Improve dependency handling for libunwind and installation relocatability (#314)

Fixes #287

Author: jeremy-rifkin

CMakeLists.txt

@@ -474,39 +474,9 @@ if(CPPTRACE_UNWIND_WITH_UNWIND)
 endif()
 
 if(CPPTRACE_UNWIND_WITH_LIBUNWIND)
-  find_package(PkgConfig)
-  if(PkgConfig_FOUND)
-    pkg_check_modules(LIBUNWIND QUIET libunwind)
-    if(LIBUNWIND_FOUND)
-      target_compile_options(${target_name} PRIVATE ${LIBUNWIND_CFLAGS_OTHER})
-      target_include_directories(${target_name} PRIVATE ${LIBUNWIND_INCLUDE_DIRS})
-      target_link_libraries(${target_name} PRIVATE ${LIBUNWIND_LDFLAGS})
-    endif()
-  endif()
-  if(NOT LIBUNWIND_FOUND)
-    if (NOT APPLE)
-      # set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIB64_PATHS ON)
-      # set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIB32_PATHS ON)
-      find_path(LIBUNWIND_INCLUDE_DIRS NAMES "libunwind.h")
-      find_library(LIBUNWIND NAMES unwind libunwind libunwind8 libunwind.so.8 REQUIRED PATHS "/usr/lib/x86_64-linux-gnu/")
-      if(LIBUNWIND)
-        set(LIBUNWIND_FOUND TRUE)
-      endif()
-      if(NOT LIBUNWIND_FOUND)
-        # message(FATAL_ERROR "Unable to locate libunwind")
-        # Try to link with it if it's where it should be
-        # This path can be entered if libunwind was installed via the system package manager, sometimes. I probably messed
-        # up the find_library above.
-        set(LIBUNWIND_LDFLAGS "-lunwind")
-      endif()
-      if(NOT LIBUNWIND_LDFLAGS)
-        set(LIBUNWIND_LDFLAGS "${LIBUNWIND}")
-      endif()
-      target_compile_options(${target_name} PRIVATE ${LIBUNWIND_CFLAGS_OTHER})
-      target_include_directories(${target_name} PRIVATE ${LIBUNWIND_INCLUDE_DIRS})
-      target_link_libraries(${target_name} PRIVATE ${LIBUNWIND_LDFLAGS})
-    endif()
-  endif()
+  list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
+  find_package(Libunwind REQUIRED)
+  target_link_libraries(${target_name} PRIVATE Libunwind::Libunwind)
   target_compile_definitions(${target_name} PRIVATE CPPTRACE_UNWIND_WITH_LIBUNWIND UNW_LOCAL_ONLY)
 endif()
 

cmake/FindLibunwind.cmake

@@ -0,0 +1,40 @@
+# Find module for libunwind, providing Libunwind::Libunwind
+
+if(APPLE)
+  # On Apple, libunwind is built into the system. Headers are available via the SDK, no library is needed.
+  set(Libunwind_FOUND TRUE)
+  if(NOT TARGET Libunwind::Libunwind)
+    add_library(Libunwind::Libunwind INTERFACE IMPORTED)
+  endif()
+else()
+  # Use pkg-config for hints
+  find_package(PkgConfig QUIET)
+  if(PkgConfig_FOUND)
+    pkg_check_modules(_LIBUNWIND QUIET libunwind)
+  endif()
+
+  find_path(Libunwind_INCLUDE_DIR NAMES libunwind.h HINTS ${_LIBUNWIND_INCLUDE_DIRS})
+  find_library(Libunwind_LIBRARY NAMES unwind libunwind HINTS ${_LIBUNWIND_LIBRARY_DIRS})
+
+  include(FindPackageHandleStandardArgs)
+  find_package_handle_standard_args(
+    Libunwind DEFAULT_MSG
+    Libunwind_LIBRARY Libunwind_INCLUDE_DIR
+  )
+
+  if(Libunwind_FOUND)
+    message(STATUS "Found Libunwind: ${Libunwind_LIBRARY}")
+  endif()
+
+  mark_as_advanced(Libunwind_INCLUDE_DIR Libunwind_LIBRARY)
+
+  if(Libunwind_FOUND AND NOT TARGET Libunwind::Libunwind)
+    add_library(Libunwind::Libunwind UNKNOWN IMPORTED)
+    set_target_properties(
+      Libunwind::Libunwind
+      PROPERTIES
+      IMPORTED_LOCATION "${Libunwind_LIBRARY}"
+      INTERFACE_INCLUDE_DIRECTORIES "${Libunwind_INCLUDE_DIR}"
+    )
+  endif()
+endif()

cmake/InstallRules.cmake

@@ -81,11 +81,13 @@ if(CPPTRACE_PROVIDE_EXPORT_SET)
   )
 endif()
 
-# Findzstd.cmake
+# Find modules for dependencies
 # vcpkg doesn't like anything being put in share/, which is where this goes apparently on their setup
 if(NOT CPPTRACE_VCPKG)
   install(
-    FILES "${PROJECT_SOURCE_DIR}/cmake/Findzstd.cmake"
+    FILES
+    "${PROJECT_SOURCE_DIR}/cmake/Findzstd.cmake"
+    "${PROJECT_SOURCE_DIR}/cmake/FindLibunwind.cmake"
     DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${package_name}"
   )
 endif()

cmake/in/cpptrace-config-cmake.in

@@ -2,23 +2,28 @@
 @PACKAGE_INIT@
 
 # Dependencies
+include(CMakeFindDependencyMacro)
+set(CMAKE_MODULE_PATH_OLD "${CMAKE_MODULE_PATH}")
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}")
+
 if(@CPPTRACE_GET_SYMBOLS_WITH_LIBDWARF@)
-  include(CMakeFindDependencyMacro)
-  # we don't go the Findzstd.cmake route on vcpkg
   if(@CPPTRACE_VCPKG@)
     find_dependency(zstd CONFIG REQUIRED)
   else()
-    set(CMAKE_MODULE_PATH_OLD "${CMAKE_MODULE_PATH}")
-    set(CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH};${CMAKE_CURRENT_LIST_DIR}")
     find_dependency(zstd)
-    set(CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH_OLD}")
-    unset(CMAKE_MODULE_PATH_OLD)
   endif()
   if(NOT @CPPTRACE_FIND_LIBDWARF_WITH_PKGCONFIG@)
     find_dependency(libdwarf REQUIRED)
   endif()
 endif()
 
+if(@CPPTRACE_UNWIND_WITH_LIBUNWIND@)
+  find_dependency(Libunwind)
+endif()
+
+set(CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH_OLD}")
+unset(CMAKE_MODULE_PATH_OLD)
+
 # We cannot modify an existing IMPORT target
 if(NOT TARGET cpptrace::cpptrace)