From 3bc86fb237b668e738a78397be04c603e7cf083b Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 30 Aug 2019 16:39:52 -0500
Subject: [PATCH] [algs] Fix hb_inc/dec signature

---
 src/hb-algs.hh   | 5 +++--
 src/test-algs.cc | 4 ++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/hb-algs.hh b/src/hb-algs.hh
index 78b86f37a..6b74a2532 100644
--- a/src/hb-algs.hh
+++ b/src/hb-algs.hh
@@ -82,6 +82,7 @@ HB_FUNCOBJ (hb_bool);
 struct
 {
   private:
+
   template <typename T> constexpr auto
   impl (const T& v, hb_priority<1>) const HB_RETURN (uint32_t, hb_deref (v).hash ())
 
@@ -997,13 +998,13 @@ HB_FUNCOBJ (hb_neg);
 struct
 {
   template <typename T> constexpr auto
-  operator () (const T &a) const HB_AUTO_RETURN (++a)
+  operator () (T &a) const HB_AUTO_RETURN (++a)
 }
 HB_FUNCOBJ (hb_inc);
 struct
 {
   template <typename T> constexpr auto
-  operator () (const T &a) const HB_AUTO_RETURN (--a)
+  operator () (T &a) const HB_AUTO_RETURN (--a)
 }
 HB_FUNCOBJ (hb_dec);
 
diff --git a/src/test-algs.cc b/src/test-algs.cc
index 333a89242..f8b8ff666 100644
--- a/src/test-algs.cc
+++ b/src/test-algs.cc
@@ -87,5 +87,9 @@ main (int argc, char **argv)
   assert (hb_add (2) (5) == 7);
   assert (hb_add (5) (2) == 7);
 
+  x = 1;
+  assert (++hb_inc (x) == 3);
+  assert (x == 3);
+
   return 0;
 }