[Runtimes][Overlay] lay down nested swift modules ahead of CMake 4.1

This is needed in order to build target variants properly with a
SwiftDriver that has swiftlang/swift-driver#1856

Addresses rdar://154410676

Author: edymtt

Runtimes/Overlay/cmake/modules/EmitSwiftInterface.cmake

@@ -1,33 +1,54 @@
-# Generate and install swift interface files
+i# Generate and install swift interface files
 
 # TODO: CMake should learn how to model library evolution and generate this
 #       stuff automatically.
-
+if(POLICY CMP0195)
+  message(AUTHOR_WARNING [=[
+    This version of CMake supports the Swift module directory structure
+    Please consider checking the implementation of `emit_swift_interface``
+    to ensure it behaves as expected
+    ]=])
+endif()
 
 # Generate a swift interface file for the target if library evolution is enabled
 function(emit_swift_interface target)
   # Generate the target-variant binary swift module when performing zippered
   # build
-  if(SwiftOverlay_VARIANT_MODULE_TRIPLE)
-    set(variant_module_tmp_dir "${CMAKE_CURRENT_BINARY_DIR}/${target}-${SwiftOverlay_VARIANT_MODULE_TRIPLE}")
-    file(MAKE_DIRECTORY "${variant_module_tmp_dir}")
+  # Clean this up once CMake has nested swiftmodules in the build directory:
+  # https://gitlab.kitware.com/cmake/cmake/-/merge_requests/10664
+  # https://cmake.org/cmake/help/git-stage/policy/CMP0195.html
+
+  # We can't expand the Swift_MODULE_NAME target property in a generator
+  # expression or it will fail saying that the target doesn't exist.
+  get_target_property(module_name ${target} Swift_MODULE_NAME)
+  if(NOT module_name)
+    set(module_name ${target})
+  endif()
+  file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/${module_name}.swiftmodule")
+  target_compile_options(${target} PRIVATE
+    "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-emit-module-path ${CMAKE_CURRENT_BINARY_DIR}/${module_name}.swiftmodule/${SwiftCore_MODULE_TRIPLE}.swiftmodule>")
+  if(SwiftCore_VARIANT_MODULE_TRIPLE)
     target_compile_options(${target} PRIVATE
-      "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-emit-variant-module-path ${variant_module_tmp_dir}/${target}.swiftmodule>")
+      "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-emit-variant-module-path ${CMAKE_CURRENT_BINARY_DIR}/${module_name}.swiftmodule/${SwiftCore_VARIANT_MODULE_TRIPLE}.swiftmodule>")
   endif()
+  add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/${module_name}.swiftmodule/${SwiftCore_MODULE_TRIPLE}.swiftmodule"
+    DEPENDS ${target})
+  target_sources(${target}
+    INTERFACE
+      $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/${module_name}.swiftmodule/${SwiftCore_MODULE_TRIPLE}.swiftmodule>)
 
   # Generate textual swift interfaces is library-evolution is enabled
-  if(SwiftOverlay_ENABLE_LIBRARY_EVOLUTION)
+  if(SwiftCore_ENABLE_LIBRARY_EVOLUTION)
+    target_compile_options(${target} PRIVATE
+      $<$<COMPILE_LANGUAGE:Swift>:-emit-module-interface-path$<SEMICOLON>${CMAKE_CURRENT_BINARY_DIR}/${module_name}.swiftmodule/${SwiftCore_MODULE_TRIPLE}.swiftinterface>
+      $<$<COMPILE_LANGUAGE:Swift>:-emit-private-module-interface-path$<SEMICOLON>${CMAKE_CURRENT_BINARY_DIR}/${module_name}.swiftmodule/${SwiftCore_MODULE_TRIPLE}.private.swiftinterface>)
+    if(SwiftCore_VARIANT_MODULE_TRIPLE)
+      target_compile_options(${target} PRIVATE
+        "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-emit-variant-module-interface-path ${CMAKE_CURRENT_BINARY_DIR}/${module_name}.swiftmodule/${SwiftCore_VARIANT_MODULE_TRIPLE}.swiftinterface>"
+        "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-emit-variant-private-module-interface-path ${CMAKE_CURRENT_BINARY_DIR}/${module_name}.swiftmodule/${SwiftCore_VARIANT_MODULE_TRIPLE}.private.swiftinterface>")
+    endif()
     target_compile_options(${target} PRIVATE
-      $<$<COMPILE_LANGUAGE:Swift>:-emit-module-interface-path$<SEMICOLON>${CMAKE_CURRENT_BINARY_DIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftinterface>
-      $<$<COMPILE_LANGUAGE:Swift>:-emit-private-module-interface-path$<SEMICOLON>${CMAKE_CURRENT_BINARY_DIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.private.swiftinterface>
       $<$<COMPILE_LANGUAGE:Swift>:-library-level$<SEMICOLON>api>
       $<$<COMPILE_LANGUAGE:Swift>:-Xfrontend$<SEMICOLON>-require-explicit-availability=ignore>)
-
-      # Emit catalyst swiftmodules and interfaces
-      if(SwiftOverlay_VARIANT_MODULE_TRIPLE)
-        target_compile_options(${target} PRIVATE
-          "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-emit-variant-module-interface-path ${variant_module_tmp_dir}/${target}.swiftinterface>"
-          "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-emit-variant-private-module-interface-path ${variant_module_tmp_dir}/${target}.private.swiftinterface>")
-      endif()
   endif()
 endfunction()

