From 9cae3a759486e8dd608b5ff3c119b3a98f86ac6c Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Tue, 27 Nov 2012 00:41:35 +0100
Subject: [PATCH] Only run the pkg-config line for Eigen3 once.

Also, print an error message if pkg-config has failed.
---
 Makefile | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index f7ba81e..1ab3d9c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,13 @@
 GTEST_DIR = /usr/src/gtest
 
+EIGEN_CXXFLAGS := $(shell pkg-config --cflags eigen3)
+ifeq ($(EIGEN_CXXFLAGS),)
+$(error Empty EIGEN_CXXFLAGS. You probably need to install Eigen3)
+endif
+
 CC=gcc
 CXX=g++
-CXXFLAGS=-Wall -g -I$(GTEST_DIR)/include $(shell pkg-config --cflags eigen3 )
+CXXFLAGS=-Wall -g -I$(GTEST_DIR)/include $(EIGEN_CXXFLAGS)
 LDFLAGS=-lSDL -lSDL_image -lGL -lrt -lpthread
 RANLIB=ranlib
 
-- 
2.39.2