Warn on unused doc(hidden) on trait impl items

diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index b297012f19f2f17475a6e2807ef82cd825cce38e..2b0fa57cba8b1f7d2695a7664e76ae217cca1038 100644 (file)
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -4,7 +4,8 @@
 //! conflicts between multiple such attributes attached to the same
 //! item.
 
-use rustc_ast::{ast, AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem};
+use rustc_ast::tokenstream::DelimSpan;
+use rustc_ast::{ast, AttrStyle, Attribute, Lit, LitKind, MacArgs, MetaItemKind, NestedMetaItem};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{pluralize, struct_span_err, Applicability, MultiSpan};
 use rustc_feature::{AttributeDuplicates, AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
@@ -810,6 +811,68 @@ fn check_doc_inline(
         }
     }
 
+    /// Checks `#[doc(hidden)]` attributes. Returns `true` if valid.
+    fn check_doc_hidden(
+        &self,
+        attr: &Attribute,
+        meta_index: usize,
+        meta: &NestedMetaItem,
+        hir_id: HirId,
+        target: Target,
+    ) -> bool {
+        if let Target::AssocConst
+        | Target::AssocTy
+        | Target::Method(MethodKind::Trait { body: true }) = target
+        {
+            let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
+            let containing_item = self.tcx.hir().expect_item(parent_hir_id);
+
+            if Target::from_item(containing_item) == Target::Impl {
+                let meta_items = attr.meta_item_list().unwrap();
+
+                let (span, replacement_span) = if meta_items.len() == 1 {
+                    (attr.span, attr.span)
+                } else {
+                    let meta_span = meta.span();
+                    (
+                        meta_span,
+                        meta_span.until(match meta_items.get(meta_index + 1) {
+                            Some(next_item) => next_item.span(),
+                            None => match attr.get_normal_item().args {
+                                MacArgs::Delimited(DelimSpan { close, .. }, ..) => close,
+                                _ => unreachable!(),
+                            },
+                        }),
+                    )
+                };
+
+                // FIXME: #[doc(hidden)] was previously erroneously allowed on trait impl items,
+                // so for backward compatibility only emit a warning and do not mark it as invalid.
+                self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, span, |lint| {
+                    lint.build("`#[doc(hidden)]` is ignored on trait impl items")
+                        .warn(
+                            "this was previously accepted by the compiler but is \
+                             being phased out; it will become a hard error in \
+                             a future release!",
+                        )
+                        .note(
+                            "whether the impl item is `doc(hidden)` or not \
+                             entirely depends on the corresponding trait item",
+                        )
+                        .span_suggestion(
+                            replacement_span,
+                            "remove this attribute",
+                            String::new(),
+                            Applicability::MachineApplicable,
+                        )
+                        .emit();
+                });
+            }
+        }
+
+        true
+    }
+
     /// Checks that an attribute is *not* used at the crate level. Returns `true` if valid.
     fn check_attr_not_crate_level(
         &self,
@@ -928,7 +991,7 @@ fn check_doc_attrs(
         let mut is_valid = true;
 
         if let Some(mi) = attr.meta() && let Some(list) = mi.meta_item_list() {
-            for meta in list {
+            for (meta_index, meta) in list.into_iter().enumerate() {
                 if let Some(i_meta) = meta.meta_item() {
                     match i_meta.name_or_empty() {
                         sym::alias
@@ -969,6 +1032,15 @@ fn check_doc_attrs(
                             is_valid = false;
                         }
 
+                        sym::hidden if !self.check_doc_hidden(attr,
+                            meta_index,
+                            meta,
+                            hir_id,
+                            target,
+                            ) => {
+                            is_valid = false;
+                        }
+
                         // no_default_passes: deprecated
                         // passes: deprecated
                         // plugins: removed, but rustdoc warns about it itself

diff --git a/library/alloc/src/collections/vec_deque/iter.rs b/library/alloc/src/collections/vec_deque/iter.rs
index e8290809276fbf031ad414615f4e1814edbff0f5..19198ab3aa1b53f562628ea16a2ffbcd3062667d 100644 (file)
--- a/library/alloc/src/collections/vec_deque/iter.rs
+++ b/library/alloc/src/collections/vec_deque/iter.rs
@@ -122,7 +122,6 @@ fn last(mut self) -> Option<&'a T> {
     }
 
