Make ret and fail stmts have 0 out-edges, Closes #250.

src/boot/me/typestate.ml

@@ -865,6 +865,11 @@ let rec build_flow_graph_for_stmt
         | Ast.STMT_block b ->
             blk predecessors b
 
+        | Ast.STMT_fail
+        | Ast.STMT_ret _ ->
+            connect predecessors [s.id];
+            []
+
         | _ ->
             connect predecessors [s.id];
             [s.id]

src/comp/front/lexer.rs

@@ -665,12 +665,9 @@ impure fn next_token(reader rdr) -> token.token {
         case ('%') {
             ret binop(rdr, token.PERCENT);
         }
-
     }
 
-    log "lexer stopping at ";
-    log c;
-    ret token.EOF;
+    fail;
 }
 
 

src/comp/middle/fold.rs

@@ -701,7 +701,7 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
 
     }
 
-    ret e;
+    fail;
 }
 
 
@@ -724,7 +724,7 @@ fn fold_stmt[ENV](&ENV env, ast_fold[ENV] fld, &@stmt s) -> @stmt {
             ret fld.fold_stmt_expr(env_, s.span, ee);
         }
     }
-    ret s;
+    fail;
 }
 
 fn fold_block[ENV](&ENV env, ast_fold[ENV] fld, &block blk) -> block {

src/comp/middle/ty.rs

@@ -373,7 +373,7 @@ fn fold_ty(ty_fold fld, @t ty) -> @t {
         case (ty_param(_))      { ret fld.fold_simple_ty(ty); }
     }
 
-    ret ty;
+    fail;
 }
 
 // Type utilities