build: support building swift-driver outside of the toolchain

We can now vendor the dependencies allowing us to build a separate copy
of the dependencies when building the package if it is not provided for.
This enables building the package standalone for debugging in scenarios
where SPM is unable to build the package (e.g. due to incorrect
linking).

Author: compnerd

CMakeLists.txt

@@ -6,43 +6,90 @@
 # See http://swift.org/LICENSE.txt for license information
 # See http://swift.org/CONTRIBUTORS.txt for Swift project authors
 
+cmake_minimum_required(VERSION 3.19.6)
+
+if(POLICY CMP0077)
+  cmake_policy(SET CMP0077 NEW)
+endif()
+
 if(POLICY CMP0091)
   cmake_policy(SET CMP0091 NEW)
 endif()
 
-cmake_minimum_required(VERSION 3.19.6)
-
-list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules)
-
 project(SwiftDriver LANGUAGES C Swift)
 
-set(CMAKE_Swift_LANGUAGE_VERSION 5)
-set(CMAKE_Swift_MODULE_DIRECTORY ${CMAKE_BINARY_DIR}/swift)
-set(CMAKE_Swift_COMPILE_OPTIONS_MSVC_RUNTIME_LIBRARY MultiThreadedDLL)
-
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
 
 set(CMAKE_MACOSX_RPATH YES)
 set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreadedDLL)
+list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules)
+
+set(CMAKE_Swift_COMPILE_OPTIONS_MSVC_RUNTIME_LIBRARY MultiThreadedDLL)
+set(CMAKE_Swift_LANGUAGE_VERSION 5)
+set(CMAKE_Swift_MODULE_DIRECTORY ${CMAKE_BINARY_DIR}/swift)
 
 # ensure Swift compiler can find _CSwiftScan
 add_compile_options($<$<COMPILE_LANGUAGE:Swift>:-I$<SEMICOLON>${CMAKE_CURRENT_SOURCE_DIR}/Sources/CSwiftScan/include>)
 
 option(BUILD_SHARED_LIBS "Build shared libraries by default" YES)
 
-find_package(TSC CONFIG REQUIRED)
+# Toolchain Vended Dependencies
+find_package(dispatch QUIET)
+find_package(Foundation QUIET)
+
+include(FetchContent)
+
+set(_SD_SAVED_BUILD_TESTING ${BUILD_TESTING})
+set(_SD_SAVED_BUILD_EXAMPLES ${BUILD_EXAMPLES})
+
+set(BUILD_TESTING NO)
+set(BUILD_EXAMPLES NO)
+
+find_package(ArgumentParser CONFIG)
+if(NOT ArgumentParser_FOUND)
+  message("-- Vending swift-argument-parser")
+  FetchContent_Declare(ArgumentParser
+    GIT_REPOSITORY https://github.com/apple/swift-argument-parser
+    GIT_TAG 1.2.3)
+  FetchContent_MakeAvailable(ArgumentParser)
+endif()
 
 find_package(LLBuild CONFIG)
 if(NOT LLBuild_FOUND)
-  find_package(LLBuild REQUIRED)
+  if(APPLE)
+    find_package(LLBuild REQUIRED)
+  else()
+    message("-- Vending swift-llbuild")
+    set(LLBUILD_SUPPORT_BINDINGS Swift)
+    FetchContent_Declare(LLBuild
+      GIT_REPOSITORY https://github.com/apple/swift-llbuild
+      GIT_TAG main)
+    FetchContent_MakeAvailable(LLBuild)
+  endif()
 endif()
 
-find_package(dispatch QUIET)
-find_package(Foundation QUIET)
-find_package(Yams CONFIG REQUIRED)
-find_package(ArgumentParser CONFIG REQUIRED)
+find_package(TSC CONFIG)
+if(NOT TSC_FOUND)
+  message("-- Vending swift-tools-support-core")
+  FetchContent_Declare(ToolsSupportCore
+    GIT_REPOSITORY https://github.com/apple/swift-tools-support-core
+    GIT_TAG main)
+  FetchContent_MakeAvailable(ToolsSupportCore)
+endif()
+
+find_package(Yams CONFIG)
+if(NOT Yams_FOUND)
+  message("-- Vending yams")
+  FetchContent_Declare(Yams
+    GIT_REPOSITORY https://github.com/jpsim/yams
+    GIT_TAG 5.0.6)
+  FetchContent_MakeAvailable(Yams)
+endif()
+
+set(BUILD_TESTING ${_SD_SAVED_BUILD_TESTING})
+set(BUILD_EXAMPLES ${_SD_SAVED_BUILD_EXAMPLES})
 
 add_subdirectory(Sources)
 add_subdirectory(cmake/modules)