligation(item)
-        | ObligationCauseCode::BindingObligation(item, _)
-        | ObligationCauseCode::ExprItemObligation(item, ..)
-        | ObligationCauseCode::ExprBindingObligation(item, ..) = *obligation.cause.code()
-        {
-            // FIXME: maybe also have some way of handling methods
-            // from other traits? That would require name resolution,
-            // which we might want to be some sort of hygienic.
-            //
-            // Currently I'm leaving it for what I need for `try`.
-            if self.tcx.trait_of_item(item) == Some(trait_ref.def_id) {
-                let method = self.tcx.item_name(item);
-                flags.push((sym::from_method, None));
-                flags.push((sym::from_method, Some(method.to_string())));
-            }
-        }
-
         if let Some(k) = obligation.cause.span.desugaring_kind() {
             flags.push((sym::from_desugaring, None));
             flags.push((sym::from_desugaring, Some(format!("{:?}", k))));
@@ -672,7 +654,7 @@ impl<'tcx> OnUnimplementedFormatString {
                             None => {
                                 if let Some(val) = options.get(&s) {
                                     val
-                                } else if s == sym::from_desugaring || s == sym::from_method {
+                                } else if s == sym::from_desugaring {
                                     // don't break messages using these two arguments incorrectly
                                     &empty_string
                                 } else if s == sym::ItemContext {

tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.current.stderr

@@ -0,0 +1,16 @@
+error[E0277]: the trait bound `impl Foo<u8>: Foo<char>` is not satisfied
+  --> $DIR/return-dont-satisfy-bounds.rs:13:34
+   |
+LL |     fn foo<F2: Foo<u8>>(self) -> impl Foo<u8> {
+   |                                  ^^^^^^^^^^^^ the trait `Foo<char>` is not implemented for `impl Foo<u8>`
+   |
+   = help: the trait `Foo<char>` is implemented for `Bar`
+note: required by a bound in `Foo::foo::{opaque#0}`
+  --> $DIR/return-dont-satisfy-bounds.rs:7:30
+   |
+LL |     fn foo<F2>(self) -> impl Foo<T>;
+   |                              ^^^^^^ required by this bound in `Foo::foo::{opaque#0}`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.

tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.next.stderr

@@ -0,0 +1,16 @@
+error[E0277]: the trait bound `impl Foo<u8>: Foo<char>` is not satisfied
+  --> $DIR/return-dont-satisfy-bounds.rs:13:34
+   |
+LL |     fn foo<F2: Foo<u8>>(self) -> impl Foo<u8> {
+   |                                  ^^^^^^^^^^^^ the trait `Foo<char>` is not implemented for `impl Foo<u8>`
+   |
+   = help: the trait `Foo<char>` is implemented for `Bar`
+note: required by a bound in `Foo::{opaque#0}`
+  --> $DIR/return-dont-satisfy-bounds.rs:7:30
+   |
+LL |     fn foo<F2>(self) -> impl Foo<T>;
+   |                              ^^^^^^ required by this bound in `Foo::{opaque#0}`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.

tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.rs

@@ -0,0 +1,19 @@
+// [next] compile-flags: -Zlower-impl-trait-in-trait-to-assoc-ty
+// revisions: current next
+
+#![feature(return_position_impl_trait_in_trait)]
+
+trait Foo<T> {
+    fn foo<F2>(self) -> impl Foo<T>;
+}
+
+struct Bar;
+
+impl Foo<char> for Bar {
+    fn foo<F2: Foo<u8>>(self) -> impl Foo<u8> {
+        //~^ ERROR: the trait bound `impl Foo<u8>: Foo<char>` is not satisfied [E0277]
+        self
+    }
+}
+
+fn main() {}