FindPython: Add capability to specify Python implementations

Through hint Python_FIND_IMPLEMENTATIONS it is possble to specify, as an
ordered list, which implementations must be searched for.
Currently possible values are:
* CPython
* IronPython

4 files changed, 80 insertions, 2 deletions

diff --git a/Tests/FindPython/CMakeLists.txt b/Tests/FindPython/CMakeLists.txt
index c72b5e28c8..072a993828 100644
--- a/Tests/FindPython/CMakeLists.txt
+++ b/Tests/FindPython/CMakeLists.txt
@@ -314,6 +314,29 @@ if(CMake_TEST_FindPython_Conda)
     )
 endif()
 
+if (CMake_TEST_FindPython AND CMake_TEST_FindPython_IronPython)
+  add_test(NAME FindPython.Implementation.CPython COMMAND
+    ${CMAKE_CTEST_COMMAND} -C $<CONFIGURATION>
+    --build-and-test
+    "${CMake_SOURCE_DIR}/Tests/FindPython/Implementation"
+    "${CMake_BINARY_DIR}/Tests/FindPython/Implementation.CPython"
+    ${build_generator_args}
+    --build-project TestImplementationCPython
+    --build-options ${build_options} -DPython_REQUESTED_VERSION=2 -DPython_REQUESTED_IMPLEMENTATIONS=CPython
+    --test-command ${CMAKE_CTEST_COMMAND} -V -C $<CONFIGURATION>
+    )
+  add_test(NAME FindPython.Implementation.IronPython COMMAND
+    ${CMAKE_CTEST_COMMAND} -C $<CONFIGURATION>
+    --build-and-test
+    "${CMake_SOURCE_DIR}/Tests/FindPython/Implementation"
+    "${CMake_BINARY_DIR}/Tests/FindPython/Implementation.IronPython"
+    ${build_generator_args}
+    --build-project TestImplementationIronPython
+    --build-options ${build_options} -DPython_REQUESTED_VERSION=2 -DPython_REQUESTED_IMPLEMENTATION=IronPython
+    --test-command ${CMAKE_CTEST_COMMAND} -V -C $<CONFIGURATION>
+    )
+endif()
+
 if(CMake_TEST_FindPython_IronPython)
   add_test(NAME FindPython.IronPython2.LOCATION COMMAND
     ${CMAKE_CTEST_COMMAND} -C $<CONFIGURATION>
diff --git a/Tests/FindPython/Implementation/CMakeLists.txt b/Tests/FindPython/Implementation/CMakeLists.txt
new file mode 100644
index 0000000000..d64fa1edd4
--- /dev/null
+++ b/Tests/FindPython/Implementation/CMakeLists.txt
@@ -0,0 +1,37 @@
+cmake_minimum_required(VERSION 3.1)
+
+project(TestImplementation${Python_REQUESTED_IMPLEMENTATION} C)
+
+
+set (Python${Python_REQUESTED_VERSION}_FIND_IMPLEMENTATIONS ${Python_REQUESTED_IMPLEMENTATION})
+
+find_package(Python${Python_REQUESTED_VERSION} COMPONENTS Interpreter)
+if (NOT Python${Python_REQUESTED_VERSION}_FOUND OR NOT Python${Python_REQUESTED_VERSION}_Interpreter_FOUND)
+  message (FATAL_ERROR "Fail to found Python${Python_REQUESTED_VERSION}")
+endif()
+
+if (Python_REQUESTED_IMPLEMENTATION STREQUAL "IronPython"
+    AND NOT Python${Python_REQUESTED_VERSION}_INTERPRETER_ID STREQUAL "IronPython")
+  message (FATAL_ERROR "Erroneous interpreter ID (${Python${Python_REQUESTED_VERSION}_INTERPRETER_ID})")
+endif()
+if (Python_REQUESTED_IMPLEMENTATION STREQUAL "CPython"
+    AND Python${Python_REQUESTED_VERSION}_INTERPRETER_ID STREQUAL "IronPython")
+  message (FATAL_ERROR "Erroneous interpreter ID (${Python${Python_REQUESTED_VERSION}_INTERPRETER_ID})")
+endif()
+
+
+set (Python_FIND_IMPLEMENTATIONS ${Python_REQUESTED_IMPLEMENTATION})
+
+find_package(Python ${Python_REQUESTED_VERSION} REQUIRED COMPONENTS Interpreter)
+if (NOT Python_FOUND OR NOT Python_Interpreter_FOUND)
+  message (FATAL_ERROR "Fail to found Python ${Python_REQUESTED_VERSION}")
+endif()
+
+if (Python_REQUESTED_IMPLEMENTATION STREQUAL "IronPython"
+    AND NOT Python_INTERPRETER_ID STREQUAL "IronPython")
+  message (FATAL_ERROR "Erroneous interpreter ID (${Python_INTERPRETER_ID})")
+endif()
+if (Python_REQUESTED_IMPLEMENTATION STREQUAL "CPython"
+    AND Python_INTERPRETER_ID STREQUAL "IronPython")
+  message (FATAL_ERROR "Erroneous interpreter ID (${Python_INTERPRETER_ID})")
+endif()
diff --git a/Tests/FindPython/IronPython/CMakeLists.txt b/Tests/FindPython/IronPython/CMakeLists.txt
index c96a3e031b..3493c29bbc 100644
--- a/Tests/FindPython/IronPython/CMakeLists.txt
+++ b/Tests/FindPython/IronPython/CMakeLists.txt
@@ -2,11 +2,20 @@ cmake_minimum_required(VERSION 3.1)
 
