From 6080c3b4ba3afb918977d4354121ddac01c446c9 Mon Sep 17 00:00:00 2001
From: Rosen Penev <rosenp@gmail.com>
Date: Tue, 7 Apr 2020 20:14:00 -0700
Subject: [PATCH] Math.hxx: move cmath include out of define

The _GLIBCXX_USE_C99_MATH macro is defined in glibcxx by c++config.h, which
gets included by every header. Which means a header needs to be present.

(cherry picked from commit 79e9aff3382d8b7521318c44835a6dd6b284e2c1)
---
 src/util/Math.hxx | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/util/Math.hxx b/src/util/Math.hxx
index 9784c0b64..ad5cffd82 100644
--- a/src/util/Math.hxx
+++ b/src/util/Math.hxx
@@ -30,11 +30,16 @@
 #ifndef MATH_HXX
 #define MATH_HXX
 
+#include <cmath>
+
+/*
+ * C99 math can be optionally omitted with gcc's libstdc++.
+ * Use boost if unavailable.
+ */
 #if (defined(__GLIBCPP__) || defined(__GLIBCXX__)) && !defined(_GLIBCXX_USE_C99_MATH)
 #include <boost/math/special_functions/round.hpp>
 using boost::math::lround;
 #else
-#include <cmath>
 using std::lround;
 #endif