[lldb/CMake] Use LLDB's autodetection logic for libxml2

[JDevlieghere]

Summary

Libxml2 is already an optional dependency. It should use the same infrastructure as the other dependencies.

[labath]

lldb/cmake/modules/FindLibXml28.cmake

14 ↗

(On Diff #236406)

Why is this under if(APPLE) ?

[kwk]

lldb/cmake/modules/FindLibXml28.cmake

14 ↗

(On Diff #236406)

To me this looks as if this module file FileLibXml28.cmake is only relevant for Apple. In line 10 it falls back to the standard CMake find-module file (find_package(LibXml2 QUIET)). Is this correct?

[JDevlieghere]

lldb/cmake/modules/FindLibXml28.cmake

14 ↗

(On Diff #236406)

I'm not sure, I just kept the old behavior. I'm pretty sure it doesn't matter. Do you prefer to make it unconditional or just remove it altogether?

[labath]

lldb/cmake/modules/FindLibXml28.cmake

14 ↗

(On Diff #236406)

Ah, right, I think I now see where this is coming from. I don't think it makes sense to keep this if xml is disabled then linking against it is useless. Ideally, I'd just remove it...

[compnerd]

lldb/cmake/modules/FindLibXml28.cmake

14 ↗

(On Diff #236406)

Why the custom module for this? Why not use find_package(LibXml2 2.8 QUIET) and ensure that libxml2 is >= 2.8?

[JDevlieghere]

lldb/cmake/modules/FindLibXml28.cmake

14 ↗

(On Diff #236406)

Right, with the special if(APPLE) logic gone there there's no good reason to have a custom module anymore.

[JDevlieghere]

Typo

[labath]

cool

lldb/cmake/modules/LLDBConfig.cmake

 
 set(LLDB_LINKER_SUPPORTS_GROUPS OFF)
 if (LLVM_COMPILER_IS_GCC_COMPATIBLE AND NOT "${CMAKE_SYSTEM_NAME}" MATCHES "Darwin")
   # The Darwin linker doesn't understand --start-group/--end-group.
   set(LLDB_LINKER_SUPPORTS_GROUPS ON)
 endif()
 
 macro(add_optional_dependency variable description package found)
+  cmake_parse_arguments(ARG
+    ""
+    "VERSION"
+    ""
+    ${ARGN})
+
   set(${variable} "Auto" CACHE STRING "${description} On, Off or Auto (default)")
   string(TOUPPER "${${variable}}" ${variable})
 
   if("${${variable}}" STREQUAL "AUTO")
     set(find_package TRUE)
     set(maybe_required)
   elseif(${${variable}})
     set(find_package TRUE)
     set(maybe_required REQUIRED)
   else()
     set(find_package FALSE)
     set(${variable} FALSE)
   endif()
 
   if(${find_package})
-    find_package(${package} ${maybe_required})
+    find_package(${package} ${ARG_VERSION} ${maybe_required})
     set(${variable} "${${found}}")
   endif()
 
   message(STATUS "${description}: ${${variable}}")
 endmacro()
 
 add_optional_dependency(LLDB_ENABLE_LIBEDIT "Enable editline support in LLDB" LibEdit LibEdit_FOUND)
 add_optional_dependency(LLDB_ENABLE_CURSES "Enable curses support in LLDB" CursesAndPanel CURSESANDPANEL_FOUND)
 add_optional_dependency(LLDB_ENABLE_LZMA "Enable LZMA compression support in LLDB" LibLZMA LIBLZMA_FOUND)
 add_optional_dependency(LLDB_ENABLE_LUA "Enable Lua scripting support in LLDB" Lua LUA_FOUND)
 add_optional_dependency(LLDB_ENABLE_PYTHON "Enable Python scripting support in LLDB" PythonInterpAndLibs PYTHONINTERPANDLIBS_FOUND)
+add_optional_dependency(LLDB_ENABLE_LIBXML2 "Enable Libxml 2 support in LLDB" LibXml2 LIBXML2_FOUND VERSION 2.8)
 
