iter ct.2.2-doctidy: refresh stale doc-comments on UnknownCtorInPattern and mono_xmod_ctor_pattern

crates/ailang-check/src/lib.rs

@@ -345,8 +345,11 @@ pub enum CheckError {
     #[error("type `{ty}` has no constructor `{ctor}`")]
     UnknownCtor { ty: String, ctor: String },
 
-    /// A pattern referenced a ctor not in [`Env::ctor_index`]. Code:
-    /// `unknown-ctor-in-pattern`.
+    /// A pattern referenced a ctor that does not exist in the
+    /// scrutinee's resolved [`TypeDef`]. The Pattern::Ctor lookup
+    /// is type-driven (post-ct.2): it walks `td.ctors` for the
+    /// `expected` Type::Con's TypeDef and reports this code when
+    /// no ctor of that name is present. Code: `unknown-ctor-in-pattern`.
     #[error("unknown constructor `{0}` in pattern")]
     UnknownCtorInPattern(String),