From 451af84221182ab1cba74cf02705e6aff5f5cad2 Mon Sep 17 00:00:00 2001
From: Petr Hosek <phosek@google.com>
Date: Thu, 5 Sep 2024 18:58:29 +0000
Subject: [PATCH] [CMake] Passthrough variables for packages to subbuilds

These packaged are imported by LLVMConfig.cmake and so we should be
passing through the necessary variables from the parent build into
the subbuilds.

We use `CMAKE_CACHE_DEFAULT_ARGS` so subbuilds can override these
variables if needed.
---
 .../modules/LLVMExternalProjectUtils.cmake    | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/llvm/cmake/modules/LLVMExternalProjectUtils.cmake b/llvm/cmake/modules/LLVMExternalProjectUtils.cmake
index eef0c16f6847e..f7e1165bc4b94 100644
--- a/llvm/cmake/modules/LLVMExternalProjectUtils.cmake
+++ b/llvm/cmake/modules/LLVMExternalProjectUtils.cmake
@@ -156,6 +156,32 @@ function(llvm_ExternalProject_Add name source_dir)
     set_target_properties(${name}-clear PROPERTIES FOLDER "${ARG_FOLDER}")
   endif ()
 
+  set(DEFAULT_PASSTHROUGH_VARIABLES
+    LibEdit_INCLUDE_DIRS
+    LibEdit_LIBRARIES
+    ZLIB_INCLUDE_DIR
+    ZLIB_LIBRARY
+    zstd_INCLUDE_DIR
+    zstd_LIBRARY
+    LIBXML2_LIBRARY
+    LIBXML2_INCLUDE_DIR
+    CURL_INCLUDE_DIR
+    CURL_LIBRARY
+    HTTPLIB_INCLUDE_DIR
+    HTTPLIB_HEADER_PATH
+    Python3_EXECUTABLE
+    Python3_LIBRARIES
+    Python3_INCLUDE_DIRS
+    Python3_RPATH
+    )
+  foreach(variable ${DEFAULT_PASSTHROUGH_VARIABLES})
+    get_property(is_value_set CACHE ${variable} PROPERTY VALUE SET)
+    if(${is_value_set})
+      get_property(value CACHE ${variable} PROPERTY VALUE)
+      list(APPEND CMAKE_CACHE_DEFAULT_ARGS "-D${variable}:STRING=${value}")
+    endif()
+  endforeach()
+
   # Find all variables that start with a prefix and propagate them through
   get_cmake_property(variableNames VARIABLES)
 
@@ -363,6 +389,7 @@ function(llvm_ExternalProject_Add name source_dir)
                -DCMAKE_EXPORT_COMPILE_COMMANDS=1
                ${cmake_args}
                ${PASSTHROUGH_VARIABLES}
+    CMAKE_CACHE_DEFAULT_ARGS ${CMAKE_CACHE_DEFAULT_ARGS}
     INSTALL_COMMAND ""
     STEP_TARGETS configure build
     BUILD_ALWAYS 1