Move `#[do_not_recommend]` to the `#[diagnostic]` namespace

This commit moves the `#[do_not_recommend]` attribute to the
`#[diagnostic]` namespace. It still requires
`#![feature(do_not_recommend)]` to work.

9 files changed, 148 insertions, 3 deletions

diff --git a/tests/ui/diagnostic_namespace/do_not_recommend/as_expression.rs b/tests/ui/diagnostic_namespace/do_not_recommend/as_expression.rs
index 9cdc193d386..5fd5cc54400 100644
--- a/tests/ui/diagnostic_namespace/do_not_recommend/as_expression.rs
+++ b/tests/ui/diagnostic_namespace/do_not_recommend/as_expression.rs
@@ -26,7 +26,7 @@ impl<T> Expression for Bound<T> {
     type SqlType = T;
 }
 
-#[do_not_recommend]
+#[diagnostic::do_not_recommend]
 impl<T, ST> AsExpression<ST> for T
 where
     T: Expression<SqlType = ST>,
diff --git a/tests/ui/diagnostic_namespace/do_not_recommend/feature-gate-do_not_recommend.rs b/tests/ui/diagnostic_namespace/do_not_recommend/feature-gate-do_not_recommend.rs
new file mode 100644
index 00000000000..5a26d28188c
--- /dev/null
+++ b/tests/ui/diagnostic_namespace/do_not_recommend/feature-gate-do_not_recommend.rs
@@ -0,0 +1,17 @@
+#![feature(do_not_recommend)]
+
+pub trait Foo {}
+
+impl Foo for i32 {}
+
+pub trait Bar {}
+
+#[diagnostic::do_not_recommend]
+impl<T: Foo> Bar for T {}
+
+fn stuff<T: Bar>(_: T) {}
+
+fn main() {
+    stuff(1u8);
+    //~^ the trait bound `u8: Bar` is not satisfied
+}
diff --git a/tests/ui/diagnostic_namespace/do_not_recommend/feature-gate-do_not_recommend.stderr b/tests/ui/diagnostic_namespace/do_not_recommend/feature-gate-do_not_recommend.stderr
new file mode 100644
index 00000000000..3951231fa2e
--- /dev/null
+++ b/tests/ui/diagnostic_namespace/do_not_recommend/feature-gate-do_not_recommend.stderr
@@ -0,0 +1,15 @@
+error[E0277]: the trait bound `u8: Bar` is not satisfied
+  --> $DIR/feature-gate-do_not_recommend.rs:15:11
+   |
+LL |     stuff(1u8);
+   |           ^^^ the trait `Bar` is not implemented for `u8`
+   |
+note: required by a bound in `stuff`
+  --> $DIR/feature-gate-do_not_recommend.rs:12:13
+   |
+LL | fn stuff<T: Bar>(_: T) {}
+   |             ^^^ required by this bound in `stuff`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/diagnostic_namespace/do_not_recommend/incorrect-locations.rs b/tests/ui/diagnostic_namespace/do_not_recommend/incorrect-locations.rs
new file mode 100644
index 00000000000..400ef83873e
--- /dev/null
+++ b/tests/ui/diagnostic_namespace/do_not_recommend/incorrect-locations.rs
@@ -0,0 +1,39 @@
+//@ check-pass
+#![feature(do_not_recommend)]
+
+#[diagnostic::do_not_recommend]
+//~^WARN `#[diagnostic::do_not_recommend]` can only be placed
+const CONST: () = ();
+
+#[diagnostic::do_not_recommend]
+//~^WARN `#[diagnostic::do_not_recommend]` can only be placed
+static STATIC: () = ();
+
+#[diagnostic::do_not_recommend]
+//~^WARN `#[diagnostic::do_not_recommend]` can only be placed
+type Type = ();
+
+#[diagnostic::do_not_recommend]
+//~^WARN `#[diagnostic::do_not_recommend]` can only be placed
+enum Enum {}
+
+#[diagnostic::do_not_recommend]
+//~^WARN `#[diagnostic::do_not_recommend]` can only be placed
+extern "C" {}
+
+#[diagnostic::do_not_recommend]
+//~^WARN `#[diagnostic::do_not_recommend]` can only be placed
+fn fun() {}
+
+#[diagnostic::do_not_recommend]
+//~^WARN `#[diagnostic::do_not_recommend]` can only be placed
+struct Struct {}
+
+#[diagnostic::do_not_recommend]
+//~^WARN `#[diagnostic::do_not_recommend]` can only be placed
+trait Trait {}
+
+#[diagnostic::do_not_recommend]
+impl Trait for i32 {}
+
+fn main() {}
diff --git a/tests/ui/diagnostic_namespace/do_not_recommend/incorrect-locations.stderr b/tests/ui/diagnostic_namespace/do_not_recommend/incorrect-locations.stderr
new file mode 100644
index 00000000000..c83fd46db58
--- /dev/null
+++ b/tests/ui/diagnostic_namespace/do_not_recommend/incorrect-locations.stderr
@@ -0,0 +1,52 @@
+warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
+  --> $DIR/incorrect-locations.rs:4:1
+   |
+LL | #[diagnostic::do_not_recommend]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default
+
+warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
+  --> $DIR/incorrect-locations.rs:8:1
+   |
+LL | #[diagnostic::do_not_recommend]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
+  --> $DIR/incorrect-locations.rs:12:1
+   |
+LL | #[diagnostic::do_not_recommend]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
+  --> $DIR/incorrect-locations.rs:16:1
+   |
+LL | #[diagnostic::do_not_recommend]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
+  --> $DIR/incorrect-locations.rs:20:1
+   |
+LL | #[diagnostic::do_not_recommend]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
+  --> $DIR/incorrect-locations.rs:24:1
+   |
+LL | #[diagnostic::do_not_recommend]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
+  --> $DIR/incorrect-locations.rs:28:1
+   |
+LL | #[diagnostic::do_not_recommend]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
+  --> $DIR/incorrect-locations.rs:32:1
+   |
+LL | #[diagnostic::do_not_recommend]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: 8 warnings emitted
+
diff --git a/tests/ui/diagnostic_namespace/do_not_recommend/simple.rs b/tests/ui/diagnostic_namespace/do_not_recommend/simple.rs
index 6fb15b90138..780649b009c 100644
--- a/tests/ui/diagnostic_namespace/do_not_recommend/simple.rs
+++ b/tests/ui/diagnostic_namespace/do_not_recommend/simple.rs
@@ -6,7 +6,7 @@
 
