[CMake] Make check-lldb work with LLDB_CODESIGN_IDENTITY=''

[vsk]

Summary

On Darwin, if a test machine isn't set up for code-signing (see
docs/code-signing.txt), running check-lldb should use the system
debugserver instead of the unsigned one built in-tree. This makes it
possible to run lldb's test suite without having code-signing set up,
which is really convenient.

[aprantl]

How about printing a message (if CMAKE_HOST_APPLE) that the system debugserver is being used at configure time?

[jasonmolenda]

That's a good suggestion. We have some bots using the system debugserver -- and once in a while there's a change to both lldb and debugserver, and the bots running the older prebuilt debugserver will fail any tests for that patchset.

[vsk]

Thanks for the feedback!

-Print out the path to the debug server as a status message

[davide]

LGTM with Adrian's suggestion applied, thanks for doing this!

docs/code-signing.txt

-On MacOSX lldb needs to be code signed. The Debug, DebugClang and Release 
-builds  are set to code sign using a code signing certificate named 
-"lldb_codesign". 
+To use the in-tree debug server on macOS, lldb needs to be code signed. The
+Debug, DebugClang and Release builds are set to code sign using a code signing
+certificate named "lldb_codesign". This document explains how to set up the
+signing certificate.
+
+Note that it is possible build and use lldb on macOS without setting up code
+signing by using the system's debug server. To configure lldb in this way with
+cmake, specify -DLLDB_CODESIGN_IDENTITY=''.
 
 If you have re-installed a new OS, please delete all old lldb_codesign items
 from your keychain. There will be a code signing certification and a public
 and private key. Reboot after deleting them. You will also need to delete and
 build folders that contained old signed items. The darwin kernel will cache 
 code signing using the executable's file system node, so you will need to
 delete the file so the kernel clears its cache.
 

test/CMakeLists.txt

if (CMAKE_SYSTEM_NAME MATCHES "Darwin")
   list(APPEND LLDB_TEST_DEPS darwin-debug)
 endif()
 
 if(TARGET lldb-server)
   list(APPEND LLDB_TEST_DEPS lldb-server)
 endif()
   
 if(TARGET debugserver)
+  if(NOT CMAKE_HOST_APPLE OR LLDB_CODESIGN_IDENTITY)
     list(APPEND LLDB_TEST_DEPS debugserver)
   endif()
+endif()
 
 if(TARGET lldb-mi)
   list(APPEND LLDB_TEST_DEPS lldb-mi)
 endif()
 
 # The default architecture with which to compile test executables is the default LLVM target
 # architecture, which itself defaults to the host architecture.
 string(TOLOWER "${LLVM_TARGET_ARCH}" LLDB_DEFAULT_TEST_ARCH)

 endif()
 
 if (NOT ${CMAKE_SYSTEM_NAME} MATCHES "Windows|Darwin")
   list(APPEND LLDB_TEST_COMMON_ARGS
     --env ARCHIVER=${CMAKE_AR} --env OBJCOPY=${CMAKE_OBJCOPY})
 endif()
 
 if(CMAKE_HOST_APPLE)
-  list(APPEND LLDB_TEST_COMMON_ARGS --server $<TARGET_FILE:debugserver>)
+  if(LLDB_CODESIGN_IDENTITY)
+    set(DEBUGSERVER_PATH $<TARGET_FILE:debugserver>)
+  else()
+    execute_process(
+      COMMAND xcode-select -p
+      OUTPUT_VARIABLE XCODE_DEV_DIR)
+    string(STRIP ${XCODE_DEV_DIR} XCODE_DEV_DIR)
+    set(DEBUGSERVER_PATH
+      "${XCODE_DEV_DIR}/../SharedFrameworks/LLDB.framework/Resources/debugserver")
+  endif()
+  message(STATUS "Path to the lldb debugserver: ${DEBUGSERVER_PATH}")
+  list(APPEND LLDB_TEST_COMMON_ARGS --server ${DEBUGSERVER_PATH})
 endif()
 
 set(LLDB_DOTEST_ARGS ${LLDB_TEST_COMMON_ARGS};${LLDB_TEST_USER_ARGS})
 
 add_python_test_target(check-lldb-single
   ${LLDB_SOURCE_DIR}/test/dotest.py
   "--no-multiprocess;${LLDB_DOTEST_ARGS}"
   "Testing LLDB with args: ${LLDB_DOTEST_ARGS}"