[CMake] Add support for Swift buildtrees including CMake packages

This patch generates SwiftExports.cmake and SwiftConfig.cmake in the build tree to be compatible with CMake's `find_package` function for importing targets between CMake build trees. This will allow LLDB to consume Swift's targets and infer their transitive dependencies.

Author: Chris Bieneman

CMakeLists.txt

@@ -459,6 +459,9 @@ endif()
 
 set(SWIFT_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
 set(SWIFT_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}")
+set(SWIFT_CMAKE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules")
+set(SWIFT_MAIN_INCLUDE_DIR "${SWIFT_SOURCE_DIR}/include")
+set(SWIFT_INCLUDE_DIR "${CMAKE_CURRENT_BINARY_DIR}/include")
 
 set(SWIFT_RUNTIME_OUTPUT_INTDIR "${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin")
 set(SWIFT_LIBRARY_OUTPUT_INTDIR "${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib")
@@ -479,8 +482,8 @@ set(CMAKE_INCLUDE_CURRENT_DIR ON)
 
 # We'll need this once we have generated headers
 include_directories(BEFORE
-  ${CMAKE_CURRENT_BINARY_DIR}/include
-  ${CMAKE_CURRENT_SOURCE_DIR}/include
+  ${SWIFT_MAIN_INCLUDE_DIR}
+  ${SWIFT_INCLUDE_DIR}
   )
 
 # A convenience pattern to match Darwin platforms. Example:
@@ -954,6 +957,8 @@ if(SWIFT_INCLUDE_DOCS)
   add_subdirectory(docs)
 endif()
 
+add_subdirectory(cmake/modules)
+
 swift_install_in_component(license
   FILES "LICENSE.txt"
   DESTINATION "share/swift")

cmake/modules/AddSwift.cmake

@@ -1228,6 +1228,13 @@ function(add_swift_library name)
       ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
       LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
       RUNTIME DESTINATION bin)
+  swift_is_installing_component(dev is_installing)
+  
+  if(NOT is_installing)
+    set_property(GLOBAL APPEND PROPERTY SWIFT_BUILDTREE_EXPORTS ${name})
+  else()
+    set_property(GLOBAL APPEND PROPERTY SWIFT_EXPORTS ${name})
+  endif()
 endfunction()
 
 # Add a new Swift library.
@@ -2079,5 +2086,14 @@ function(add_swift_host_tool executable)
     swift_install_in_component(${ADDSWIFTHOSTTOOL_SWIFT_COMPONENT}
       TARGETS ${executable}
       RUNTIME DESTINATION bin)
+
+    swift_is_installing_component(${ADDSWIFTHOSTTOOL_SWIFT_COMPONENT}
+      is_installing)
+  
+    if(NOT is_installing)
+      set_property(GLOBAL APPEND PROPERTY SWIFT_BUILDTREE_EXPORTS ${executable})
+    else()
+      set_property(GLOBAL APPEND PROPERTY SWIFT_EXPORTS ${executable})
+    endif()
   endif()
 endfunction()

cmake/modules/CMakeLists.txt

@@ -0,0 +1,19 @@
+set(SWIFT_INSTALL_PACKAGE_DIR lib${LLVM_LIBDIR_SUFFIX}/cmake/swift)
+set(swift_cmake_builddir "${SWIFT_BINARY_DIR}/${SWIFT_INSTALL_PACKAGE_DIR}")
+
+# Generate build-tree exports list only
+set(SWIFT_EXPORTS_FILE ${swift_cmake_builddir}/SwiftExports.cmake)
+get_property(SWIFT_EXPORTS GLOBAL PROPERTY SWIFT_EXPORTS)
+get_property(SWIFT_BUILDTREE_EXPORTS GLOBAL PROPERTY SWIFT_BUILDTREE_EXPORTS)
+
+set(SWIFT_CONFIG_EXPORTS ${SWIFT_EXPORTS} ${SWIFT_BUILDTREE_EXPORTS})
+export(TARGETS ${SWIFT_CONFIG_EXPORTS} FILE ${SWIFT_EXPORTS_FILE})
+
+
+set(SWIFT_INCLUDE_DIRS ${SWIFT_INCLUDE_DIR} ${SWIFT_MAIN_INCLUDE_DIR})
+set(SWIFT_LIBRARY_DIRS ${SWIFT_LIBRARY_DIR})
+
+configure_file(
+  SwiftConfig.cmake.in
+  ${swift_cmake_builddir}/SwiftConfig.cmake
+  @ONLY)

cmake/modules/SwiftConfig.cmake.in

@@ -0,0 +1,23 @@
+# This file provides information and services to the final user.
+
+@SWIFT_CONFIG_CODE@
+
+set(SWIFT_VERSION @SWIFT_VERSION@)
+set(SWIFT_MAIN_SRC_DIR @SWIFT_MAIN_SRC_DIR@)
+
+set(SWIFT_INCLUDE_DIRS "@SWIFT_INCLUDE_DIR@")
+set(SWIFT_LIBRARY_DIRS "@SWIFT_CONFIG_LIBRARY_DIRS@")
+
+# These variables are duplicated, but they must match the LLVM variables of the
+# same name. The variables ending in "S" could some day become lists, and are
+# preserved for convention and compatibility.
+set(SWIFT_INCLUDE_DIR "@SWIFT_INCLUDE_DIR@")
+set(SWIFT_LIBRARY_DIR "@SWIFT_CONFIG_LIBRARY_DIRS@")
+
+set(SWIFT_CMAKE_DIR "@SWIFT_CMAKE_DIR@")
+set(SWIFT_BINARY_DIR "@SWIFT_BINARY_DIR@")
+
+if(NOT TARGET swift)
+  set(SWIFT_EXPORTED_TARGETS "@SWIFT_CONFIG_EXPORTS@")
+  include("@SWIFT_EXPORTS_FILE@")
+endif()