[CMake] Add compile-time check that libtvm_runtime.so has no undefine…

…d symbols.

If libtvm_runtime.so erroneously requires definitions that are only
present in libtvm.so, the -Wl,-z,defs flag forces them to be
compile-time errors rather than runtime, and would be caught by the
CI.

CMakeLists.txt

@@ -165,6 +165,15 @@ else(MSVC)
     set(CMAKE_CXX_FLAGS "-faligned-new ${CMAKE_CXX_FLAGS}")
   endif()
 
+  # ld option to warn if symbols are undefined (e.g. libtvm_runtime.so
+  # using symbols only present in libtvm.so).  Not needed for MSVC,
+  # since this is already the default there.
+  if(CMAKE_SYSTEM_NAME EQUAL "Darwin")
+    set(CMAKE_SHARED_LINKER_FLAGS "-Wl,-undefined,error ${CMAKE_SHARED_LINKER_FLAGS}")
+  else()
+    set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--no-undefined ${CMAKE_SHARED_LINKER_FLAGS}")
+  endif()
+
   # Detect if we're compiling for Hexagon.
   set(TEST_FOR_HEXAGON_CXX
       "#ifndef __hexagon__"