[CMake] respect LLVMConfig.cmake's LLVM_DEFINITIONS in standalone builds (#138587)

In #138329, _GNU_SOURCE was added for Cygwin, but when building Clang
standalone against an installed LLVM this definition was not picked up,
resulting in undefined strnlen. Follow the documentation in
https://llvm.org/docs/CMake.html#embedding-llvm-in-your-project and add
the LLVM_DEFINITIONS in standalone projects' cmakes.

Author: jeremyd2019

bolt/CMakeLists.txt

@@ -46,6 +46,10 @@ if(BOLT_BUILT_STANDALONE)
   set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin)
   set(LLVM_LIBRARY_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX})
 
+  separate_arguments(LLVM_DEFINITIONS_LIST NATIVE_COMMAND ${LLVM_DEFINITIONS})
+  add_definitions(${LLVM_DEFINITIONS_LIST})
+  list(APPEND CMAKE_REQUIRED_DEFINITIONS ${LLVM_DEFINITIONS_LIST})
+
   include(AddLLVM)
   include(TableGen)
   include_directories(${LLVM_INCLUDE_DIRS})

clang/CMakeLists.txt

@@ -68,6 +68,10 @@ if(CLANG_BUILT_STANDALONE)
   option(CLANG_ENABLE_BOOTSTRAP "Generate the clang bootstrap target" OFF)
   option(LLVM_ENABLE_LIBXML2 "Use libxml2 if available." ON)
 
+  separate_arguments(LLVM_DEFINITIONS_LIST NATIVE_COMMAND ${LLVM_DEFINITIONS})
+  add_definitions(${LLVM_DEFINITIONS_LIST})
+  list(APPEND CMAKE_REQUIRED_DEFINITIONS ${LLVM_DEFINITIONS_LIST})
+
   include(AddLLVM)
   include(TableGen)
   include(HandleLLVMOptions)

flang/CMakeLists.txt

@@ -140,6 +140,11 @@ if (FLANG_STANDALONE_BUILD)
   if (NOT DEFINED LLVM_MAIN_SRC_DIR)
     set(LLVM_MAIN_SRC_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../llvm")
   endif()
+
+  separate_arguments(LLVM_DEFINITIONS_LIST NATIVE_COMMAND ${LLVM_DEFINITIONS})
+  add_definitions(${LLVM_DEFINITIONS_LIST})
+  list(APPEND CMAKE_REQUIRED_DEFINITIONS ${LLVM_DEFINITIONS_LIST})
+
   include(AddLLVM)
   include(HandleLLVMOptions)
   include(VersionFromVCS)

lld/CMakeLists.txt

@@ -39,6 +39,10 @@ if(LLD_BUILT_STANDALONE)
   set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin)
   set(LLVM_LIBRARY_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX})
 
+  separate_arguments(LLVM_DEFINITIONS_LIST NATIVE_COMMAND ${LLVM_DEFINITIONS})
+  add_definitions(${LLVM_DEFINITIONS_LIST})
+  list(APPEND CMAKE_REQUIRED_DEFINITIONS ${LLVM_DEFINITIONS_LIST})
+
   include(AddLLVM)
   include(TableGen)
   include(HandleLLVMOptions)

lldb/cmake/modules/LLDBStandalone.cmake

@@ -85,6 +85,10 @@ endif()
 # CMake modules to be in that directory as well.
 list(APPEND CMAKE_MODULE_PATH "${LLVM_DIR}")
 
+separate_arguments(LLVM_DEFINITIONS_LIST NATIVE_COMMAND ${LLVM_DEFINITIONS})
+add_definitions(${LLVM_DEFINITIONS_LIST})
+list(APPEND CMAKE_REQUIRED_DEFINITIONS ${LLVM_DEFINITIONS_LIST})
+
 include(AddLLVM)
 include(TableGen)
 include(HandleLLVMOptions)

mlir/CMakeLists.txt

@@ -21,6 +21,11 @@ set(CMAKE_CXX_STANDARD 17 CACHE STRING "C++ standard to conform to")
 if(MLIR_STANDALONE_BUILD)
   find_package(LLVM CONFIG REQUIRED)
   set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${LLVM_CMAKE_DIR})
+
+  separate_arguments(LLVM_DEFINITIONS_LIST NATIVE_COMMAND ${LLVM_DEFINITIONS})
+  add_definitions(${LLVM_DEFINITIONS_LIST})
+  list(APPEND CMAKE_REQUIRED_DEFINITIONS ${LLVM_DEFINITIONS_LIST})
+
   include(HandleLLVMOptions)
   include(AddLLVM)
   include(TableGen)

polly/CMakeLists.txt

@@ -13,6 +13,11 @@ if(POLLY_STANDALONE_BUILD)
   # Where is LLVM installed?
   find_package(LLVM CONFIG REQUIRED)
   set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${LLVM_CMAKE_DIR})
+
+  separate_arguments(LLVM_DEFINITIONS_LIST NATIVE_COMMAND ${LLVM_DEFINITIONS})
+  add_definitions(${LLVM_DEFINITIONS_LIST})
+  list(APPEND CMAKE_REQUIRED_DEFINITIONS ${LLVM_DEFINITIONS_LIST})
+
   include(HandleLLVMOptions)
   include(AddLLVM)