validate doc(masked)

Author: Lukas Markeffsky

compiler/rustc_passes/messages.ftl

@@ -211,6 +211,17 @@ passes_doc_keyword_not_mod =
 passes_doc_keyword_only_impl =
     `#[doc(keyword = "...")]` should be used on impl blocks
 
+passes_doc_masked_not_extern_crate_self =
+    this attribute cannot be applied to an `extern crate self` item
+    .label = not applicable on `extern crate self` items
+    .extern_crate_self_label = `extern crate self` defined here
+
+passes_doc_masked_only_extern_crate =
+    this attribute can only be applied to an `extern crate` item
+    .label = only applicable on `extern crate` items
+    .not_an_extern_crate_label = not an `extern crate` item
+    .note = read <https://doc.rust-lang.org/unstable-book/language-features/doc-masked.html> for more information
+
 passes_doc_test_literal = `#![doc(test(...)]` does not take a literal
 
 passes_doc_test_takes_list =

compiler/rustc_passes/src/check_attr.rs

@@ -878,6 +878,44 @@ impl CheckAttrVisitor<'_> {
         }
     }
 
+    fn check_doc_masked(
+        &self,
+        attr: &Attribute,
+        meta: &NestedMetaItem,
+        hir_id: HirId,
+        target: Target,
+    ) -> bool {
+        if target != Target::ExternCrate {
+            self.tcx.emit_spanned_lint(
+                INVALID_DOC_ATTRIBUTES,
+                hir_id,
+                meta.span(),
+                errors::DocMaskedOnlyExternCrate {
+                    attr_span: meta.span(),
+                    item_span: (attr.style == AttrStyle::Outer)
+                        .then(|| self.tcx.hir().span(hir_id)),
+                },
+            );
+            return false;
+        }
+
+        if self.tcx.extern_mod_stmt_cnum(hir_id.owner).is_none() {
+            self.tcx.emit_spanned_lint(
+                INVALID_DOC_ATTRIBUTES,
+                hir_id,
+                meta.span(),
+                errors::DocMaskedNotExternCrateSelf {
+                    attr_span: meta.span(),
+                    item_span: (attr.style == AttrStyle::Outer)
+                        .then(|| self.tcx.hir().span(hir_id)),
+                },
+            );
+            return false;
+        }
+
+        true
+    }
+
     /// Checks that an attribute is *not* used at the crate level. Returns `true` if valid.
     fn check_attr_not_crate_level(
         &self,
@@ -1048,6 +1086,17 @@ impl CheckAttrVisitor<'_> {
                             is_valid = false;
                         }
 
+                        sym::masked
+                            if !self.check_doc_masked(
+                                attr,
+                                meta,
+                                hir_id,
+                                target,
+                            ) =>
+                        {
+                            is_valid = false;
+                        }
+
                         // no_default_passes: deprecated
                         // passes: deprecated
                         // plugins: removed, but rustdoc warns about it itself

compiler/rustc_passes/src/errors.rs

@@ -267,6 +267,25 @@ pub struct DocInlineOnlyUse {
     pub item_span: Option<Span>,
 }
 
+#[derive(LintDiagnostic)]
+#[diag(passes_doc_masked_only_extern_crate)]
+#[note]
+pub struct DocMaskedOnlyExternCrate {
+    #[label]
+    pub attr_span: Span,
+    #[label(passes_not_an_extern_crate_label)]
+    pub item_span: Option<Span>,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(passes_doc_masked_not_extern_crate_self)]
+pub struct DocMaskedNotExternCrateSelf {
+    #[label]
+    pub attr_span: Span,
+    #[label(passes_extern_crate_self_label)]
+    pub item_span: Option<Span>,
+}
+
 #[derive(Diagnostic)]
 #[diag(passes_doc_attr_not_crate_level)]
 pub struct DocAttrNotCrateLevel<'a> {

tests/rustdoc-ui/lints/invalid-doc-attr.rs

@@ -1,5 +1,10 @@
 #![crate_type = "lib"]
 #![deny(warnings)]
+#![feature(doc_masked)]
+
+#![doc(masked)]
+//~^ ERROR this attribute can only be applied to an `extern crate` item
+//~| WARN is being phased out
 
