From 768b80f4c91f2dddb5f71f97c88c20c7a6ad71a9 Mon Sep 17 00:00:00 2001
From: Elliott Sales de Andrade <quantum.analyst@gmail.com>
Date: Sun, 3 Feb 2019 02:57:38 -0500
Subject: [PATCH] Allow building against external GTest with autotools.

Signed-off-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>
---
 configure.ac          | 31 ++++++++++++++++++++++++++-----
 test/Makefile.am      |  5 ++++-
 test/unit/Makefile.am |  8 ++++----
 3 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/configure.ac b/configure.ac
index 712720fb..0d5a45e4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -263,15 +263,36 @@ fi
 AC_SUBST(MUTEX_SETTING,$MUTEX_SETTING)
 AC_SUBST(THREAD_LIB,$THREAD_LIB)
 
+dnl ---------------------------------------------------------------------------
+dnl Check for external Google Test
+dnl ---------------------------------------------------------------------------
+
+AC_ARG_WITH(external-gtest,
+            AS_HELP_STRING([--with-external-gtest],
+               [Whether to use external Google Test]),,)
+
+if test "x$with_external_gtest" == "xyes" ; then
+    AC_MSG_RESULT([using external GTest.])
+    PKG_CHECK_MODULES([GTEST], [gtest >= 1.8.0])
+else
+    AC_MSG_RESULT([using internal GTest.])
+    GTEST_LIBS="\$(top_builddir)/test/googletest/libgtest.la"
+fi
+AM_CONDITIONAL(USE_EXTERNAL_GTEST, [test "x$with_external_gtest" == "xyes"])
+AC_SUBST(GTEST_CFLAGS,$GTEST_CFLAGS)
+AC_SUBST(GTEST_LIBS,$GTEST_LIBS)
+
 AC_CONFIG_FILES([Makefile cmake/Makefile src/Makefile
                  test/Makefile test/gie/Makefile test/gigs/Makefile test/unit/Makefile
-                 test/googletest/Makefile test/googletest/include/Makefile
-                 test/googletest/include/gtest/Makefile
-                 test/googletest/include/gtest/internal/Makefile
-                 test/googletest/include/gtest/internal/custom/Makefile
-                 test/googletest/src/Makefile
                  man/Makefile man/man1/Makefile man/man3/Makefile nad/Makefile
                  jniwrap/Makefile jniwrap/org.osgeo.proj/Makefile jniwrap/org.osgeo.proj/org/Makefile jniwrap/org.osgeo.proj/org/proj4/Makefile])
+if ! test "x$with_external_gtest" = "xyes" ; then
+    AC_CONFIG_FILES([test/googletest/Makefile test/googletest/include/Makefile
+                     test/googletest/include/gtest/Makefile
+                     test/googletest/include/gtest/internal/Makefile
+                     test/googletest/include/gtest/internal/custom/Makefile
+                     test/googletest/src/Makefile])
+fi
 AC_CONFIG_FILES([nad/install], [chmod +x nad/install])
 
 AC_CONFIG_FILES([proj.pc])
diff --git a/test/Makefile.am b/test/Makefile.am
index 8ea641b9..4590b37c 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -7,4 +7,7 @@ EXTRA_DIST = CMakeLists.txt
 # libtestmain_la_LDFLAGS = -no-undefined
 # libtestmain_la_SOURCES = test_main.cpp
 
-SUBDIRS = googletest . gie gigs unit
+if !USE_EXTERNAL_GTEST
+MAYBE_GTEST = googletest
+endif
+SUBDIRS = $(MAYBE_GTEST) . gie gigs unit
diff --git a/test/unit/Makefile.am b/test/unit/Makefile.am
index 65132be7..7510ef5d 100644
--- a/test/unit/Makefile.am
+++ b/test/unit/Makefile.am
@@ -4,7 +4,7 @@ EXTRA_DIST = CMakeLists.txt
 
 noinst_HEADERS = gtest_include.h
 
-AM_CPPFLAGS = -I$(top_srcdir)/src -I$(top_srcdir)/test -I$(top_srcdir)/test/googletest/include
+AM_CPPFLAGS = -I$(top_srcdir)/src -I$(top_srcdir)/test @GTEST_CFLAGS@
 AM_CXXFLAGS = @CXX_WFLAGS@ @NO_ZERO_AS_NULL_POINTER_CONSTANT_FLAG@
 
 noinst_PROGRAMS = basic_test
@@ -12,19 +12,19 @@ noinst_PROGRAMS += pj_phi2_test
 noinst_PROGRAMS += proj_errno_string_test
 
 basic_test_SOURCES = basic_test.cpp main.cpp
-basic_test_LDADD = ../../src/libproj.la ../../test/googletest/libgtest.la
+basic_test_LDADD = ../../src/libproj.la @GTEST_LIBS@
 
 basic_test-check: basic_test
 	./basic_test
 
 pj_phi2_test_SOURCES = pj_phi2_test.cpp main.cpp
-pj_phi2_test_LDADD = ../../src/libproj.la ../../test/googletest/libgtest.la
+pj_phi2_test_LDADD = ../../src/libproj.la @GTEST_LIBS@
 
 pj_phi2_test-check: pj_phi2_test
 	./pj_phi2_test
 
 proj_errno_string_test_SOURCES = proj_errno_string_test.cpp main.cpp
-proj_errno_string_test_LDADD= ../../src/libproj.la ../../test/googletest/libgtest.la
+proj_errno_string_test_LDADD= ../../src/libproj.la @GTEST_LIBS@
 
 proj_errno_string_test-check: proj_errno_string_test
 	./proj_errno_string_test
-- 
2.20.1