Auto merge of #104889 - GuillaumeGomez:fix-impl-block-in-const-expr, r=notriddle

Fix impl block in const expr

Fixes #83026.

The problem was that we didn't visit block expressions. Considering how big the [walk_expr](https://doc.rust-lang.org/nightly/nightly-rustc/src/rustc_hir/intravisit.rs.html#678) function is, I decided to instead implement the `hir` visitor on the struct. It also answers the question which was in a comment for `RustdocVisitor`: we should have used a visitor instead of our ad-hoc implementation.

Adding this visitor also added some extra checks that weren't present before (check changes in `rustdoc-ui` tests).

r? `@notriddle`

5 files changed, 77 insertions, 7 deletions

diff --git a/src/test/rustdoc-ui/infinite-recursive-type-impl-trait-return.rs b/src/test/rustdoc-ui/infinite-recursive-type-impl-trait-return.rs
index 4b1e04234c8..939da186fbc 100644
--- a/src/test/rustdoc-ui/infinite-recursive-type-impl-trait-return.rs
+++ b/src/test/rustdoc-ui/infinite-recursive-type-impl-trait-return.rs
@@ -1,12 +1,10 @@
-// check-pass
 // normalize-stderr-test: "`.*`" -> "`DEF_ID`"
 // normalize-stdout-test: "`.*`" -> "`DEF_ID`"
 // edition:2018
 
 pub async fn f() -> impl std::fmt::Debug {
-    // rustdoc doesn't care that this is infinitely sized
     #[derive(Debug)]
-    enum E {
+    enum E { //~ ERROR
         This(E),
         Unit,
     }
diff --git a/src/test/rustdoc-ui/infinite-recursive-type-impl-trait-return.stderr b/src/test/rustdoc-ui/infinite-recursive-type-impl-trait-return.stderr
new file mode 100644
index 00000000000..aff7402bc91
--- /dev/null
+++ b/src/test/rustdoc-ui/infinite-recursive-type-impl-trait-return.stderr
@@ -0,0 +1,16 @@
+error[E0072]: recursive type `DEF_ID` has infinite size
+  --> $DIR/infinite-recursive-type-impl-trait-return.rs:7:5
+   |
+LL |     enum E {
+   |     ^^^^^^
+LL |         This(E),
+   |              - recursive without indirection
+   |
+help: insert some indirection (e.g., a `DEF_ID`) to break the cycle
+   |
+LL |         This(Box<E>),
+   |              ++++ +
+
+error: aborting due to previous error
+
+For more information about this error, try `DEF_ID`.
diff --git a/src/test/rustdoc-ui/infinite-recursive-type-impl-trait.rs b/src/test/rustdoc-ui/infinite-recursive-type-impl-trait.rs
index ac79582fb3f..ac517257498 100644
--- a/src/test/rustdoc-ui/infinite-recursive-type-impl-trait.rs
+++ b/src/test/rustdoc-ui/infinite-recursive-type-impl-trait.rs
@@ -1,8 +1,5 @@
-// check-pass
-
 fn f() -> impl Sized {
-    // rustdoc doesn't care that this is infinitely sized
-    enum E {
+    enum E { //~ ERROR
         V(E),
     }
     unimplemented!()
diff --git a/src/test/rustdoc-ui/infinite-recursive-type-impl-trait.stderr b/src/test/rustdoc-ui/infinite-recursive-type-impl-trait.stderr
new file mode 100644
index 00000000000..a61577bd14a
--- /dev/null
+++ b/src/test/rustdoc-ui/infinite-recursive-type-impl-trait.stderr
@@ -0,0 +1,16 @@
+error[E0072]: recursive type `f::E` has infinite size
+  --> $DIR/infinite-recursive-type-impl-trait.rs:2:5
+   |
+LL |     enum E {
+   |     ^^^^^^
+LL |         V(E),
+   |           - recursive without indirection
+   |
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to break the cycle
+   |
+LL |         V(Box<E>),
+   |           ++++ +
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0072`.
diff --git a/src/test/rustdoc/impl-in-const-block.rs b/src/test/rustdoc/impl-in-const-block.rs
new file mode 100644
index 00000000000..b44e7135246
--- /dev/null
+++ b/src/test/rustdoc/impl-in-const-block.rs
@@ -0,0 +1,43 @@
+// Regression test for #83026.
+// The goal of this test is to ensure that impl blocks inside
+// const expressions are documented as well.
+
+#![crate_name = "foo"]
+
+// @has 'foo/struct.A.html'
+// @has - '//*[@id="method.new"]/*[@class="code-header"]' 'pub fn new() -> A'
+// @has - '//*[@id="method.bar"]/*[@class="code-header"]' 'pub fn bar(&self)'
+// @has - '//*[@id="method.woo"]/*[@class="code-header"]' 'pub fn woo(&self)'
+// @has - '//*[@id="method.yoo"]/*[@class="code-header"]' 'pub fn yoo()'
+// @has - '//*[@id="method.yuu"]/*[@class="code-header"]' 'pub fn yuu()'
+pub struct A;
+
+const _: () = {
+    impl A {
+        const FOO: () = {
+            impl A {
+                pub fn woo(&self) {}
+            }
+        };
+
+        pub fn new() -> A {
+            A
+        }
+    }
+};
+pub const X: () = {
+    impl A {
+        pub fn bar(&self) {}
+    }
+};
+
+fn foo() {
+    impl A {
+        pub fn yoo() {}
+    }
+    const _: () = {
+        impl A {
+            pub fn yuu() {}
+        }
+    };
+}