Rollup merge of #97488 - vincenzopalazzo:macros/blanket_sugg, r=compiler-errors

Suggest blanket impl to the local traits

This PR will add additional suggestion regarding the blanket implementation when it is possible, by generation a new help message + suggestion.

Closes https://github.com/rust-lang/rust/issues/96076

Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>

2 files changed, 165 insertions, 0 deletions

diff --git a/src/test/ui/suggestions/suggest-blanket-impl-local-trait.rs b/src/test/ui/suggestions/suggest-blanket-impl-local-trait.rs
new file mode 100644
index 00000000000..7cf536f7966
--- /dev/null
+++ b/src/test/ui/suggestions/suggest-blanket-impl-local-trait.rs
@@ -0,0 +1,58 @@
+// Ensure that the compiler include the blanklet implementation suggestion
+// when inside a `impl` statment are used two local traits.
+//
+// edition:2021
+use std::fmt;
+
+trait LocalTraitOne { }
+
+trait LocalTraitTwo { }
+
+trait GenericTrait<T> {}
+
+impl LocalTraitTwo for LocalTraitOne {}
+//~^ ERROR trait objects must include the `dyn` keyword
+//~| HELP add `dyn` keyword before this trait
+//~| HELP alternatively use a blanket implementation to implement `LocalTraitTwo` for all types that also implement `LocalTraitOne`
+
+impl fmt::Display for LocalTraitOne {
+//~^ ERROR trait objects must include the `dyn` keyword
+//~| HELP add `dyn` keyword before this trait
+    fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        todo!();
+    }
+}
+
+impl fmt::Display for LocalTraitTwo + Send {
+//~^ ERROR trait objects must include the `dyn` keyword
+//~| HELP add `dyn` keyword before this trait
+    fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        todo!();
+    }
+}
+
+impl LocalTraitOne for fmt::Display {}
+//~^ ERROR trait objects must include the `dyn` keyword
+//~| HELP add `dyn` keyword before this trait
+//~| HELP alternatively use a blanket implementation to implement `LocalTraitOne` for all types that also implement `fmt::Display`
+
+
+impl LocalTraitOne for fmt::Display + Send {}
+//~^ ERROR trait objects must include the `dyn` keyword
+//~| HELP add `dyn` keyword before this trait
+//~| HELP alternatively use a blanket implementation to implement `LocalTraitOne` for all types that also implement `fmt::Display + Send`
+
+
+impl<E> GenericTrait<E> for LocalTraitOne {}
+//~^ ERROR trait objects must include the `dyn` keyword
+//~| HELP add `dyn` keyword before this trait
+//~| HELP alternatively use a blanket implementation to implement `GenericTrait<E>` for all types that also implement `LocalTraitOne`
+
+trait GenericTraitTwo<T> {}
+
+impl<T, E> GenericTraitTwo<E> for GenericTrait<T> {}
+//~^ ERROR trait objects must include the `dyn` keyword
+//~| HELP add `dyn` keyword before this trait
+//~| HELP alternatively use a blanket implementation to implement `GenericTraitTwo<E>` for all types that also implement `GenericTrait<T>`
+
+fn main() {}
diff --git a/src/test/ui/suggestions/suggest-blanket-impl-local-trait.stderr b/src/test/ui/suggestions/suggest-blanket-impl-local-trait.stderr
new file mode 100644
index 00000000000..d739a8272f1
--- /dev/null
+++ b/src/test/ui/suggestions/suggest-blanket-impl-local-trait.stderr
@@ -0,0 +1,107 @@
+error[E0782]: trait objects must include the `dyn` keyword
+  --> $DIR/suggest-blanket-impl-local-trait.rs:13:24
+   |
+LL | impl LocalTraitTwo for LocalTraitOne {}
+   |                        ^^^^^^^^^^^^^
+   |
+help: add `dyn` keyword before this trait
+   |
+LL - impl LocalTraitTwo for LocalTraitOne {}
+LL + impl LocalTraitTwo for dyn LocalTraitOne {}
+   |