 #[doc(test(no_crate_inject))]
 //~^ ERROR can only be applied at the crate level
@@ -30,3 +35,13 @@ pub mod bar {
 //~^^ ERROR conflicting doc inlining attributes
 //~|  HELP remove one of the conflicting attributes
 pub use bar::baz;
+
+#[doc(masked)]
+//~^ ERROR this attribute can only be applied to an `extern crate` item
+//~| WARN is being phased out
+pub struct Masked;
+
+#[doc(masked)]
+//~^ ERROR this attribute cannot be applied to an `extern crate self` item
+//~| WARN is being phased out
+pub extern crate self as reexport;

tests/rustdoc-ui/lints/invalid-doc-attr.stderr

@@ -1,5 +1,5 @@
 error: this attribute can only be applied at the crate level
-  --> $DIR/invalid-doc-attr.rs:4:7
+  --> $DIR/invalid-doc-attr.rs:9:7
    |
 LL | #[doc(test(no_crate_inject))]
    |       ^^^^^^^^^^^^^^^^^^^^^
@@ -19,7 +19,7 @@ LL | #![doc(test(no_crate_inject))]
    |  +
 
 error: this attribute can only be applied to a `use` item
-  --> $DIR/invalid-doc-attr.rs:9:7
+  --> $DIR/invalid-doc-attr.rs:14:7
    |
 LL | #[doc(inline)]
    |       ^^^^^^ only applicable on `use` items
@@ -32,7 +32,7 @@ LL | pub fn foo() {}
    = note: read <https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#inline-and-no_inline> for more information
 
 error: this attribute can only be applied at the crate level
-  --> $DIR/invalid-doc-attr.rs:15:12
+  --> $DIR/invalid-doc-attr.rs:20:12
    |
 LL |     #![doc(test(no_crate_inject))]
    |            ^^^^^^^^^^^^^^^^^^^^^
@@ -42,7 +42,7 @@ LL |     #![doc(test(no_crate_inject))]
    = note: read <https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#at-the-crate-level> for more information
 
 error: conflicting doc inlining attributes
-  --> $DIR/invalid-doc-attr.rs:28:7
+  --> $DIR/invalid-doc-attr.rs:33:7
    |
 LL | #[doc(inline)]
    |       ^^^^^^ this attribute...
@@ -51,8 +51,43 @@ LL | #[doc(no_inline)]
    |
    = help: remove one of the conflicting attributes
 
+error: this attribute can only be applied to an `extern crate` item
+  --> $DIR/invalid-doc-attr.rs:39:7
+   |
+LL | #[doc(masked)]
+   |       ^^^^^^ only applicable on `extern crate` items
+...
+LL | pub struct Masked;
+   | ----------------- not an `extern crate` item
+   |
+   = 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/unstable-book/language-features/doc-masked.html> for more information
+
+error: this attribute cannot be applied to an `extern crate self` item
+  --> $DIR/invalid-doc-attr.rs:44:7
+   |
+LL | #[doc(masked)]
+   |       ^^^^^^ not applicable on `extern crate self` items
+...
+LL | pub extern crate self as reexport;
+   | --------------------------------- `extern crate self` defined here
+   |
+   = 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: this attribute can only be applied to an `extern crate` item
+  --> $DIR/invalid-doc-attr.rs:5:8
+   |
+LL | #![doc(masked)]
+   |        ^^^^^^ only applicable on `extern crate` items
+   |
+   = 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/unstable-book/language-features/doc-masked.html> for more information
+
 error: this attribute can only be applied at the crate level
-  --> $DIR/invalid-doc-attr.rs:19:11
+  --> $DIR/invalid-doc-attr.rs:24:11
    |
 LL |     #[doc(test(no_crate_inject))]
    |           ^^^^^^^^^^^^^^^^^^^^^
@@ -62,7 +97,7 @@ LL |     #[doc(test(no_crate_inject))]
    = note: read <https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#at-the-crate-level> for more information
 
 error: this attribute can only be applied to a `use` item
-  --> $DIR/invalid-doc-attr.rs:22:11
+  --> $DIR/invalid-doc-attr.rs:27:11
    |
 LL |     #[doc(inline)]
    |           ^^^^^^ only applicable on `use` items
@@ -74,5 +109,5 @@ LL |     pub fn baz() {}
    = 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#inline-and-no_inline> for more information
 
-error: aborting due to 6 previous errors
+error: aborting due to 9 previous errors