Runtimes/Overlay/cmake/modules/InstallSwiftInterface.cmake

@@ -1,46 +1,13 @@
 
 # Install the generated swift interface files for the target.
 function(install_swift_interface target)
-  # Install binary swift modules
-  install(FILES "${CMAKE_CURRENT_BINARY_DIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftmodule"
-    RENAME "${SwiftOverlay_MODULE_TRIPLE}.swiftmodule"
-    DESTINATION "${SwiftOverlay_INSTALL_SWIFTMODULEDIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftmodule")
-  if(SwiftOverlay_VARIANT_MODULE_TRIPLE)
-    install(FILES "${CMAKE_CURRENT_BINARY_DIR}/${target}-${SwiftOverlay_VARIANT_MODULE_TRIPLE}/${target}.swiftmodule"
-      RENAME "${SwiftOverlay_VARIANT_MODULE_TRIPLE}.swiftmodule"
-      DESTINATION "${SwiftOverlay_INSTALL_SWIFTMODULEDIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftmodule")
+  # Swiftmodules are already in the directory structure
+  get_target_property(module_name ${target} Swift_MODULE_NAME)
+  if(NOT module_name)
+    set(module_name ${target})
   endif()
 
-  # Install Swift interfaces if library-evolution is enabled
-  if(SwiftOverlay_ENABLE_LIBRARY_EVOLUTION)
-    install(FILES "${CMAKE_CURRENT_BINARY_DIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftinterface"
-      RENAME "${SwiftOverlay_MODULE_TRIPLE}.swiftinterface"
-      DESTINATION "${SwiftOverlay_INSTALL_SWIFTMODULEDIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftmodule")
-
-    install(FILES "${CMAKE_CURRENT_BINARY_DIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.private.swiftinterface"
-      RENAME "${SwiftOverlay_MODULE_TRIPLE}.private.swiftinterface"
-      DESTINATION "${SwiftOverlay_INSTALL_SWIFTMODULEDIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftmodule")
-
-    # Install catalyst interface files
-    if(SwiftOverlay_VARIANT_MODULE_TRIPLE)
-      install(FILES "${CMAKE_CURRENT_BINARY_DIR}/${target}-${SwiftOverlay_VARIANT_MODULE_TRIPLE}/${target}.swiftinterface"
-        RENAME "${SwiftOverlay_VARIANT_MODULE_TRIPLE}.swiftinterface"
-        DESTINATION "${SwiftOverlay_INSTALL_SWIFTMODULEDIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftmodule")
-      install(FILES "${CMAKE_CURRENT_BINARY_DIR}/${target}-${SwiftOverlay_VARIANT_MODULE_TRIPLE}/${target}.private.swiftinterface"
-        RENAME "${SwiftOverlay_VARIANT_MODULE_TRIPLE}.private.swiftinterface"
-        DESTINATION "${SwiftOverlay_INSTALL_SWIFTMODULEDIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftmodule")
-    endif()
-  endif()
-
-  # Install Swift documentation interface files.
-  install(FILES "${CMAKE_CURRENT_BINARY_DIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftdoc"
-    RENAME "${SwiftOverlay_MODULE_TRIPLE}.swiftdoc"
-    DESTINATION "${SwiftOverlay_INSTALL_SWIFTMODULEDIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftmodule"
+  install(DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/${module_name}.swif\tmodule"
+    DESTINATION "${SwiftOverlay_INSTALL_SWIFTMODULEDIR}"
     COMPONENT SwiftOverlay_development)
-  if(SwiftOverlay_VARIANT_MODULE_TRIPLE)
-    install(FILES "${CMAKE_CURRENT_BINARY_DIR}/${target}-${SwiftOverlay_VARIANT_MODULE_TRIPLE}/${target}.swiftdoc"
-      RENAME "${SwiftOverlay_VARIANT_MODULE_TRIPLE}.swiftdoc"
-      DESTINATION "${SwiftOverlay_INSTALL_SWIFTMODULEDIR}/$<TARGET_PROPERTY:${target},Swift_MODULE_NAME>.swiftmodule"
-      COMPONENT SwiftOverlay_development)
-  endif()
-endfunction()
+endfunction()