Separate dependency fetching

CMakeLists.txt

@@ -1,5 +1,8 @@
 cmake_minimum_required(VERSION 3.26)
 
+#
+# Standard project boilerplate
+#
 project(SwiftCMakeXCTesting
   VERSION 0.1.0
   DESCRIPTION "Cross-platform support for using XCTest in Swift projects"
@@ -8,49 +11,13 @@ project(SwiftCMakeXCTesting
 )
 enable_testing()
 
+list(PREPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake/modules)
+
 if (PROJECT_IS_TOP_LEVEL)
   include(${PROJECT_SOURCE_DIR}/cmake/TopLevelDefaults.cmake)
 endif()
 
-#
-# Dependencies
-#
-
-include(FetchContent)
-
-set(_XCTESTDISCOVERY_SAVED_BUILD_TESTING ${BUILD_TESTING})
-set(_XCTESTDISCOVERY_SAVED_BUILD_EXAMPLES ${BUILD_EXAMPLES})
-set(_XCTESTDISCOVERY_VENDOR_DEPENDENCIES)
-
-set(BUILD_EXAMPLES NO)
-set(BUILD_TESTING NO)
-
-if("${SWIFT_HOST_MODULE_TRIPLE}" STREQUAL "")
-  execute_process(COMMAND ${CMAKE_Swift_COMPILER} -print-target-info OUTPUT_VARIABLE target-info)
-  string(JSON SWIFT_HOST_MODULE_TRIPLE GET ${target-info} target moduleTriple)
-endif()
-
-FetchContent_Declare(SwiftSyntax
-  GIT_REPOSITORY https://github.com/apple/swift-syntax.git
-  GIT_TAG        main
-  FIND_PACKAGE_ARGS CONFIG
-)
-
-FetchContent_Declare(ArgumentParser
-  GIT_REPOSITORY https://github.com/apple/swift-argument-parser.git
-  GIT_TAG        1.3.0
-  FIND_PACKAGE_ARGS CONFIG
-)
-
-FetchContent_MakeAvailable(ArgumentParser SwiftSyntax)
-target_compile_options(SwiftCompilerPluginMessageHandling PRIVATE -suppress-warnings)
-target_compile_options(SwiftParser PRIVATE -suppress-warnings)
-target_compile_options(SwiftParserDiagnostics PRIVATE -suppress-warnings)
-target_compile_options(SwiftSyntaxMacroExpansion PRIVATE -suppress-warnings)
-target_compile_options(SwiftOperators PRIVATE -suppress-warnings)
 
-set(BUILD_TESTING ${_XCTESTDISCOVERY_SAVED_BUILD_TESTING})
-set(BUILD_EXAMPLES ${_XCTESTDISCOVERY_SAVED_BUILD_EXAMPLES})
 
 #
 # Local targets

cmake/TopLevelDefaults.cmake

@@ -1,2 +1,4 @@
 # commands used to create an easy development environment when
 # building this project directly (not as a dependency).
+
+include(SwiftCMakeXCTesting_FetchDependencies)

cmake/modules/SwiftCMakeXCTesting_FetchDependencies.cmake

@@ -0,0 +1,40 @@
+# Fetches dependencies for SwiftCMakeXCTesting.
+include(FetchContent)
+
+# See https://github.com/apple/swift-syntax/pull/2454, which will hopefully make this clause
+# unnecessary.  Without it CMake will fatal error when loading SwiftSyntax on some platforms.
+if("${SWIFT_HOST_MODULE_TRIPLE}" STREQUAL "")
+  execute_process(COMMAND ${CMAKE_Swift_COMPILER}
+    -print-target-info OUTPUT_VARIABLE target-info)
+  string(JSON SWIFT_HOST_MODULE_TRIPLE GET ${target-info} target moduleTriple)
+endif()
+
+FetchContent_Declare(SwiftSyntax
+  GIT_REPOSITORY https://github.com/apple/swift-syntax.git
+  GIT_TAG        main
+  FIND_PACKAGE_ARGS CONFIG
+)
+
+FetchContent_Declare(ArgumentParser
+  GIT_REPOSITORY https://github.com/apple/swift-argument-parser.git
+  GIT_TAG        1.3.0
+  FIND_PACKAGE_ARGS CONFIG
+)
+
+set(_XCTESTDISCOVERY_SAVED_BUILD_TESTING ${BUILD_TESTING})
+set(_XCTESTDISCOVERY_SAVED_BUILD_EXAMPLES ${BUILD_EXAMPLES})
+
+set(BUILD_EXAMPLES NO)
+set(BUILD_TESTING NO)
+
+FetchContent_MakeAvailable(ArgumentParser SwiftSyntax)
+
+target_compile_options(SwiftCompilerPluginMessageHandling PRIVATE -suppress-warnings)
+target_compile_options(SwiftParser PRIVATE -suppress-warnings)
+target_compile_options(SwiftParserDiagnostics PRIVATE -suppress-warnings)
+target_compile_options(SwiftSyntaxMacroExpansion PRIVATE -suppress-warnings)
+target_compile_options(SwiftOperators PRIVATE -suppress-warnings)
+
+
+set(BUILD_TESTING ${_XCTESTDISCOVERY_SAVED_BUILD_TESTING})
+set(BUILD_EXAMPLES ${_XCTESTDISCOVERY_SAVED_BUILD_EXAMPLES})