Add ui test for check_private_items config

tests/ui-toml/private-doc-errors/clippy.toml

@@ -0,0 +1 @@
+check-private-items = true

tests/ui-toml/private-doc-errors/doc_lints.rs

@@ -0,0 +1,54 @@
+#![deny(
+    clippy::unnecessary_safety_doc,
+    clippy::missing_errors_doc,
+    clippy::missing_panics_doc
+)]
+
+/// This is a private function, skip to match behavior with `missing_safety_doc`.
+///
+/// # Safety
+///
+/// Boo!
+fn you_dont_see_me() {
+    //~^ ERROR: safe function's docs have unnecessary `# Safety` section
+    unimplemented!();
+}
+
+mod private_mod {
+    /// This is public but unexported function.
+    ///
+    /// # Safety
+    ///
+    /// Very safe!
+    pub fn only_crate_wide_accessible() -> Result<(), ()> {
+        //~^ ERROR: safe function's docs have unnecessary `# Safety` section
+        //~| ERROR: docs for function returning `Result` missing `# Errors` section
+        unimplemented!();
+    }
+}
+
+pub struct S;
+
+impl S {
+    /// Private, fine again to stay consistent with `missing_safety_doc`.
+    ///
+    /// # Safety
+    ///
+    /// Unnecessary!
+    fn private(&self) {
+        //~^ ERROR: safe function's docs have unnecessary `# Safety` section
+        //~| ERROR: docs for function which may panic missing `# Panics` section
+        panic!();
+    }
+}
+
+#[doc(hidden)]
+pub mod __macro {
+    pub struct T;
+    impl T {
+        pub unsafe fn f() {}
+        //~^ ERROR: unsafe function's docs miss `# Safety` section
+    }
+}
+
+fn main() {}

tests/ui-toml/private-doc-errors/doc_lints.stderr

@@ -0,0 +1,64 @@
+error: safe function's docs have unnecessary `# Safety` section
+  --> $DIR/doc_lints.rs:12:1
+   |
+LL | fn you_dont_see_me() {
+   | ^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/doc_lints.rs:2:5
+   |
+LL |     clippy::unnecessary_safety_doc,
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: safe function's docs have unnecessary `# Safety` section
+  --> $DIR/doc_lints.rs:23:5
+   |
+LL |     pub fn only_crate_wide_accessible() -> Result<(), ()> {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: docs for function returning `Result` missing `# Errors` section
+  --> $DIR/doc_lints.rs:23:5
+   |
+LL |     pub fn only_crate_wide_accessible() -> Result<(), ()> {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/doc_lints.rs:3:5
+   |
+LL |     clippy::missing_errors_doc,
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: safe function's docs have unnecessary `# Safety` section
+  --> $DIR/doc_lints.rs:38:5
+   |
+LL |     fn private(&self) {
+   |     ^^^^^^^^^^^^^^^^^
+
+error: docs for function which may panic missing `# Panics` section
+  --> $DIR/doc_lints.rs:38:5
+   |
+LL |     fn private(&self) {
+   |     ^^^^^^^^^^^^^^^^^
+   |
+note: first possible panic found here
+  --> $DIR/doc_lints.rs:41:9
+   |
+LL |         panic!();
+   |         ^^^^^^^^
+note: the lint level is defined here
+  --> $DIR/doc_lints.rs:4:5
+   |
+LL |     clippy::missing_panics_doc
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: unsafe function's docs miss `# Safety` section
+  --> $DIR/doc_lints.rs:49:9
+   |
+LL |         pub unsafe fn f() {}
+   |         ^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::missing-safety-doc` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::missing_safety_doc)]`
+
+error: aborting due to 6 previous errors
+