Merge pull request #5034 from llvm-beanz/fix-swiftshims-dependency

[CMake] Fix bad dependency in symlink_clang_headers

Author: Chris B

cmake/modules/SwiftComponents.cmake

@@ -122,3 +122,29 @@ function(swift_install_in_component component)
     install(${ARGN})
   endif()
 endfunction()
+
+function(swift_install_symlink_component component)
+  cmake_parse_arguments(
+      ARG # prefix
+      "" "LINK_NAME;TARGET;DESTINATION" "" ${ARGN})
+  precondition(ARG_LINK_NAME MESSAGE "LINK_NAME is required")
+  precondition(ARG_TARGET MESSAGE "TARGET is required")
+  precondition(ARG_DESTINATION MESSAGE "DESTINATION is required")
+
+  swift_is_installing_component("${component}" is_installing)
+  if (NOT is_installing)
+    return()
+  endif()
+
+  foreach(path ${CMAKE_MODULE_PATH})
+    if(EXISTS ${path}/LLVMInstallSymlink.cmake)
+      set(INSTALL_SYMLINK ${path}/LLVMInstallSymlink.cmake)
+      break()
+    endif()
+  endforeach()
+  precondition(INSTALL_SYMLINK
+    MESSAGE "LLVMInstallSymlink script must be available.")
+
+  install(SCRIPT ${INSTALL_SYMLINK}
+          CODE "install_symlink(${ARG_LINK_NAME} ${ARG_TARGET} ${ARG_DESTINATION})")
+endfunction()

stdlib/public/SwiftShims/CMakeLists.txt

@@ -80,22 +80,8 @@ add_custom_command_target(unused_var
       "${clang_headers_location}"
       "${SWIFTLIB_DIR}/clang"
 
-    # Create a broken symlink that points to '../clang/$VERSION'.  It is not
-    # used when running Swift tools from the build tree directly, but we will
-    # install it in such a way that it points to Clang installation.  If the 
-    # link can be resolved, CMake would try to follow it when installing the
-    # project under certain conditions.
-    COMMAND
-      "${CMAKE_COMMAND}" "-E" "make_directory" "${SWIFTLIB_DIR}/install-tmp/install-tmp"
-    COMMAND
-      "${CMAKE_COMMAND}" "-E" "remove"
-      "${SWIFTLIB_DIR}/install-tmp/install-tmp/clang"
-    COMMAND
-      "${CMAKE_COMMAND}" "-E" "create_symlink"
-      "../clang/${CLANG_VERSION}"
-      "${SWIFTLIB_DIR}/install-tmp/install-tmp/clang"
     CUSTOM_TARGET_NAME "symlink_clang_headers"
-    OUTPUT "${SWIFTLIB_DIR}/clang" "${SWIFTLIB_DIR}/install-tmp/install-tmp/clang"
+    OUTPUT "${SWIFTLIB_DIR}/clang"
     COMMENT "Symlinking Clang resource headers into ${SWIFTLIB_DIR}/clang")
 add_dependencies(copy_shim_headers symlink_clang_headers)
 
@@ -110,10 +96,10 @@ swift_install_in_component(clang-builtin-headers
     DESTINATION "lib/swift/clang"
     PATTERN "*.h")
 
-# Alternatively, install a symbolic link to the Clang resource directory.
-swift_install_in_component(clang-resource-dir-symlink
-    DIRECTORY "${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib/swift/install-tmp/install-tmp/clang"
-    DESTINATION "lib/swift")
+swift_install_symlink_component(clang-resource-dir-symlink
+  LINK_NAME clang
+  TARGET ../clang/${CLANG_VERSION}
+  DESTINATION "lib/swift")
 
 # Possibly install Clang headers under Clang's resource directory in case we
 # need to use a different version of the headers than the installed Clang. This