     #[inline]
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         // Safety: The TrustedRandomAccess contract requires that callers only pass an index
         // that is in bounds.

diff --git a/library/alloc/src/collections/vec_deque/iter_mut.rs b/library/alloc/src/collections/vec_deque/iter_mut.rs
index ee2df0d5160127a26676b89f5ea04c39ff736136..b78c0d5e1b3cfdbeb68dfd134e8c3aa02c144b66 100644 (file)
--- a/library/alloc/src/collections/vec_deque/iter_mut.rs
+++ b/library/alloc/src/collections/vec_deque/iter_mut.rs
@@ -100,7 +100,6 @@ fn last(mut self) -> Option<&'a mut T> {
     }
 
     #[inline]
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         // Safety: The TrustedRandomAccess contract requires that callers only pass an index
         // that is in bounds.

diff --git a/library/alloc/src/vec/into_iter.rs b/library/alloc/src/vec/into_iter.rs
index 8134eea570ad722e347379b41973f4880e1b7abf..a7df6f59b59894270fffd5fd005c5e06024365eb 100644 (file)
--- a/library/alloc/src/vec/into_iter.rs
+++ b/library/alloc/src/vec/into_iter.rs
@@ -202,7 +202,6 @@ fn count(self) -> usize {
         self.len()
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> Self::Item
     where
         Self: TrustedRandomAccessNoCoerce,

diff --git a/library/core/src/convert/num.rs b/library/core/src/convert/num.rs
index 2b6ea90bf043019dd9f177fcb313716e8ab42d88..4fa5d129bc6af6ccfa6853c8cc16cf76ea1839dc 100644 (file)
--- a/library/core/src/convert/num.rs
+++ b/library/core/src/convert/num.rs
@@ -25,7 +25,6 @@ impl private::Sealed for $Float {}
         $(
             #[unstable(feature = "convert_float_to_int", issue = "67057")]
             impl FloatToInt<$Int> for $Float {
-                #[doc(hidden)]
                 #[inline]
                 unsafe fn to_int_unchecked(self) -> $Int {
                     // SAFETY: the safety contract must be upheld by the caller.

diff --git a/library/core/src/iter/adapters/cloned.rs b/library/core/src/iter/adapters/cloned.rs
index 71a5a4ea831ffe6a12914a4eee5eebf34a33f3a4..aba24a79dcf7920595ed1f1a70a73f4540011853 100644 (file)
--- a/library/core/src/iter/adapters/cloned.rs
+++ b/library/core/src/iter/adapters/cloned.rs
@@ -60,7 +60,6 @@ fn fold<Acc, F>(self, init: Acc, f: F) -> Acc
         self.it.map(T::clone).fold(init, f)
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> T
     where
         Self: TrustedRandomAccessNoCoerce,

diff --git a/library/core/src/iter/adapters/copied.rs b/library/core/src/iter/adapters/copied.rs
index e5f2886dcafadad5712125962ca5f9418fce1fa2..f9bfd77d7fbbff40bd337cc9e97eb199dc215207 100644 (file)
--- a/library/core/src/iter/adapters/copied.rs
+++ b/library/core/src/iter/adapters/copied.rs
@@ -81,7 +81,6 @@ fn advance_by(&mut self, n: usize) -> Result<(), usize> {
         self.it.advance_by(n)
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> T
     where
         Self: TrustedRandomAccessNoCoerce,

diff --git a/library/core/src/iter/adapters/enumerate.rs b/library/core/src/iter/adapters/enumerate.rs
index 10b4db84b3904e1a115e50dcb261d86259e17504..14a126951115cd156891c48407431d74beb20af8 100644 (file)
--- a/library/core/src/iter/adapters/enumerate.rs
+++ b/library/core/src/iter/adapters/enumerate.rs
@@ -128,7 +128,6 @@ fn advance_by(&mut self, n: usize) -> Result<(), usize> {
     }
 
