checkpoint; builds again

src/backend/error.rs

@@ -41,6 +41,8 @@ pub enum BackendError {
     Write(#[from] cranelift_object::object::write::Error),
     #[error("Invalid type cast from {from} to {to}")]
     InvalidTypeCast { from: PrimitiveType, to: Type },
+    #[error("Unknown string constant '{0}")]
+    UnknownString(ArcIntern<String>),
 }
 
 impl From<BackendError> for Diagnostic<usize> {
@@ -69,6 +71,8 @@ impl From<BackendError> for Diagnostic<usize> {
             BackendError::InvalidTypeCast { from, to } => Diagnostic::error().with_message(
                 format!("Internal error trying to cast from {} to {}", from, to),
             ),
+            BackendError::UnknownString(str) => Diagnostic::error()
+                .with_message(format!("Unknown string found trying to compile: '{}'", str)),
         }
     }
 }
@@ -119,6 +123,11 @@ impl PartialEq for BackendError {
                 } => from1 == from2 && to1 == to2,
                 _ => false,
             },
+
+            BackendError::UnknownString(a) => match other {
+                BackendError::UnknownString(b) => a == b,
+                _ => false,
+            },
         }
     }
 }