+help: alternatively use a blanket implementation to implement `LocalTraitTwo` for all types that also implement `LocalTraitOne`
+   |
+LL | impl<T: LocalTraitOne> LocalTraitTwo for T {}
+   |     ++++++++++++++++++                   ~
+
+error[E0782]: trait objects must include the `dyn` keyword
+  --> $DIR/suggest-blanket-impl-local-trait.rs:18:23
+   |
+LL | impl fmt::Display for LocalTraitOne {
+   |                       ^^^^^^^^^^^^^
+   |
+help: add `dyn` keyword before this trait
+   |
+LL - impl fmt::Display for LocalTraitOne {
+LL + impl fmt::Display for dyn LocalTraitOne {
+   |
+
+error[E0782]: trait objects must include the `dyn` keyword
+  --> $DIR/suggest-blanket-impl-local-trait.rs:26:23
+   |
+LL | impl fmt::Display for LocalTraitTwo + Send {
+   |                       ^^^^^^^^^^^^^^^^^^^^
+   |
+help: add `dyn` keyword before this trait
+   |
+LL - impl fmt::Display for LocalTraitTwo + Send {
+LL + impl fmt::Display for dyn LocalTraitTwo + Send {
+   |
+
+error[E0782]: trait objects must include the `dyn` keyword
+  --> $DIR/suggest-blanket-impl-local-trait.rs:34:24
+   |
+LL | impl LocalTraitOne for fmt::Display {}
+   |                        ^^^^^^^^^^^^
+   |
+help: add `dyn` keyword before this trait
+   |
+LL - impl LocalTraitOne for fmt::Display {}
+LL + impl LocalTraitOne for dyn fmt::Display {}
+   |
+help: alternatively use a blanket implementation to implement `LocalTraitOne` for all types that also implement `fmt::Display`
+   |
+LL | impl<T: fmt::Display> LocalTraitOne for T {}
+   |     +++++++++++++++++                   ~
+
+error[E0782]: trait objects must include the `dyn` keyword
+  --> $DIR/suggest-blanket-impl-local-trait.rs:40:24
+   |
+LL | impl LocalTraitOne for fmt::Display + Send {}
+   |                        ^^^^^^^^^^^^^^^^^^^
+   |
+help: add `dyn` keyword before this trait
+   |
+LL - impl LocalTraitOne for fmt::Display + Send {}
+LL + impl LocalTraitOne for dyn fmt::Display + Send {}
+   |
+help: alternatively use a blanket implementation to implement `LocalTraitOne` for all types that also implement `fmt::Display + Send`
+   |
+LL | impl<T: fmt::Display + Send> LocalTraitOne for T {}
+   |     ++++++++++++++++++++++++                   ~
+
+error[E0782]: trait objects must include the `dyn` keyword
+  --> $DIR/suggest-blanket-impl-local-trait.rs:46:29
+   |
+LL | impl<E> GenericTrait<E> for LocalTraitOne {}
+   |                             ^^^^^^^^^^^^^
+   |
+help: add `dyn` keyword before this trait
+   |
+LL - impl<E> GenericTrait<E> for LocalTraitOne {}
+LL + impl<E> GenericTrait<E> for dyn LocalTraitOne {}
+   |
+help: alternatively use a blanket implementation to implement `GenericTrait<E>` for all types that also implement `LocalTraitOne`
+   |
+LL | impl<E, T: LocalTraitOne> GenericTrait<E> for T {}
+   |       ++++++++++++++++++                      ~
+
+error[E0782]: trait objects must include the `dyn` keyword
+  --> $DIR/suggest-blanket-impl-local-trait.rs:53:35
+   |
+LL | impl<T, E> GenericTraitTwo<E> for GenericTrait<T> {}
+   |                                   ^^^^^^^^^^^^^^^
+   |
+help: add `dyn` keyword before this trait
+   |
+LL - impl<T, E> GenericTraitTwo<E> for GenericTrait<T> {}
+LL + impl<T, E> GenericTraitTwo<E> for dyn GenericTrait<T> {}
+   |
+help: alternatively use a blanket implementation to implement `GenericTraitTwo<E>` for all types that also implement `GenericTrait<T>`
+   |
+LL | impl<T, E, U: GenericTrait<T>> GenericTraitTwo<E> for U {}
+   |          ++++++++++++++++++++                         ~
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0782`.