diff --git a/compiler/rustc_mir/src/borrow_check/region_infer/mod.rs b/compiler/rustc_mir/src/borrow_check/region_infer/mod.rs
index 053ca7c23d2..6264f521c62 100644
--- a/compiler/rustc_mir/src/borrow_check/region_infer/mod.rs
+++ b/compiler/rustc_mir/src/borrow_check/region_infer/mod.rs
@@ -1225,7 +1225,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// it. However, it works pretty well in practice. In particular,
     /// this is needed to deal with projection outlives bounds like
     ///
-    /// ```ignore (MIR syntax)
+    /// ```ignore (internal compiler representation so lifetime syntax is invalid)
     /// <T as Foo<'0>>::Item: '1
     /// ```
     ///
diff --git a/compiler/rustc_trait_selection/src/opaque_types.rs b/compiler/rustc_trait_selection/src/opaque_types.rs
index 4f351ab176d..618f3e045e7 100644
--- a/compiler/rustc_trait_selection/src/opaque_types.rs
+++ b/compiler/rustc_trait_selection/src/opaque_types.rs
@@ -41,13 +41,10 @@ pub struct OpaqueTypeDecl<'tcx> {
     /// The span of this particular definition of the opaque type. So
     /// for example:
     ///
-    /// ```
+    /// ```ignore (incomplete snippet)
     /// type Foo = impl Baz;
     /// fn bar() -> Foo {
     /// //          ^^^ This is the span we are looking for!
-    /// // ...
-    /// # unimplemented!()
-    /// }
     /// ```
     ///
     /// In cases where the fn returns `(impl Trait, impl Trait)` or