[clang] dfd9879 - [Clang] Make Clang copy its CMake modules into the build dir

[Andrzej Warzynski via cfe-commits]

Author: Andrzej Warzynski
Date: 2022-01-12T09:51:14Z
New Revision: dfd9879d6f43949443ba3c58cf3969ed582d7466

URL: https://github.com/llvm/llvm-project/commit/dfd9879d6f43949443ba3c58cf3969ed582d7466
DIFF: https://github.com/llvm/llvm-project/commit/dfd9879d6f43949443ba3c58cf3969ed582d7466.diff

LOG: [Clang] Make Clang copy its CMake modules into the build dir

LLVM has a documented mechanism for passing configuration information to
an out of tree project using CMake. See
https://llvm.org/docs/CMake.html#embedding-llvm-in-your-project.
Similar logic applies to "standalone" builds of other sub-projects
within LLVM that depend on each other. For example, a standalone build
of Flang will use this mechanism to acquire Clang's configuration.

Currently, the relevant CMake modules for Clang will only be copied into
the installation directory. This means that in order to configure a
standalone build of Flang, one has to first build and then install
Clang. This is not required for LLVM nor for MLIR - other sub-projects
that Flang depends on (i.e. the CMake modules for LLVM and MLIR are
available in the build dir, so installation is not needed).

This change removes the need for installing Clang in order to access its
configuration. It makes sure that the required CMake modules are copied
into the build directory. This will make Clang behave consistently with
LLVM and MLIR in this respect. It will also simplify building Flang as
standalone sub-project.

Differential Revision: https://reviews.llvm.org/D116731

Added: 
    

Modified: 
    clang/cmake/modules/CMakeLists.txt

Removed: 
    


################################################################################
diff  --git a/clang/cmake/modules/CMakeLists.txt b/clang/cmake/modules/CMakeLists.txt
index 3890ea14d06c6..e9cc1240dafb7 100644
--- a/clang/cmake/modules/CMakeLists.txt
+++ b/clang/cmake/modules/CMakeLists.txt
@@ -29,6 +29,14 @@ configure_file(
 set(CLANG_CONFIG_CMAKE_DIR)
 set(CLANG_CONFIG_LLVM_CMAKE_DIR)
 
+# For compatibility with projects that include(ClangConfig)
+# via CMAKE_MODULE_PATH, place API modules next to it.
+file(COPY .
+  DESTINATION ${clang_cmake_builddir}
+  FILES_MATCHING PATTERN *.cmake
+  PATTERN CMakeFiles EXCLUDE
+  )
+
 # Generate ClangConfig.cmake for the install tree.
 find_prefix_from_config(CLANG_CONFIG_CODE CLANG_INSTALL_PREFIX "${CLANG_INSTALL_PACKAGE_DIR}")
 set(CLANG_CONFIG_CMAKE_DIR "\${CLANG_INSTALL_PREFIX}/${CLANG_INSTALL_PACKAGE_DIR}")