Rollup merge of #89090 - cjgillot:bare-dyn, r=jackh726

Lint bare traits in AstConv.

Removing the lint from lowering allows to:
- make lowering querification easier;
- have the lint implementation in only one place.

r? `@estebank`

7 files changed, 37 insertions, 69 deletions

diff --git a/src/test/ui/parser/issues/issue-68890-2.rs b/src/test/ui/parser/issues/issue-68890-2.rs
index 0a6e26acfc7..29c12352146 100644
--- a/src/test/ui/parser/issues/issue-68890-2.rs
+++ b/src/test/ui/parser/issues/issue-68890-2.rs
@@ -3,5 +3,3 @@ fn main() {}
 type X<'a> = (?'a) +;
 //~^ ERROR `?` may only modify trait bounds, not lifetime bounds
 //~| ERROR at least one trait is required for an object type
-//~| WARN trait objects without an explicit `dyn` are deprecated
-//~| WARN this is accepted in the current edition
diff --git a/src/test/ui/parser/issues/issue-68890-2.stderr b/src/test/ui/parser/issues/issue-68890-2.stderr
index 1a64b9a017d..d9fb7beebdb 100644
--- a/src/test/ui/parser/issues/issue-68890-2.stderr
+++ b/src/test/ui/parser/issues/issue-68890-2.stderr
@@ -4,22 +4,12 @@ error: `?` may only modify trait bounds, not lifetime bounds
 LL | type X<'a> = (?'a) +;
    |               ^
 
-warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/issue-68890-2.rs:3:14
-   |
-LL | type X<'a> = (?'a) +;
-   |              ^^^^^^^ help: use `dyn`: `dyn (?'a) +`
-   |
-   = note: `#[warn(bare_trait_objects)]` on by default
-   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
-   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
-
 error[E0224]: at least one trait is required for an object type
   --> $DIR/issue-68890-2.rs:3:14
    |
 LL | type X<'a> = (?'a) +;
    |              ^^^^^^^
 
-error: aborting due to 2 previous errors; 1 warning emitted
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0224`.
diff --git a/src/test/ui/parser/issues/issue-73568-lifetime-after-mut.rs b/src/test/ui/parser/issues/issue-73568-lifetime-after-mut.rs
index e68ee747cfd..5f731f8db77 100644
--- a/src/test/ui/parser/issues/issue-73568-lifetime-after-mut.rs
+++ b/src/test/ui/parser/issues/issue-73568-lifetime-after-mut.rs
@@ -13,11 +13,7 @@ mac!('a);
 // avoid false positives
 fn y<'a>(y: &mut 'a + Send) {
     //~^ ERROR expected a path on the left-hand side of `+`, not `&mut 'a`
-    //~| WARNING trait objects without an explicit `dyn` are deprecated
-    //~| WARN this is accepted in the current edition
     //~| ERROR at least one trait is required for an object type
     let z = y as &mut 'a + Send;
     //~^ ERROR expected value, found trait `Send`
-    //~| WARNING trait objects without an explicit `dyn` are deprecated
-    //~| WARN this is accepted in the current edition
 }
diff --git a/src/test/ui/parser/issues/issue-73568-lifetime-after-mut.stderr b/src/test/ui/parser/issues/issue-73568-lifetime-after-mut.stderr
index 48c2b2a19d4..799bc16bd6a 100644
--- a/src/test/ui/parser/issues/issue-73568-lifetime-after-mut.stderr
+++ b/src/test/ui/parser/issues/issue-73568-lifetime-after-mut.stderr
@@ -22,37 +22,18 @@ LL | mac!('a);
    = note: this error originates in the macro `mac` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0423]: expected value, found trait `Send`
-  --> $DIR/issue-73568-lifetime-after-mut.rs:19:28
+  --> $DIR/issue-73568-lifetime-after-mut.rs:17:28
    |
 LL |     let z = y as &mut 'a + Send;
    |                            ^^^^ not a value
 
-warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/issue-73568-lifetime-after-mut.rs:14:18
-   |
-LL | fn y<'a>(y: &mut 'a + Send) {
-   |                  ^^ help: use `dyn`: `dyn 'a`
-   |
-   = note: `#[warn(bare_trait_objects)]` on by default
-   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
-   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
-
-warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/issue-73568-lifetime-after-mut.rs:19:23
-   |
-LL |     let z = y as &mut 'a + Send;
-   |                       ^^ help: use `dyn`: `dyn 'a`
-   |
-   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
-   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
-
 error[E0224]: at least one trait is required for an object type
   --> $DIR/issue-73568-lifetime-after-mut.rs:14:18
    |
 LL | fn y<'a>(y: &mut 'a + Send) {
    |                  ^^
 
-error: aborting due to 5 previous errors; 2 warnings emitted
+error: aborting due to 5 previous errors
 
