Fallback to Boost.Regex if <regex> is broken

A large number of g++ versions ship a <regex> that declares all of the
required functions, but don't actually implement them, making using them
result in a linker error.

Fallback to Boost.Regex if the host C++11 <regex> implementation is
broken; the interface is the same anyway, only differing in the
containing namespace.

Unfortunately, Boost.Regex is not a header-only library, but this is not
a big deal because all major Linux distributions ship it, and Visual
Studio implements <regex> since 2010 (the oldest version we still
support).

CMakeLists.txt

@@ -1,7 +1,7 @@
 # OpenClonk, http://www.openclonk.org
 #
 # Copyright (c) 2009-2011  Günther Brammer
-# Copyright (c) 2009-2012  Nicolas Hake
+# Copyright (c) 2009-2013  Nicolas Hake
 # Copyright (c) 2009  David Dormagen
 # Copyright (c) 2009-2012  Armin Burgmeier
 # Copyright (c) 2009-2010  Sven Eberhardt
@@ -106,6 +106,14 @@ CHECK_CXX_SOURCE_COMPILES("int main() { void *d = nullptr; }" HAVE_NULLPTR)
 CHECK_CXX_SOURCE_COMPILES("int main() { static_assert(true, \"\"); }" HAVE_STATIC_ASSERT)
 set(CMAKE_REQUIRED_FLAGS "${SAFE_CMAKE_REQUIRED_FLAGS}")
 
+# g++'s libstdc++ doesn't properly support <regex> until 4.8.1 (maybe later?).
+# They ship a header that declares functions, but they don't ship an
+# implementation for some things (like std::regex_iterator).
+# This needs to test *linking*, not compilation; cmake does both at the same
+# time, so the test below works.
+CHECK_CXX_SOURCE_COMPILES("#include <regex>\nint main() { std::cregex_iterator ri; }" HAVE_WORKING_REGEX)
+CMAKE_DEPENDENT_OPTION(USE_BOOST_REGEX "Use Boost.Regex even if the C++ runtime has a working implementation of <regex>" OFF "HAVE_WORKING_REGEX" ON)
+
 if(MSVC_VERSION GREATER 1499)
 		list(APPEND OC_CXX_FLAGS /MP)
 		list(REMOVE_ITEM OC_CXX_FLAGS_DEBUG /Gm)
@@ -842,12 +850,8 @@ include(FindPNG)
 include(FindZLIB)
 include_directories(${JPEG_INCLUDE_DIR} ${PNG_INCLUDE_DIR} ${ZLIB_INCLUDE_DIR})
 
-find_package("Boost" 1.40.0)
-if(NOT Boost_INCLUDE_DIR)
-	message(SEND_ERROR "Could not find the Boost C++ Libraries")
-else()
-	include_directories(SYSTEM ${Boost_INCLUDE_DIR})
-endif()
+find_package("Boost" 1.40.0 REQUIRED)
+include_directories(SYSTEM ${Boost_INCLUDE_DIR})
 
 include(FindThreads)
 if(NOT WIN32)
@@ -1423,6 +1427,15 @@ if(HAVE_UPNP)
 	target_link_libraries(openclonk ${UPNP_LIBRARIES})
 endif()
 
+if(USE_BOOST_REGEX)
+	SET(Boost_USE_STATIC_LIBS ON)
+	find_package(Boost 1.40.0 REQUIRED COMPONENTS regex)
+	# Disable automatic linking, we'll do it ourselves
+	add_definitions(-DBOOST_REGEX_NO_LIB)
+	target_link_libraries(libc4script ${Boost_REGEX_LIBRARY})
+	target_link_libraries(c4group ${Boost_REGEX_LIBRARY})
+endif()
+
 add_subdirectory(tests EXCLUDE_FROM_ALL)
 
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/config.h.cmake ${CMAKE_CURRENT_BINARY_DIR}/config.h)

config.h.cmake

@@ -181,6 +181,9 @@
 /* Developer mode */
 #cmakedefine WITH_DEVELOPER_MODE 1
 
+/* Define to 1 if you want to use Boost.Regex instead of <regex>. */
+#cmakedefine USE_BOOST_REGEX 1
+
 /* Glib */
 #cmakedefine WITH_GLIB 1
 

src/c4group/C4Language.cpp

@@ -38,7 +38,14 @@
 #include <C4Config.h>
 #include <C4Game.h>
 
-#include <regex>
+#ifdef USE_BOOST_REGEX
+#	undef new
+#	include <boost/regex.hpp>
+	namespace re = boost;
+#else
+#	include <regex>
+	namespace re = std;
+#endif
 
 #ifdef HAVE_ICONV
 #ifdef HAVE_LANGINFO_H
@@ -390,7 +397,7 @@ namespace
 {
 	std::string GetResStr(const char *id, const char *stringtbl)
 	{
-		static std::regex line_pattern("^([^=]+)=(.*)\\r?$", std::regex_constants::optimize);
+		static re::regex line_pattern("^([^=]+)=(.*)\\r?$", re::regex_constants::optimize);
 		assert(stringtbl);
 		if (!stringtbl)
 		{
@@ -401,7 +408,7 @@ namespace
 		const char *begin = stringtbl;
 		const char *end = begin + std::char_traits<char>::length(begin);
 
-		for (auto it = std::cregex_iterator(begin, end, line_pattern); it != std::cregex_iterator(); ++it)
+		for (auto it = re::cregex_iterator(begin, end, line_pattern); it != re::cregex_iterator(); ++it)
 		{
 			assert(it->size() == 3);
 			if (it->size() != 3)