For some reasons, building compiler-rt with the github method is changing some options. It seems that it adds -m elf_i386 to the linker. Causing a build failure. See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=942864 https://bugs.llvm.org/show_bug.cgi?id=43677 trying to remove the flag in compiler-rt-fuzzer-remove-elf_i386.diff

debian/changelog

@@ -4,6 +4,12 @@ llvm-toolchain-9 (1:9.0.0-2) unstable; urgency=medium
     So, add to PROJECTS only when enabled
   * clang: Force the installation of libclang-cpp with the exact same version
     and remove libclang as dep
+  * For some reasons, building compiler-rt with the github method
+    is changing some options. It seems that it adds -m elf_i386 to the
+    linker. Causing a build failure.
+    See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=942864
+    https://bugs.llvm.org/show_bug.cgi?id=43677
+    trying to remove the flag in compiler-rt-fuzzer-remove-elf_i386.diff
 
  -- Sylvestre Ledru <sylvestre@debian.org>  Sun, 20 Oct 2019 17:27:50 +0200
 

debian/patches/compiler-rt-fuzzer-remove-elf_i386.diff

@@ -0,0 +1,13 @@
+Index: llvm-toolchain-snapshot-10~+201910241319490700d0bd3fc88be/compiler-rt/lib/fuzzer/CMakeLists.txt
+===================================================================
+--- llvm-toolchain-snapshot-10~+201910241319490700d0bd3fc88be.orig/compiler-rt/lib/fuzzer/CMakeLists.txt
++++ llvm-toolchain-snapshot-10~+201910241319490700d0bd3fc88be/compiler-rt/lib/fuzzer/CMakeLists.txt
+@@ -122,7 +122,7 @@ if(OS_NAME MATCHES "Linux|Fuchsia" AND
+    COMPILER_RT_LIBCXXABI_PATH)
+   macro(partially_link_libcxx name dir arch)
+     if(${arch} MATCHES "i386")
+-      set(EMULATION_ARGUMENT "-m" "elf_i386")
++      set(EMULATION_ARGUMENT "")
+     else()
+       set(EMULATION_ARGUMENT "")
+     endif()

debian/patches/series

@@ -132,3 +132,4 @@ clang-riscv64-rv64gc.diff
 #try-to-unbreak-thinlto.diff
 D67877.patch
 disable-lit-cpuid-install.diff
+compiler-rt-fuzzer-remove-elf_i386.diff