Add MISSING_CRATE_LEVEL_DOCS lint to the rustdoc group

Author: GuillaumeGomez

compiler/rustc_lint/src/lib.rs

@@ -70,7 +70,7 @@ use rustc_middle::ty::TyCtxt;
 use rustc_session::lint::builtin::{
     BARE_TRAIT_OBJECTS, BROKEN_INTRA_DOC_LINKS, ELIDED_LIFETIMES_IN_PATHS,
     EXPLICIT_OUTLIVES_REQUIREMENTS, INVALID_CODEBLOCK_ATTRIBUTES, INVALID_HTML_TAGS,
-    MISSING_DOC_CODE_EXAMPLES, NON_AUTOLINKS, PRIVATE_DOC_TESTS,
+    MISSING_CRATE_LEVEL_DOCS, MISSING_DOC_CODE_EXAMPLES, NON_AUTOLINKS, PRIVATE_DOC_TESTS,
 };
 use rustc_span::symbol::{Ident, Symbol};
 use rustc_span::Span;
@@ -321,6 +321,7 @@ fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
         INVALID_CODEBLOCK_ATTRIBUTES,
         MISSING_DOC_CODE_EXAMPLES,
         PRIVATE_DOC_TESTS,
+        MISSING_CRATE_LEVEL_DOCS,
         INVALID_HTML_TAGS
     );
 

src/test/rustdoc-ui/check.stderr

@@ -21,6 +21,17 @@ warning: missing documentation for a function
 LL | pub fn foo() {}
    | ^^^^^^^^^^^^
 
+warning: no documentation found for this crate's top-level module
+   |
+note: the lint level is defined here
+  --> $DIR/check.rs:7:9
+   |
+LL | #![warn(rustdoc)]
+   |         ^^^^^^^
+   = note: `#[warn(missing_crate_level_docs)]` implied by `#[warn(rustdoc)]`
+   = help: The following guide may be of use:
+           https://doc.rust-lang.org/nightly/rustdoc/how-to-write-documentation.html
+
 warning: missing code example in this documentation
   --> $DIR/check.rs:4:1
    |
@@ -45,5 +56,5 @@ warning: missing code example in this documentation
 LL | pub fn foo() {}
    | ^^^^^^^^^^^^^^^
 
-warning: 4 warnings emitted
+warning: 5 warnings emitted