From 0de93b3bf2619e284149e393e3464061f319ff1e Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Thu, 6 Jul 2017 22:21:59 -0700
Subject: [PATCH] Allow negative dynamic precedences

---
 src/compiler/prepare_grammar/flatten_grammar.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/compiler/prepare_grammar/flatten_grammar.cc b/src/compiler/prepare_grammar/flatten_grammar.cc
index ae802287..86c76a86 100644
--- a/src/compiler/prepare_grammar/flatten_grammar.cc
+++ b/src/compiler/prepare_grammar/flatten_grammar.cc
@@ -1,6 +1,7 @@
 #include "compiler/prepare_grammar/flatten_grammar.h"
 #include <vector>
 #include <cassert>
+#include <cmath>
 #include <algorithm>
 #include "compiler/prepare_grammar/extract_choices.h"
 #include "compiler/prepare_grammar/initial_syntax_grammar.h"
@@ -42,7 +43,7 @@ class FlattenRule {
           associativity_stack.push_back(metadata.params.associativity);
         }
 
-        if (metadata.params.dynamic_precedence > production.dynamic_precedence) {
+        if (abs(metadata.params.dynamic_precedence) > abs(production.dynamic_precedence)) {
           production.dynamic_precedence = metadata.params.dynamic_precedence;
         }