Tests: add a check for the Swift compiler

This ensures that the tests only run when the Swift compiler is present.

1 files changed, 61 insertions, 0 deletions

diff --git a/Tests/CheckSwift.cmake b/Tests/CheckSwift.cmake
new file mode 100644
index 0000000..fcbae7e
--- /dev/null
+++ b/Tests/CheckSwift.cmake
@@ -0,0 +1,61 @@
+if(NOT CMAKE_GENERATOR MATCHES "Xcode|Ninja")
+  set(CMAKE_Swift_COMPILER "")
+  return()
+endif()
+
+if(NOT DEFINED CMAKE_Swift_COMPILER)
+  set(_desc "Looking for a Swift compiler")
+  message(STATUS ${_desc})
+
+  file(REMOVE_RECURSE ${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/CheckSwift)
+
+  file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/CheckSwift/CMakeLists.txt"
+  "cmake_minimum_required(VERSION 3.14)
+project(CheckSwift Swift)
+file(WRITE \"\${CMAKE_CURRENT_BINARY_DIR}/result.cmake\"
+  \"set(CMAKE_Swift_COMPILER \\\"\${CMAKE_Swift_COMPILER}\\\")\\n\"
+  \"set(CMAKE_Swift_FLAGS \\\"\${CMAKE_Swift_FLAGS}\\\")\\n\")
+")
+
+  if(CMAKE_GENERATOR_INSTANCE)
+    set(_D_CMAKE_GENERATOR_INSTANCE "-DCMAKE_GENERATOR_INSTANCE:INTERNAL=${CMAKE_GENERATOR_INSTANCE}")
+  else()
+    set(_D_CMAKE_GENERATOR_INSTANCE "")
+  endif()
+
+  execute_process(WORKING_DIRECTORY
+                    ${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/CheckSwift
+                  COMMAND
+                    ${CMAKE_COMMAND} . -G ${CMAKE_GENERATOR}
+                                       -A "${CMAKE_GENERATOR_PLATFORM}"
+                                       -T "${CMAKE_GENERATOR_TOOLSET}"
+                                       ${_D_CMAKE_GENERATOR_INSTANCE}
+                  TIMEOUT
+                    60
+                  OUTPUT_VARIABLE
+                    output
+                  ERROR_VARIABLE
+                    output
+                  RESULT_VARIABLE
+                    result)
+
+  include(${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/CheckSwift/result.cmake
+    OPTIONAL)
+  if(CMAKE_Swift_COMPILER AND "${result}" STREQUAL "0")
+    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
+      "${_desc} passed with the following output:\n"
+      "${output}\n")
+  else()
+    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
+      "${_desc} failed with the following output:\n"
+      "${output}\n")
+  endif()
+
+  message(STATUS "${_desc} - ${CMAKE_Swift_COMPILER}")
+
+  set(CMAKE_Swift_COMPILER "${CMAKE_Swift_COMPILER}" CACHE FILEPATH "Swift compiler")
+  set(CMAKE_Swift_FLAGS "${CMAKE_Swift_FLAGS}" CACHE STRING "Swift flags")
+
+  mark_as_advanced(CMAKE_Swift_COMPILER)
+  mark_as_advanced(CMAKE_Swift_FLAGS)
+endif()