From ba4bd3f46e97b5637b16a0fa74b064fb3e6db8ff Mon Sep 17 00:00:00 2001
From: jeremyd2019 <github@jdrake.com>
Date: Wed, 21 May 2025 22:14:13 -0700
Subject: [PATCH] [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.
---
 bolt/CMakeLists.txt                     | 4 ++++
 clang/CMakeLists.txt                    | 4 ++++
 flang/CMakeLists.txt                    | 5 +++++
 lld/CMakeLists.txt                      | 4 ++++
 lldb/cmake/modules/LLDBStandalone.cmake | 4 ++++
 mlir/CMakeLists.txt                     | 5 +++++
 polly/CMakeLists.txt                    | 5 +++++
 7 files changed, 31 insertions(+)

diff --git a/bolt/CMakeLists.txt b/bolt/CMakeLists.txt
index 52c796518ac0..5c7d51e1e398 100644
--- a/bolt/CMakeLists.txt
+++ b/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})
diff --git a/clang/CMakeLists.txt b/clang/CMakeLists.txt
index f12712f55fb9..ab2ac9bc6b9a 100644
--- a/clang/CMakeLists.txt
+++ b/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 ${LLVM_DEFINITIONS_LIST})
+
   include(AddLLVM)
   include(TableGen)
   include(HandleLLVMOptions)
diff --git a/flang/CMakeLists.txt b/flang/CMakeLists.txt
index f358a93fdd79..56a96f590f0a 100644
--- a/flang/CMakeLists.txt
+++ b/flang/CMakeLists.txt
@@ -140,6 +140,11 @@ if (FLANG_STANDALONE_BUILD)
   if (NOT DEFINED LLVM_MAIN_SRC_DIR)
     set(LLVM_MAIN_SRC_DIR "${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)
diff --git a/lld/CMakeLists.txt b/lld/CMakeLists.txt
index 9b202cc5d489..80e25204a65e 100644
--- a/lld/CMakeLists.txt
+++ b/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 ${LLVM_DEFINITIONS_LIST})
+
   include(AddLLVM)
   include(TableGen)
   include(HandleLLVMOptions)
diff --git a/lldb/cmake/modules/LLDBStandalone.cmake b/lldb/cmake/modules/LLDBStandalone.cmake
index c9367214848f..1a4cdbfbb1cc 100644
--- a/lldb/cmake/modules/LLDBStandalone.cmake
+++ b/lldb/cmake/modules/LLDBStandalone.cmake
@@ -85,6 +85,10 @@ endif()
 # CMake modules to be in that directory as well.
 list(APPEND CMAKE_MODULE_PATH "${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)
diff --git a/mlir/CMakeLists.txt b/mlir/CMakeLists.txt
index 9e786154a2b4..daedc2be2258 100644
--- a/mlir/CMakeLists.txt
+++ b/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)
diff --git a/polly/CMakeLists.txt b/polly/CMakeLists.txt
index c3232752d307..52d1be6fe295 100644
--- a/polly/CMakeLists.txt
+++ b/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)