 trait Foo {}
 
-#[do_not_recommend]
+#[diagnostic::do_not_recommend]
 impl<T> Foo for T where T: Send {}
 
 fn needs_foo<T: Foo>() {}
diff --git a/tests/ui/diagnostic_namespace/do_not_recommend/stacked.rs b/tests/ui/diagnostic_namespace/do_not_recommend/stacked.rs
index 695660d3596..fc355bdc4e2 100644
--- a/tests/ui/diagnostic_namespace/do_not_recommend/stacked.rs
+++ b/tests/ui/diagnostic_namespace/do_not_recommend/stacked.rs
@@ -8,7 +8,7 @@ trait Root {}
 trait DontRecommend {}
 trait Other {}
 
-#[do_not_recommend]
+#[diagnostic::do_not_recommend]
 impl<T> Root for T where T: DontRecommend {}
 
 impl<T> DontRecommend for T where T: Other {}
diff --git a/tests/ui/diagnostic_namespace/do_not_recommend/unstable-feature.rs b/tests/ui/diagnostic_namespace/do_not_recommend/unstable-feature.rs
new file mode 100644
index 00000000000..ccc687aa5b3
--- /dev/null
+++ b/tests/ui/diagnostic_namespace/do_not_recommend/unstable-feature.rs
@@ -0,0 +1,8 @@
+#![deny(unknown_or_malformed_diagnostic_attributes)]
+trait Foo {}
+
+#[diagnostic::do_not_recommend]
+//~^ ERROR unknown diagnostic attribute [unknown_or_malformed_diagnostic_attributes]
+impl Foo for i32 {}
+
+fn main() {}
diff --git a/tests/ui/diagnostic_namespace/do_not_recommend/unstable-feature.stderr b/tests/ui/diagnostic_namespace/do_not_recommend/unstable-feature.stderr
new file mode 100644
index 00000000000..d8332229d4f
--- /dev/null
+++ b/tests/ui/diagnostic_namespace/do_not_recommend/unstable-feature.stderr
@@ -0,0 +1,14 @@
+error: unknown diagnostic attribute
+  --> $DIR/unstable-feature.rs:4:15
+   |
+LL | #[diagnostic::do_not_recommend]
+   |               ^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/unstable-feature.rs:1:9
+   |
+LL | #![deny(unknown_or_malformed_diagnostic_attributes)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+