 option(LLDB_RELOCATABLE_PYTHON "Use the PYTHONHOME environment variable to locate Python." OFF)
 option(LLDB_USE_SYSTEM_SIX "Use six.py shipped with system and do not install a copy of it" OFF)
 option(LLDB_USE_ENTITLEMENTS "When codesigning, use entitlements if available" ON)
 option(LLDB_BUILD_FRAMEWORK "Build LLDB.framework (Darwin only)" OFF)
 option(LLDB_NO_INSTALL_DEFAULT_RPATH "Disable default RPATH settings in binaries" OFF)
 option(LLDB_USE_SYSTEM_DEBUGSERVER "Use the system's debugserver for testing (Darwin only)." OFF)
 option(LLDB_SKIP_STRIP "Whether to skip stripping of binaries when installing lldb." OFF)

 endif()
 set(LLDB_VERSION "${LLDB_VERSION_MAJOR}.${LLDB_VERSION_MINOR}.${LLDB_VERSION_PATCH}${LLDB_VERSION_SUFFIX}")
 message(STATUS "LLDB version: ${LLDB_VERSION}")
 
 if (LLDB_ENABLE_LZMA)
   include_directories(${LIBLZMA_INCLUDE_DIRS})
 endif()
 
+if (LLDB_ENABLE_LIBXML2)
+  list(APPEND system_libs ${LIBXML2_LIBRARIES})
+  include_directories(${LIBXML2_INCLUDE_DIR})
+endif()
+
 include_directories(BEFORE
   ${CMAKE_CURRENT_BINARY_DIR}/include
   ${CMAKE_CURRENT_SOURCE_DIR}/include
   )
 
 if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   install(DIRECTORY include/
     COMPONENT lldb-headers
if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   set_target_properties(lldb-headers PROPERTIES FOLDER "lldb misc")
 
   if (NOT CMAKE_CONFIGURATION_TYPES)
     add_llvm_install_targets(install-lldb-headers
                              COMPONENT lldb-headers)
   endif()
 endif()
 
-if (NOT LIBXML2_FOUND)
-  find_package(LibXml2)
-endif()
-
-# Find libraries or frameworks that may be needed
+# Find Apple-specific libraries or frameworks that may be needed.
 if (APPLE)
   if(NOT IOS)
     find_library(CARBON_LIBRARY Carbon)
     find_library(CORE_SERVICES_LIBRARY CoreServices)
   endif()
   find_library(FOUNDATION_LIBRARY Foundation)
   find_library(CORE_FOUNDATION_LIBRARY CoreFoundation)
   find_library(SECURITY_LIBRARY Security)
-  set(LLDB_ENABLE_LIBXML2 ON)
-  list(APPEND system_libs xml2
+  list(APPEND system_libs
        ${FOUNDATION_LIBRARY}
        ${CORE_FOUNDATION_LIBRARY}
        ${CORE_SERVICES_LIBRARY}
        ${SECURITY_LIBRARY}
        ${DEBUG_SYMBOLS_LIBRARY})
   include_directories(${LIBXML2_INCLUDE_DIR})
-elseif(LIBXML2_FOUND AND LIBXML2_VERSION_STRING VERSION_GREATER 2.8)
-  set(LLDB_ENABLE_LIBXML2 ON)
-  list(APPEND system_libs ${LIBXML2_LIBRARIES})
-  include_directories(${LIBXML2_INCLUDE_DIR})
 endif()
 
 if( WIN32 AND NOT CYGWIN )
   set(PURE_WINDOWS 1)
 endif()
 
 if(NOT PURE_WINDOWS)
   set(CMAKE_THREAD_PREFER_PTHREAD TRUE)

lldb/docs/resources/build.rst

 | Feature           | Description                                          | CMake Flag               |
 +===================+======================================================+==========================+
 | Editline          | Generic line editing, history, Emacs and Vi bindings | ``LLDB_ENABLE_LIBEDIT``  |
 +-------------------+------------------------------------------------------+--------------------------+
 | Curses            | Text user interface                                  | ``LLDB_ENABLE_CURSES``   |
 +-------------------+------------------------------------------------------+--------------------------+
 | LZMA              | Lossless data compression                            | ``LLDB_ENABLE_LZMA``     |
 +-------------------+------------------------------------------------------+--------------------------+
+| Libxml2           | XML                                                  | ``LLDB_ENABLE_LIBXML2``  |
++-------------------+------------------------------------------------------+--------------------------+
 | Python            | Python scripting                                     | ``LLDB_ENABLE_PYTHON``   |
 +-------------------+------------------------------------------------------+--------------------------+
 | Lua               | Lua scripting                                        | ``LLDB_ENABLE_LUA``      |
 +-------------------+------------------------------------------------------+--------------------------+
 
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