Add production name in ParseError

for debugging

schala-lang/codegen/src/lib.rs

@@ -32,7 +32,10 @@ impl Fold for RecursiveDescentFn {
         if self.parse_level != 0 {
           self.parse_level -= 1;
         }
-        result
+        result.map_err(|mut parse_error: ParseError| {
+          parse_error.production_name = Some(stringify!(#ident).to_string());
+          parse_error
+        })
       }
     };
     i.block = Box::new(new_block);

schala-lang/language/src/parsing.rs

@@ -160,13 +160,14 @@ use crate::ast::*;
 /// Represents a parsing error
 #[derive(Debug)]
 pub struct ParseError {
+  pub production_name: Option<String>,
   pub msg: String,
   pub token: Token
 }
 
 impl ParseError {
   fn new_with_token<T, M>(msg: M, token: Token) -> ParseResult<T> where M: Into<String> {
-    Err(ParseError { msg: msg.into(), token })
+    Err(ParseError { msg: msg.into(), token, production_name: None })
   }
 }