     #[rustc_inherit_overflow_checks]
-    #[doc(hidden)]
     #[inline]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> <Self as Iterator>::Item
     where

diff --git a/library/core/src/iter/adapters/fuse.rs b/library/core/src/iter/adapters/fuse.rs
index fbf752c6f2024ac54e959f0ab5815eb6d375e653..8adb53c6714284c1d6376c3114c6f15c92e1d243 100644 (file)
--- a/library/core/src/iter/adapters/fuse.rs
+++ b/library/core/src/iter/adapters/fuse.rs
@@ -129,7 +129,6 @@ fn find<P>(&mut self, predicate: P) -> Option<Self::Item>
     }
 
     #[inline]
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item
     where
         Self: TrustedRandomAccessNoCoerce,

diff --git a/library/core/src/iter/adapters/map.rs b/library/core/src/iter/adapters/map.rs
index 6cbb35dc7c6292ff586bbd36d3b73f64a13c202d..9e25dbe462c91eb3648dd7fd09af0ba99de3b248 100644 (file)
--- a/library/core/src/iter/adapters/map.rs
+++ b/library/core/src/iter/adapters/map.rs
@@ -124,7 +124,6 @@ fn fold<Acc, G>(self, init: Acc, g: G) -> Acc
         self.iter.fold(init, map_fold(self.f, g))
     }
 
-    #[doc(hidden)]
     #[inline]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> B
     where

diff --git a/library/core/src/iter/adapters/zip.rs b/library/core/src/iter/adapters/zip.rs
index de44bd66501e20bb3445fdffdb700062d65c00f4..8153c8cfef133aa0c2d246d4b4169335dbeaf965 100644 (file)
--- a/library/core/src/iter/adapters/zip.rs
+++ b/library/core/src/iter/adapters/zip.rs
@@ -95,7 +95,6 @@ fn nth(&mut self, n: usize) -> Option<Self::Item> {
     }
 
     #[inline]
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item
     where
         Self: TrustedRandomAccessNoCoerce,

diff --git a/library/core/src/iter/range.rs b/library/core/src/iter/range.rs
index 0ae94c05da6583c11d3df41058fa9eee57050202..f7aeee8c9adc6f36ec1f989441ae897b94b4763c 100644 (file)
--- a/library/core/src/iter/range.rs
+++ b/library/core/src/iter/range.rs
@@ -752,7 +752,6 @@ fn advance_by(&mut self, n: usize) -> Result<(), usize> {
     }
 
     #[inline]
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item
     where
         Self: TrustedRandomAccessNoCoerce,

diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs
index 98dd1521d0e85bea969b63d583f976bd74a023ee..772a9698d84cc9b930d2e73f1cfe8125d33e027c 100644 (file)
--- a/library/core/src/slice/iter.rs
+++ b/library/core/src/slice/iter.rs
@@ -1322,7 +1322,6 @@ fn last(self) -> Option<Self::Item> {
         }
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         // SAFETY: since the caller guarantees that `i` is in bounds,
         // which means that `i` cannot overflow an `isize`, and the
@@ -1478,7 +1477,6 @@ fn last(self) -> Option<Self::Item> {
         }
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let start = idx * self.chunk_size;
         // SAFETY: the caller guarantees that `i` is in bounds,
@@ -1657,7 +1655,6 @@ fn last(self) -> Option<Self::Item> {
         }
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let start = idx * self.chunk_size;
         // SAFETY: see comments for `Chunks::__iterator_get_unchecked`.
@@ -1830,7 +1827,6 @@ fn last(mut self) -> Option<Self::Item> {
         self.next_back()
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let start = idx * self.chunk_size;
         // SAFETY: mostly identical to `Chunks::__iterator_get_unchecked`.
@@ -1984,7 +1980,6 @@ fn last(mut self) -> Option<Self::Item> {
         self.next_back()
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let start = idx * self.chunk_size;
         // SAFETY: see comments for `ChunksMut::__iterator_get_unchecked`.
@@ -2248,7 +2243,6 @@ fn last(self) -> Option<Self::Item> {
         self.iter.last()
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> &'a [T; N] {
         // SAFETY: The safety guarantees of `__iterator_get_unchecked` are
         // transferred to the caller.
@@ -2367,7 +2361,6 @@ fn last(self) -> Option<Self::Item> {
         self.iter.last()
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> &'a mut [T; N] {
         // SAFETY: The safety guarantees of `__iterator_get_unchecked` are transferred to
         // the caller.
@@ -2520,7 +2513,6 @@ fn last(self) -> Option<Self::Item> {
         }
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let end = self.v.len() - idx * self.chunk_size;
         let start = match end.checked_sub(self.chunk_size) {
@@ -2689,7 +2681,6 @@ fn last(self) -> Option<Self::Item> {
         }
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let end = self.v.len() - idx * self.chunk_size;
         let start = match end.checked_sub(self.chunk_size) {
@@ -2856,7 +2847,6 @@ fn last(mut self) -> Option<Self::Item> {
         self.next_back()
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let end = self.v.len() - idx * self.chunk_size;
         let start = end - self.chunk_size;
@@ -3016,7 +3006,6 @@ fn last(mut self) -> Option<Self::Item> {
         self.next_back()
     }
 
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let end = self.v.len() - idx * self.chunk_size;
         let start = end - self.chunk_size;

diff --git a/library/core/src/slice/iter/macros.rs b/library/core/src/slice/iter/macros.rs
index 78bf3381b4d269f8e6be66741896f2a05046023f..c05242222dde7e54c1b4b5477a2efb397073593b 100644 (file)
--- a/library/core/src/slice/iter/macros.rs
+++ b/library/core/src/slice/iter/macros.rs
@@ -325,7 +325,6 @@ fn rposition<P>(&mut self, mut predicate: P) -> Option<usize> where
                 None
             }
 
-            #[doc(hidden)]
             #[inline]
             unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
                 // SAFETY: the caller must guarantee that `i` is in bounds of

diff --git a/library/core/src/str/iter.rs b/library/core/src/str/iter.rs
index e529bccbc7999ee1ea852e4cc6cd90cab17101cc..f46acc11f2dd3a34fa74f34ae8c7e5a57663f0c5 100644 (file)
--- a/library/core/src/str/iter.rs
+++ b/library/core/src/str/iter.rs
@@ -298,7 +298,6 @@ fn rposition<P>(&mut self, predicate: P) -> Option<usize>
     }
 
     #[inline]
-    #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> u8 {
         // SAFETY: the caller must uphold the safety contract
         // for `Iterator::__iterator_get_unchecked`.

diff --git a/src/test/ui/lint/unused/unused-attr-doc-hidden.fixed b/src/test/ui/lint/unused/unused-attr-doc-hidden.fixed
new file mode 100644 (file)
index 0000000..36a1409
--- /dev/null
+++ b/src/test/ui/lint/unused/unused-attr-doc-hidden.fixed
@@ -0,0 +1,42 @@
+#![deny(unused_attributes)]
+#![crate_type = "lib"]
+// run-rustfix
+
+pub trait Trait {
+    type It;
+    const IT: ();
+    fn it0();
+    fn it1();
+    fn it2();
+}
+
+pub struct Implementor;
+
+impl Trait for Implementor {
+    
+    type It = ();
+    //~^^ ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+
+    
+    const IT: () = ();
+    //~^^ ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+
+    #[doc(alias = "aka")]
+    fn it0() {}
+    //~^^ ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+
+    #[doc(alias = "this", )]
+    fn it1() {}
+    //~^^ ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+
+    #[doc()]
+    fn it2() {}
+    //~^^ ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+    //~|  ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+}

