feat: add anonymous symbol.

Author: Shylock-Hg

tigerc/src/ident_pool.rs

@@ -26,6 +26,8 @@ symbols! {
         TOK_LET: "let",
         TOK_IN: "in",
         TOK_END: "end",
+        // use for inner symbol
+        REVERSED_ANONYMOUS: "__anonymous",
     }
 }
 

tigerc/src/ir.rs

@@ -1,6 +1,6 @@
 use std::hash::Hash;
 
-use crate::ident_pool::Symbol;
+use crate::ident_pool::{kw, Symbol};
 use crate::temp::{Label, Temp};
 
 // Identify different symbol with same name
@@ -24,6 +24,10 @@ impl LowerIdent {
             },
         }
     }
+
+    pub fn new_anonymous() -> LowerIdent {
+        LowerIdent::new(kw::REVERSED_ANONYMOUS)
+    }
 }
 
 impl PartialEq for LowerIdent {