only use symbolizer if libunwind is found

Summary: folly/experimental/symbolizer requires libunwind. Do not enable it unless libunwind is available.

Reviewed By: yfeldblum, luciang

Differential Revision: D22964401

fbshipit-source-id: d71991346927fbf18167637770b2143c03b16476

CMake/folly-deps.cmake

@@ -145,16 +145,18 @@ if (PYTHON_EXTENSIONS)
   find_package(Cython 0.26 REQUIRED)
 endif ()
 
+find_package(LibUnwind)
+list(APPEND FOLLY_LINK_LIBRARIES ${LIBUNWIND_LIBRARIES})
+list(APPEND FOLLY_INCLUDE_DIRECTORIES ${LIBUNWIND_INCLUDE_DIRS})
+
 set(FOLLY_USE_SYMBOLIZER OFF)
-CHECK_INCLUDE_FILE_CXX(elf.h FOLLY_HAVE_ELF_H)
-find_library(UNWIND_LIBRARIES NAMES unwind)
-if (UNWIND_LIBRARIES)
-  list(APPEND FOLLY_LINK_LIBRARIES ${UNWIND_LIBRARIES})
+CHECK_INCLUDE_FILE_CXX(elf.h FOLLY_HAVE_ELF)
+if (LIBUNWIND_FOUND)
   list(APPEND CMAKE_REQUIRED_LIBRARIES ${UNWIND_LIBRARIES})
 endif()
 find_package(Backtrace)
 set(FOLLY_HAVE_BACKTRACE ${Backtrace_FOUND})
-if (FOLLY_HAVE_ELF_H AND FOLLY_HAVE_BACKTRACE AND LIBDWARF_FOUND)
+if (FOLLY_HAVE_ELF AND FOLLY_HAVE_BACKTRACE AND LIBUNWIND_FOUND AND LIBDWARF_FOUND)
   set(FOLLY_USE_SYMBOLIZER ON)
 endif()
 message(STATUS "Setting FOLLY_USE_SYMBOLIZER: ${FOLLY_USE_SYMBOLIZER}")
@@ -241,4 +243,3 @@ target_link_libraries(folly_deps INTERFACE
   ${FOLLY_SHINY_DEPENDENCIES}
   ${FOLLY_ASAN_FLAGS}
 )
-

build/fbcode_builder/CMake/FindLibUnwind.cmake

+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+find_path(LIBUNWIND_INCLUDE_DIR NAMES libunwind.h)
+mark_as_advanced(LIBUNWIND_INCLUDE_DIR)
+
+find_library(LIBUNWIND_LIBRARY NAMES unwind)
+mark_as_advanced(LIBUNWIND_LIBRARY)
+
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(
+  LIBUNWIND
+  REQUIRED_VARS LIBUNWIND_LIBRARY LIBUNWIND_INCLUDE_DIR)
+
+if(LIBUNWIND_FOUND)
+  set(LIBUNWIND_LIBRARIES ${LIBUNWIND_LIBRARY})
+  set(LIBUNWIND_INCLUDE_DIRS ${LIBUNWIND_INCLUDE_DIR})
+endif()