Rollup merge of #78984 - GuillaumeGomez:rustdoc-check-option, r=jyn514

Rustdoc check option

The ultimate goal behind this option would be to have `rustdoc --check` being run when you use `cargo check` as a second step.

r? `@jyn514`

src/test/rustdoc-ui/check-fail.rs

@@ -0,0 +1,21 @@
+// compile-flags: -Z unstable-options --check
+
+#![deny(missing_docs)]
+#![deny(rustdoc)]
+
+//! ```rust,testharness
+//~^ ERROR
+//! let x = 12;
+//! ```
+
+pub fn foo() {}
+//~^ ERROR
+//~^^ ERROR
+
+/// hello
+//~^ ERROR
+///
+/// ```rust,testharness
+/// let x = 12;
+/// ```
+pub fn bar() {}

src/test/rustdoc-ui/check-fail.stderr

@@ -0,0 +1,57 @@
+error: missing documentation for a function
+  --> $DIR/check-fail.rs:11:1
+   |
+LL | pub fn foo() {}
+   | ^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/check-fail.rs:3:9
+   |
+LL | #![deny(missing_docs)]
+   |         ^^^^^^^^^^^^
+
+error: missing code example in this documentation
+  --> $DIR/check-fail.rs:11:1
+   |
+LL | pub fn foo() {}
+   | ^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/check-fail.rs:4:9
+   |
+LL | #![deny(rustdoc)]
+   |         ^^^^^^^
+   = note: `#[deny(missing_doc_code_examples)]` implied by `#[deny(rustdoc)]`
+
+error: unknown attribute `testharness`. Did you mean `test_harness`?
+  --> $DIR/check-fail.rs:6:1
+   |
+LL | / //! ```rust,testharness
+LL | |
+LL | | //! let x = 12;
+LL | | //! ```
+   | |_______^
+   |
+note: the lint level is defined here
+  --> $DIR/check-fail.rs:4:9
+   |
+LL | #![deny(rustdoc)]
+   |         ^^^^^^^
+   = note: `#[deny(invalid_codeblock_attributes)]` implied by `#[deny(rustdoc)]`
+   = help: the code block will either not be tested if not marked as a rust one or the code will be wrapped inside a main function
+
+error: unknown attribute `testharness`. Did you mean `test_harness`?
+  --> $DIR/check-fail.rs:15:1
+   |
+LL | / /// hello
+LL | |
+LL | | ///
+LL | | /// ```rust,testharness
+LL | | /// let x = 12;
+LL | | /// ```
+   | |_______^
+   |
+   = help: the code block will either not be tested if not marked as a rust one or the code will be wrapped inside a main function
+
+error: aborting due to 4 previous errors
+

src/test/rustdoc-ui/check.rs

@@ -0,0 +1,11 @@
+// check-pass
+// compile-flags: -Z unstable-options --check
+
+#![warn(missing_docs)]
+//~^ WARN
+//~^^ WARN
+#![warn(rustdoc)]
+
+pub fn foo() {}
+//~^ WARN
+//~^^ WARN

src/test/rustdoc-ui/check.stderr

@@ -0,0 +1,49 @@
+warning: missing documentation for the crate
+  --> $DIR/check.rs:4:1
+   |
+LL | / #![warn(missing_docs)]
+LL | |
+LL | |
+LL | | #![warn(rustdoc)]
+LL | |
+LL | | pub fn foo() {}
+   | |_______________^
+   |
+note: the lint level is defined here
+  --> $DIR/check.rs:4:9
+   |
+LL | #![warn(missing_docs)]
+   |         ^^^^^^^^^^^^
+
+warning: missing documentation for a function
+  --> $DIR/check.rs:9:1
+   |
+LL | pub fn foo() {}
+   | ^^^^^^^^^^^^
+
+warning: missing code example in this documentation
+  --> $DIR/check.rs:4:1
+   |
+LL | / #![warn(missing_docs)]
+LL | |
+LL | |
+LL | | #![warn(rustdoc)]
+LL | |
+LL | | pub fn foo() {}
+   | |_______________^
+   |
+note: the lint level is defined here
+  --> $DIR/check.rs:7:9
+   |
+LL | #![warn(rustdoc)]
+   |         ^^^^^^^
+   = note: `#[warn(missing_doc_code_examples)]` implied by `#[warn(rustdoc)]`
+
+warning: missing code example in this documentation
+  --> $DIR/check.rs:9:1
+   |
+LL | pub fn foo() {}
+   | ^^^^^^^^^^^^^^^
+
+warning: 4 warnings emitted
+

src/test/rustdoc/check.rs

@@ -0,0 +1,5 @@
+// compile-flags: -Z unstable-options --check
+
+// @!has check/fn.foo.html
+// @!has check/index.html
+pub fn foo() {}