[cmake] Prepare for stage2 bootstrap swift build

CMakeLists.txt

@@ -507,6 +507,11 @@ execute_process(COMMAND ${CMAKE_MAKE_PROGRAM} --version
 message(STATUS "CMake Make Program (${CMAKE_MAKE_PROGRAM}) Version: ${_CMAKE_MAKE_PROGRAM_VERSION}")
 message(STATUS "C Compiler (${CMAKE_C_COMPILER}) Version: ${CMAKE_C_COMPILER_VERSION}")
 message(STATUS "C++ Compiler (${CMAKE_CXX_COMPILER}) Version: ${CMAKE_CXX_COMPILER_VERSION}")
+if (CMAKE_Swift_COMPILER)
+  message(STATUS "Swift Compiler (${CMAKE_Swift_COMPILER}) Version: ${CMAKE_Swift_COMPILER_VERSION}")
+else()
+  message(STATUS "Swift Compiler (None).")
+endif()
 if(SWIFT_PATH_TO_CMARK_BUILD)
   execute_process(COMMAND ${SWIFT_PATH_TO_CMARK_BUILD}/src/cmark --version
     OUTPUT_VARIABLE _CMARK_VERSION
@@ -523,6 +528,13 @@ else()
   set(SWIFT_PREBUILT_CLANG TRUE)
 endif()
 
+# Also mark if we have a prebuilt swift before we do anything.
+if("${SWIFT_NATIVE_SWIFT_TOOLS_PATH}" STREQUAL "")
+  set(SWIFT_PREBUILT_SWIFT FALSE)
+else()
+  set(SWIFT_PREBUILT_SWIFT TRUE)
+endif()
+
 include(SwiftSharedCMakeConfig)
 
 # NOTE: We include this before SwiftComponents as it relies on some LLVM CMake

cmake/modules/AddSwift.cmake

@@ -600,13 +600,22 @@ function(add_swift_host_library name)
     # find all of the necessary swift libraries on Darwin.
     if (NOT ASHL_PURE_SWIFT)
       if (CMAKE_Swift_COMPILER)
-        # Add in the SDK directory for the host platform and add an rpath.
-        target_link_directories(${name} PRIVATE
-          ${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_ARCH_${SWIFT_HOST_VARIANT_ARCH}_PATH}/usr/lib/swift)
         # Add in the toolchain directory so we can grab compatibility libraries
         get_filename_component(TOOLCHAIN_BIN_DIR ${CMAKE_Swift_COMPILER} DIRECTORY)
         get_filename_component(TOOLCHAIN_LIB_DIR "${TOOLCHAIN_BIN_DIR}/../lib/swift/macosx" ABSOLUTE)
         target_link_directories(${name} PUBLIC ${TOOLCHAIN_LIB_DIR})
+
+        # Add in the SDK directory for the host platform.
+        #
+        # NOTE: We do this /after/ target_link_directorying TOOLCHAIN_LIB_DIR to
+        # ensure that we first find libraries from the toolchain, rather than
+        # from the SDK. The reason why this is important is that when we perform
+        # a stage2 build, this path is into the stage1 build. This is not a pure
+        # SDK and also contains compatibility libraries. We need to make sure
+        # that the compiler sees the actual toolchain's compatibility libraries
+        # first before the just built compability libraries or build errors occur.
+        target_link_directories(${name} PRIVATE
+          ${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_ARCH_${SWIFT_HOST_VARIANT_ARCH}_PATH}/usr/lib/swift)
       endif()
     endif()
 
@@ -808,14 +817,23 @@ function(add_swift_host_tool executable)
     # host side tools but link with clang, add the appropriate -L paths so we
     # find all of the necessary swift libraries on Darwin.
     if (CMAKE_Swift_COMPILER)
-      # Add in the SDK directory for the host platform and add an rpath.
-      target_link_directories(${executable} PRIVATE
-        ${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_ARCH_${SWIFT_HOST_VARIANT_ARCH}_PATH}/usr/lib/swift)
       # Add in the toolchain directory so we can grab compatibility libraries
       get_filename_component(TOOLCHAIN_BIN_DIR ${CMAKE_Swift_COMPILER} DIRECTORY)
       get_filename_component(TOOLCHAIN_LIB_DIR "${TOOLCHAIN_BIN_DIR}/../lib/swift/macosx" ABSOLUTE)
       target_link_directories(${executable} PUBLIC ${TOOLCHAIN_LIB_DIR})
 
+      # Add in the SDK directory for the host platform and add an rpath.
+      #
+      # NOTE: We do this /after/ target_link_directorying TOOLCHAIN_LIB_DIR to
+      # ensure that we first find libraries from the toolchain, rather than from
+      # the SDK. The reason why this is important is that when we perform a
+      # stage2 build, this path is into the stage1 build. This is not a pure SDK
+      # and also contains compatibility libraries. We need to make sure that the
+      # compiler sees the actual toolchain's compatibility libraries first
+      # before the just built compability libraries or build errors occur.
+      target_link_directories(${executable} PRIVATE
+        ${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_ARCH_${SWIFT_HOST_VARIANT_ARCH}_PATH}/usr/lib/swift)
+
       if (ASHT_HAS_LIBSWIFT AND SWIFT_TOOLS_ENABLE_LIBSWIFT)
         # Workaround to make lldb happy: we have to explicitly add all libswift modules
         # to the linker command line.

stdlib/cmake/modules/SwiftSource.cmake

@@ -630,7 +630,17 @@ function(_compile_swift_files
   if(CMAKE_HOST_SYSTEM_NAME STREQUAL Windows)
     set(HOST_EXECUTABLE_SUFFIX .exe)
   endif()
-  set(swift_compiler_tool "${SWIFT_NATIVE_SWIFT_TOOLS_PATH}/swiftc${HOST_EXECUTABLE_SUFFIX}")
+  if(SWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER)
+    if(SWIFT_PREBUILT_SWIFT)
+      set(swift_compiler_tool "${SWIFT_NATIVE_SWIFT_TOOLS_PATH}/swiftc${HOST_EXECUTABLE_SUFFIX}")
+    elseif(CMAKE_Swift_COMPILER)
+      set(swift_compiler_tool "${CMAKE_Swift_COMPILER}")
+    else()
+      message(ERROR "Must pass in prebuilt tools using SWIFT_NATIVE_SWIFT_TOOLS_PATH or set CMAKE_Swift_COMPILER")
+    endif()
+  else()
+    set(swift_compiler_tool "${SWIFT_NATIVE_SWIFT_TOOLS_PATH}/swiftc${HOST_EXECUTABLE_SUFFIX}")
+  endif()
 
   set(swift_compiler_tool_dep)
   if(SWIFT_INCLUDE_TOOLS)