* Fix the FTBFS because of -gsplit-dwarf:

- Only enable it on archs which needs it
  - Only enable it when gcc supports it correctly

debian/changelog

@@ -1,3 +1,11 @@
+llvm-toolchain-5.0 (1:5.0~+rc4-2) UNRELEASED; urgency=medium
+
+  * Fix the FTBFS because of -gsplit-dwarf:
+    - Only enable it on archs which needs it
+    - Only enable it when gcc supports it correctly
+
+ -- Sylvestre Ledru <sylvestre@debian.org>  Thu, 31 Aug 2017 19:14:45 +0200
+
 llvm-toolchain-5.0 (1:5.0~+rc4-1) unstable; urgency=medium
 
   * New testing release

debian/rules

@@ -34,15 +34,21 @@ ifneq (,$(filter $(DEB_HOST_ARCH),powerpc powerpcspe))
 LDFLAGS_EXTRA += -latomic
 endif
 
+ENABLE_SPLIT_DWARF_ARCHS := armel armhf i386 mips powerpc
+# Only enable gsplit dwarf on archs which needs it
+ifneq (,$(filter $(DEB_HOST_ARCH),$(ENABLE_SPLIT_DWARF_ARCHS)))
 ifeq ($(shell dpkg --compare-versions $(shell dpkg-query -W -f '$${Version}' binutils) ge 2.22.52.0.4 ; echo $$?),0)
 # when using -gsplit-dwarf, it will requires extract-dwo which doesn't exist on precise:
 # More: https://llvm.org/bugs/show_bug.cgi?id=28841
 ifeq ($(shell dpkg --compare-versions $(shell dpkg-query -W -f '$${Version}' g++-$(GCC_VERSION)) lt 7.1.0-7~ ; echo $$?),0)
-# Do not pass -gsplit-dwarf with gcc 7. This is causing some linking issues
-# More: https://bugs.llvm.org/show_bug.cgi?id=34140
+ifeq ($(shell dpkg --compare-versions $(shell dpkg-query -W -f '$${Version}' g++-$(GCC_VERSION)) ge 7.2.0-2 ; echo $$?),0)
+# Only pass -gsplit-dwarf with working version of gcc 7
+# More: https://bugs.llvm.org/show_bug.cgi?id=34140 & https://bugs.debian.org/873609
 CXXFLAGS_EXTRA += -gsplit-dwarf
-endif
-endif
+endif # > 7.2.0-2
+endif # < gcc 7
+endif # binutils
+endif # archs
 
 
 ifeq ($(shell dpkg --compare-versions $(shell dpkg-query -W -f '$${Version}' g++-$(GCC_VERSION)) lt 4.7.2-10~ ; echo $$?),0)