diff --git a/src/test/ui/lint/unused/unused-attr-doc-hidden.rs b/src/test/ui/lint/unused/unused-attr-doc-hidden.rs
new file mode 100644 (file)
index 0000000..e58c4f2
--- /dev/null
+++ b/src/test/ui/lint/unused/unused-attr-doc-hidden.rs
@@ -0,0 +1,42 @@
+#![deny(unused_attributes)]
+#![crate_type = "lib"]
+// run-rustfix
+
+pub trait Trait {
+    type It;
+    const IT: ();
+    fn it0();
+    fn it1();
+    fn it2();
+}
+
+pub struct Implementor;
+
+impl Trait for Implementor {
+    #[doc(hidden)]
+    type It = ();
+    //~^^ ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+
+    #[doc(hidden)]
+    const IT: () = ();
+    //~^^ ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+
+    #[doc(hidden, alias = "aka")]
+    fn it0() {}
+    //~^^ ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+
+    #[doc(alias = "this", hidden,)]
+    fn it1() {}
+    //~^^ ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+
+    #[doc(hidden, hidden)]
+    fn it2() {}
+    //~^^ ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+    //~|  ERROR `#[doc(hidden)]` is ignored
+    //~|  WARNING this was previously accepted
+}

diff --git a/src/test/ui/lint/unused/unused-attr-doc-hidden.stderr b/src/test/ui/lint/unused/unused-attr-doc-hidden.stderr
new file mode 100644 (file)
index 0000000..fd1202a
--- /dev/null
+++ b/src/test/ui/lint/unused/unused-attr-doc-hidden.stderr
@@ -0,0 +1,67 @@
+error: `#[doc(hidden)]` is ignored on trait impl items
+  --> $DIR/unused-attr-doc-hidden.rs:16:5
+   |
+LL |     #[doc(hidden)]
+   |     ^^^^^^^^^^^^^^ help: remove this attribute
+   |
+note: the lint level is defined here
+  --> $DIR/unused-attr-doc-hidden.rs:1:9
+   |
+LL | #![deny(unused_attributes)]
+   |         ^^^^^^^^^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: whether the impl item is `doc(hidden)` or not entirely depends on the corresponding trait item
+
+error: `#[doc(hidden)]` is ignored on trait impl items
+  --> $DIR/unused-attr-doc-hidden.rs:21:5
+   |
+LL |     #[doc(hidden)]
+   |     ^^^^^^^^^^^^^^ help: remove this attribute
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: whether the impl item is `doc(hidden)` or not entirely depends on the corresponding trait item
+
+error: `#[doc(hidden)]` is ignored on trait impl items
+  --> $DIR/unused-attr-doc-hidden.rs:26:11
+   |
+LL |     #[doc(hidden, alias = "aka")]
+   |           ^^^^^^--
+   |           |
+   |           help: remove this attribute
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: whether the impl item is `doc(hidden)` or not entirely depends on the corresponding trait item
+
+error: `#[doc(hidden)]` is ignored on trait impl items
+  --> $DIR/unused-attr-doc-hidden.rs:31:27
+   |
+LL |     #[doc(alias = "this", hidden,)]
+   |                           ^^^^^^-
+   |                           |
+   |                           help: remove this attribute
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: whether the impl item is `doc(hidden)` or not entirely depends on the corresponding trait item
+
+error: `#[doc(hidden)]` is ignored on trait impl items
+  --> $DIR/unused-attr-doc-hidden.rs:36:11
+   |
+LL |     #[doc(hidden, hidden)]
+   |           ^^^^^^--
+   |           |
+   |           help: remove this attribute
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: whether the impl item is `doc(hidden)` or not entirely depends on the corresponding trait item
+
+error: `#[doc(hidden)]` is ignored on trait impl items
+  --> $DIR/unused-attr-doc-hidden.rs:36:19
+   |
+LL |     #[doc(hidden, hidden)]
+   |                   ^^^^^^ help: remove this attribute
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: whether the impl item is `doc(hidden)` or not entirely depends on the corresponding trait item
+
+error: aborting due to 6 previous errors
+