Add build-time option to set gcc C++ ABI (ported from OIIO) (#995)

Makefile

@@ -187,6 +187,10 @@ ifneq (${USE_LIBCPLUSPLUS},)
 MY_CMAKE_FLAGS += -DUSE_LIBCPLUSPLUS:BOOL=${USE_LIBCPLUSPLUS}
 endif
 
+ifneq (${GLIBCXX_USE_CXX11_ABI},)
+MY_CMAKE_FLAGS += -DGLIBCXX_USE_CXX11_ABI=${GLIBCXX_USE_CXX11_ABI}
+endif
+
 ifneq (${EXTRA_CPP_ARGS},)
 MY_CMAKE_FLAGS += -DEXTRA_CPP_ARGS:STRING="${EXTRA_CPP_ARGS}"
 endif
@@ -373,6 +377,7 @@ help:
 	@echo "      MYCC=xx MYCXX=yy         Use custom compilers"
 	@echo "      USE_CPP=14               Compile in C++14 mode (default is C++11)"
 	@echo "      USE_LIBCPLUSPLUS=1       Use clang libc++"
+	@echo "      GLIBCXX_USE_CXX11_ABI=1  For gcc, use the new string ABI"
 	@echo "      EXTRA_CPP_ARGS=          Additional args to the C++ command"
 	@echo "      USE_NINJA=1              Set up Ninja build (instead of make)"
 	@echo "      USE_CCACHE=0             Disable ccache (even if available)"

src/cmake/compiler.cmake

@@ -21,6 +21,7 @@ option (CLANG_TIDY "Enable clang-tidy" OFF)
 set (CLANG_TIDY_CHECKS "-*" CACHE STRING "clang-tidy checks to perform")
 set (CLANG_TIDY_ARGS "" CACHE STRING "clang-tidy args")
 option (CLANG_TIDY_FIX "Have clang-tidy fix source" OFF)
+set (GLIBCXX_USE_CXX11_ABI "" CACHE STRING "For gcc, use the new C++11 library ABI (0|1)")
 
 
 # Figure out which compiler we're using
@@ -196,6 +197,18 @@ if (USE_LIBCPLUSPLUS AND CMAKE_COMPILER_IS_CLANG)
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")
 endif ()
 
+# GCC 5+: honor build-time option for whether or not to use new string ABI.
+# FIXME: In theory, this should also be needed for clang, if compiling with
+# the gcc libstdc++ toolchain. In practice, I could not get things to build
+# with clang properly when using this option, and I haven't yet seen a case
+# where it's needed. We can return to this and fix for clang if it becomes a
+# legit problem later.
+if (CMAKE_COMPILER_IS_GNUCC AND NOT ${GCC_VERSION} VERSION_LESS 5.0)
+    if (NOT ${GLIBCXX_USE_CXX11_ABI} STREQUAL "")
+        add_definitions ("-D_GLIBCXX_USE_CXX11_ABI=${GLIBCXX_USE_CXX11_ABI}")
+    endif ()
+endif ()
+
 
 # SIMD and machine architecture options
 set (SIMD_COMPILE_FLAGS "")