CMake - introduce dependency on libunwind

Author: SiskaPavel

cmake/dependencies.cmake

@@ -3,3 +3,4 @@ find_package(PkgConfig REQUIRED)
 
 find_package(Threads REQUIRED)
 find_package(Atomic REQUIRED)
+find_package(Unwind REQUIRED)

cmake/modules/FindUnwind.cmake

@@ -0,0 +1,45 @@
+# Find unwind library
+# Once done this will define
+#
+#  UNWIND_FOUND - system has libunwind
+#  unwind::unwind - cmake target 
+
+find_package(PkgConfig QUIET)
+if (PKG_CONFIG_FOUND)
+	pkg_check_modules(PC_UNWIND QUIET libunwind)
+endif()
+
+find_path (UNWIND_INCLUDE_DIR 
+  NAMES unwind.h libunwind.h
+  HINTS ${UNWIND_ROOT} ${PC_UNWIND_INCLUDEDIR} ${PC_UNWIND_INCLUDE_DIRS}
+  PATH_SUFFIXES ${CMAKE_INSTALL_LIBDIR}
+)
+
+find_library (UNWIND_LIBRARY 
+  NAMES unwind
+  HINTS ${UNWIND_ROOT} ${PC_UNWIND_LIBDIR} ${PC_UNWIND_LIBRARY_DIRS}
+  PATH_SUFFIXES ${CMAKE_INSTALL_LIBDIR}  
+)
+
+mark_as_advanced (UNWIND_INCLUDE_DIR UNWIND_LIBRARY)
+
+include (FindPackageHandleStandardArgs)
+# handle the QUIETLY and REQUIRED arguments and set Unwind_FOUND to TRUE
+# if all listed variables are TRUE
+find_package_handle_standard_args (Unwind
+  REQUIRED_VARS UNWIND_INCLUDE_DIR UNWIND_LIBRARY
+)
+
+if (UNWIND_FOUND AND NOT TARGET unwind::unwind)
+  add_library(unwind::unwind STATIC IMPORTED)
+  set_target_properties(unwind::unwind PROPERTIES
+    IMPORTED_LOCATION "${UNWIND_LIBRARY}"
+    INTERFACE_INCLUDE_DIRECTORIES "${UNWIND_INCLUDE_DIR}")
+  target_compile_definitions(unwind::unwind INTERFACE UNWIND_FOUND)
+else()
+  message(WARNING "Notice: UNWIND not found, no unwind support")
+  add_library(unwind::unwind INTERFACE IMPORTED)
+endif()
+
+unset(UNWIND_INCLUDE_DIR)
+unset(UNWIND_LIBRARY)