 Some errors have detailed explanations: E0178, E0224, E0423.
 For more information about an error, try `rustc --explain E0178`.
diff --git a/src/test/ui/parser/macro/trait-object-macro-matcher.rs b/src/test/ui/parser/macro/trait-object-macro-matcher.rs
index 663739f235a..560195977d0 100644
--- a/src/test/ui/parser/macro/trait-object-macro-matcher.rs
+++ b/src/test/ui/parser/macro/trait-object-macro-matcher.rs
@@ -11,6 +11,4 @@ fn main() {
     m!('static);
     //~^ ERROR lifetime in trait object type must be followed by `+`
     //~| ERROR at least one trait is required for an object type
-    //~| WARN trait objects without an explicit `dyn` are deprecated
-    //~| WARN this is accepted in the current edition
 }
diff --git a/src/test/ui/parser/macro/trait-object-macro-matcher.stderr b/src/test/ui/parser/macro/trait-object-macro-matcher.stderr
index 876bfd389cb..40082564bad 100644
--- a/src/test/ui/parser/macro/trait-object-macro-matcher.stderr
+++ b/src/test/ui/parser/macro/trait-object-macro-matcher.stderr
@@ -4,22 +4,12 @@ error: lifetime in trait object type must be followed by `+`
 LL |     m!('static);
    |        ^^^^^^^
 
-warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/trait-object-macro-matcher.rs:11:8
-   |
-LL |     m!('static);
-   |        ^^^^^^^ help: use `dyn`: `dyn 'static`
-   |
-   = note: `#[warn(bare_trait_objects)]` on by default
-   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
-   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
-
 error[E0224]: at least one trait is required for an object type
   --> $DIR/trait-object-macro-matcher.rs:11:8
    |
 LL |     m!('static);
    |        ^^^^^^^
 
-error: aborting due to 2 previous errors; 1 warning emitted
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0224`.
diff --git a/src/test/ui/parser/trait-object-trait-parens.stderr b/src/test/ui/parser/trait-object-trait-parens.stderr
index 657288c70f3..a852337b6fe 100644
--- a/src/test/ui/parser/trait-object-trait-parens.stderr
+++ b/src/test/ui/parser/trait-object-trait-parens.stderr
@@ -20,29 +20,16 @@ warning: trait objects without an explicit `dyn` are deprecated
   --> $DIR/trait-object-trait-parens.rs:8:16
    |
 LL |     let _: Box<(Obj) + (?Sized) + (for<'a> Trait<'a>)>;
-   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn (Obj) + (?Sized) + (for<'a> Trait<'a>)`
+   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(bare_trait_objects)]` on by default
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
-
-warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/trait-object-trait-parens.rs:13:16
-   |
-LL |     let _: Box<?Sized + (for<'a> Trait<'a>) + (Obj)>;
-   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn ?Sized + (for<'a> Trait<'a>) + (Obj)`
+help: use `dyn`
    |
-   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
-   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
-
-warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/trait-object-trait-parens.rs:18:16
-   |
-LL |     let _: Box<for<'a> Trait<'a> + (Obj) + (?Sized)>;
-   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn for<'a> Trait<'a> + (Obj) + (?Sized)`
-   |
-   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
-   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
+LL -     let _: Box<(Obj) + (?Sized) + (for<'a> Trait<'a>)>;
+LL +     let _: Box<dyn (Obj) + (?Sized) + (for<'a> Trait<'a>)>;
+   | 
 
 error[E0225]: only auto traits can be used as additional traits in a trait object
   --> $DIR/trait-object-trait-parens.rs:8:35
@@ -55,6 +42,20 @@ LL |     let _: Box<(Obj) + (?Sized) + (for<'a> Trait<'a>)>;
    = help: consider creating a new trait with all of these as supertraits and using that trait here instead: `trait NewTrait: Obj + for<'a> Trait<'a> {}`
    = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>
 
+warning: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/trait-object-trait-parens.rs:13:16
+   |
+LL |     let _: Box<?Sized + (for<'a> Trait<'a>) + (Obj)>;
+   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
+help: use `dyn`
+   |
+LL -     let _: Box<?Sized + (for<'a> Trait<'a>) + (Obj)>;
+LL +     let _: Box<dyn ?Sized + (for<'a> Trait<'a>) + (Obj)>;
+   | 
+
 error[E0225]: only auto traits can be used as additional traits in a trait object
   --> $DIR/trait-object-trait-parens.rs:13:47
    |
@@ -66,6 +67,20 @@ LL |     let _: Box<?Sized + (for<'a> Trait<'a>) + (Obj)>;
    = help: consider creating a new trait with all of these as supertraits and using that trait here instead: `trait NewTrait: for<'a> Trait<'a> + Obj {}`
    = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>
 
+warning: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/trait-object-trait-parens.rs:18:16
+   |
+LL |     let _: Box<for<'a> Trait<'a> + (Obj) + (?Sized)>;
+   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
+help: use `dyn`
+   |
+LL -     let _: Box<for<'a> Trait<'a> + (Obj) + (?Sized)>;
+LL +     let _: Box<dyn for<'a> Trait<'a> + (Obj) + (?Sized)>;
+   | 
+
 error[E0225]: only auto traits can be used as additional traits in a trait object
   --> $DIR/trait-object-trait-parens.rs:18:36
    |