Rollup merge of rust-lang#102954 - GuillaumeGomez:cfg-hide-attr-checks, r=Manishearth

Add missing checks for `doc(cfg_hide(...))`

Part of  rust-lang#43781.

The `doc(cfg_hide(...))` attribute can only be used at the crate level and takes a list of attributes as argument.

r? ```@Manishearth```

Author: Dylan-DPC

compiler/rustc_error_messages/locales/en-US/passes.ftl

@@ -145,6 +145,9 @@ passes_doc_test_takes_list =
 passes_doc_primitive =
     `doc(primitive)` should never have been stable
 
+passes_doc_cfg_hide_takes_list =
+    `#[doc(cfg_hide(...)]` takes a list of attributes
+
 passes_doc_test_unknown_any =
     unknown `doc` attribute `{$path}`
 

compiler/rustc_passes/src/check_attr.rs

@@ -934,6 +934,22 @@ impl CheckAttrVisitor<'_> {
         is_valid
     }
 
+    /// Check that the `#![doc(cfg_hide(...))]` attribute only contains a list of attributes.
+    /// Returns `true` if valid.
+    fn check_doc_cfg_hide(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
+        if meta.meta_item_list().is_some() {
+            true
+        } else {
+            self.tcx.emit_spanned_lint(
+                INVALID_DOC_ATTRIBUTES,
+                hir_id,
+                meta.span(),
+                errors::DocCfgHideTakesList,
+            );
+            false
+        }
+    }
+
     /// Runs various checks on `#[doc]` attributes. Returns `true` if valid.
     ///
     /// `specified_inline` should be initialized to `None` and kept for the scope
@@ -987,6 +1003,13 @@ impl CheckAttrVisitor<'_> {
                             is_valid = false;
                         }
 
+                        sym::cfg_hide
+                            if !self.check_attr_crate_level(attr, meta, hir_id)
+                                || !self.check_doc_cfg_hide(meta, hir_id) =>
+                        {
+                            is_valid = false;
+                        }
+
                         sym::inline | sym::no_inline
                             if !self.check_doc_inline(
                                 attr,

compiler/rustc_passes/src/errors.rs

@@ -271,6 +271,10 @@ pub struct DocTestUnknown {
 #[diag(passes::doc_test_takes_list)]
 pub struct DocTestTakesList;
 
+#[derive(LintDiagnostic)]
+#[diag(passes::doc_cfg_hide_takes_list)]
+pub struct DocCfgHideTakesList;
+
 #[derive(LintDiagnostic)]
 #[diag(passes::doc_primitive)]
 pub struct DocPrimitive;

src/test/rustdoc-ui/doc_cfg_hide.rs

@@ -0,0 +1,11 @@
+#![feature(doc_cfg_hide)]
+#![deny(warnings)]
+
+#![doc(cfg_hide = "test")] //~ ERROR
+//~^ WARN
+#![doc(cfg_hide)] //~ ERROR
+//~^ WARN
+
+#[doc(cfg_hide(doc))] //~ ERROR
+//~^ WARN
+pub fn foo() {}

src/test/rustdoc-ui/doc_cfg_hide.stderr

@@ -0,0 +1,40 @@
+error: this attribute can only be applied at the crate level
+  --> $DIR/doc_cfg_hide.rs:9:7
+   |
+LL | #[doc(cfg_hide(doc))]
+   |       ^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #82730 <https://github.com/rust-lang/rust/issues/82730>
+   = note: read <https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#at-the-crate-level> for more information
+note: the lint level is defined here
+  --> $DIR/doc_cfg_hide.rs:2:9
+   |
+LL | #![deny(warnings)]
+   |         ^^^^^^^^
+   = note: `#[deny(invalid_doc_attributes)]` implied by `#[deny(warnings)]`
+help: to apply to the crate, use an inner attribute
+   |
+LL | #![doc(cfg_hide(doc))]
+   | ~~~~~~~~~~~~~~~~~~~~~~
+
+error: `#[doc(cfg_hide(...)]` takes a list of attributes
+  --> $DIR/doc_cfg_hide.rs:4:8
+   |
+LL | #![doc(cfg_hide = "test")]
+   |        ^^^^^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #82730 <https://github.com/rust-lang/rust/issues/82730>
+
+error: `#[doc(cfg_hide(...)]` takes a list of attributes
+  --> $DIR/doc_cfg_hide.rs:6:8
+   |
+LL | #![doc(cfg_hide)]
+   |        ^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #82730 <https://github.com/rust-lang/rust/issues/82730>
+
+error: aborting due to 3 previous errors
+