Fix useless_attribute FP on deprecated_in_future

clippy_lints/src/attrs/useless_attribute.rs

@@ -30,6 +30,7 @@ pub(super) fn check(cx: &EarlyContext<'_>, item: &Item, attrs: &[Attribute]) {
                                 sym::ambiguous_glob_reexports
                                     | sym::dead_code
                                     | sym::deprecated
+                                    | sym::deprecated_in_future
                                     | sym::hidden_glob_reexports
                                     | sym::unreachable_pub
                                     | sym::unused

clippy_utils/src/sym.rs

@@ -125,6 +125,7 @@ generate! {
     cycle,
     cyclomatic_complexity,
     de,
+    deprecated_in_future,
     diagnostics,
     disallowed_types,
     drain,

tests/ui/useless_attribute.fixed

@@ -158,3 +158,13 @@ pub mod redundant_imports_issue {
 
     empty!();
 }
+
+pub mod issue15636 {
+    pub mod f {
+        #[deprecated(since = "TBD")]
+        pub mod deprec {}
+    }
+
+    #[allow(deprecated_in_future)]
+    pub use f::deprec;
+}

tests/ui/useless_attribute.rs

@@ -158,3 +158,13 @@ pub mod redundant_imports_issue {
 
     empty!();
 }
+
+pub mod issue15636 {
+    pub mod f {
+        #[deprecated(since = "TBD")]
+        pub mod deprec {}
+    }
+
+    #[allow(deprecated_in_future)]
+    pub use f::deprec;
+}