 project(TestIronPython C)
 
-find_package(Python ${Python_REQUESTED_VERSION} REQUIRED COMPONENTS Interpreter Compiler)
+set (Python_FIND_IMPLEMENTATIONS IronPython)
+
+find_package(Python ${Python_REQUESTED_VERSION} COMPONENTS Interpreter Compiler)
 if (NOT Python_FOUND)
   message (FATAL_ERROR "Fail to found Python ${Python_REQUESTED_VERSION}")
 endif()
 
+if (NOT Python_Interpreter_FOUND)
+  message (FATAL_ERROR "Fail to found Python Interpreter")
+endif()
+if (NOT Python_INTERPRETER_ID STREQUAL "IronPython")
+  message (FATAL_ERROR "Erroneous interpreter ID (${Python_INTERPRETER_ID})")
+endif()
+
 if (NOT Python_Compiler_FOUND)
   message (FATAL_ERROR "Fail to found Python Compiler")
 endif()
diff --git a/Tests/FindPython/IronPython2/CMakeLists.txt b/Tests/FindPython/IronPython2/CMakeLists.txt
index 43ec309f57..1db798cc22 100644
--- a/Tests/FindPython/IronPython2/CMakeLists.txt
+++ b/Tests/FindPython/IronPython2/CMakeLists.txt
@@ -2,11 +2,20 @@ cmake_minimum_required(VERSION 3.1)
 
 project(TestIronPython2 C)
 
-find_package(Python2 REQUIRED COMPONENTS Interpreter Compiler)
+set (Python2_FIND_IMPLEMENTATIONS "IronPython")
+
+find_package(Python2 COMPONENTS Interpreter Compiler)
 if (NOT Python2_FOUND)
   message (FATAL_ERROR "Fail to found Python 2")
 endif()
 
+if (NOT Python2_Interpreter_FOUND)
+  message (FATAL_ERROR "Fail to found Python 2 Interpreter")
+endif()
+if (NOT Python2_INTERPRETER_ID STREQUAL "IronPython")
+  message (FATAL_ERROR "Erroneous interpreter ID (${Python2_INTERPRETER_ID})")
+endif()
+
 if (NOT Python2_Compiler_FOUND)
   message (FATAL_ERROR "Fail to found Python 2 Compiler")
 endif()