Improve error messages for typerefs a bit

reid/src/mir/display.rs

@@ -311,3 +311,13 @@ fn write_access(f: &mut std::fmt::Formatter<'_>, name: &String) -> std::fmt::Res
     f.write_char('.')?;
     Display::fmt(name, f)
 }
+
+impl std::fmt::Display for VagueType {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            VagueType::Unknown => write!(f, "Unknown"),
+            VagueType::Number => write!(f, "Number"),
+            VagueType::TypeRef(_) => write!(f, "{{unknown}}"),
+        }
+    }
+}

reid/src/mir/mod.rs

@@ -113,17 +113,14 @@ pub enum TypeKind {
     Borrow(Box<TypeKind>),
     #[error("Ptr({0})")]
     Ptr(Box<TypeKind>),
-    #[error(transparent)]
+    #[error("{0}")]
-    Vague(#[from] VagueType),
+    Vague(VagueType),
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, thiserror::Error, PartialOrd, Ord, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum VagueType {
-    #[error("Unknown")]
     Unknown,
-    #[error("Number")]
     Number,
-    #[error("TypeRef({0})")]
     TypeRef(usize),
 }