FindPython: Adds control over artifact names to search

Fixes: #21371

2 files changed, 78 insertions, 0 deletions

diff --git a/Tests/FindPython/CMakeLists.txt b/Tests/FindPython/CMakeLists.txt
index 44484c3..520ba9e 100644
--- a/Tests/FindPython/CMakeLists.txt
+++ b/Tests/FindPython/CMakeLists.txt
@@ -451,6 +451,18 @@ if(CMake_TEST_FindPython)
       --test-command ${CMAKE_CTEST_COMMAND} -V -C $<CONFIGURATION>
       )
   endif()
+
+  if (CMAKE_SYSTEM_NAME STREQUAL "Linux")
+    add_test(NAME FindPython.UnversionedNames COMMAND
+      ${CMAKE_CTEST_COMMAND} -C $<CONFIGURATION>
+      --build-and-test
+      "${CMake_SOURCE_DIR}/Tests/FindPython/UnversionedNames"
+      "${CMake_BINARY_DIR}/Tests/FindPython/UnversionedNames"
+      ${build_generator_args}
+      --build-project UnversionedNames
+      --build-options ${build_options}
+    )
+  endif()
 endif()
 
 if(CMake_TEST_FindPython_NumPy)
diff --git a/Tests/FindPython/UnversionedNames/CMakeLists.txt b/Tests/FindPython/UnversionedNames/CMakeLists.txt
new file mode 100644
index 0000000..597bd4e
--- /dev/null
+++ b/Tests/FindPython/UnversionedNames/CMakeLists.txt
@@ -0,0 +1,66 @@
+cmake_minimum_required(VERSION 3.19...3.20)
+
+project(UnversionedNames LANGUAGES NONE)
+
+# check if it is possible to find python with a generic name
+find_program(UNVERSIONED_Python3 NAMES python3)
+
+if (NOT UNVERSIONED_Python3)
+  # no generic name available
+  # test cannot be done
+  return()
+endif()
+
+# search with default configuration
+find_package(Python3 REQUIRED COMPONENTS Interpreter)
+
+if (Python3_EXECUTABLE STREQUAL UNVERSIONED_Python3)
+  # default configuration pick-up the generic name
+  # test cannot be completed
+  return()
+endif()
+
+unset(Python3_EXECUTABLE)
+# Force now to search first for  generic name
+set(Python3_FIND_UNVERSIONED_NAMES FIRST)
+
+find_package(Python3 REQUIRED COMPONENTS Interpreter)
+
+if (NOT Python3_EXECUTABLE STREQUAL UNVERSIONED_Python3)
+  message(SEND_ERROR "Found unexpected interpreter ${Python3_EXECUTABLE} instead of ${UNVERSIONED_Python3}")
+endif()
+
+# To check value 'NEVER", creates  directory holding a symlink to the generic name
+file(REMOVE_RECURSE "${CMAKE_CURRENT_BINARY_DIR}/bin")
+file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/bin")
+file(CREATE_LINK "${UNVERSIONED_Python3}" "${CMAKE_CURRENT_BINARY_DIR}/bin/python3" SYMBOLIC)
+
+unset(Python3_EXECUTABLE)
+set(Python3_FIND_UNVERSIONED_NAMES FIRST)
+set(Python3_ROOT_DIR "${CMAKE_CURRENT_BINARY_DIR}")
+# First search: generic name must be found
+find_package(Python3 REQUIRED COMPONENTS Interpreter)
+
+if (NOT Python3_EXECUTABLE STREQUAL "${CMAKE_CURRENT_BINARY_DIR}/bin/python3")
+  message(FATAL_ERROR "Found unexpected interpreter ${Python3_EXECUTABLE} instead of ${CMAKE_CURRENT_BINARY_DIR}/bin/python3")
+endif()
+
+unset(Python3_EXECUTABLE)
+set(Python3_FIND_UNVERSIONED_NAMES LAST)
+
+# Second search: generic name must be found
+find_package(Python3 REQUIRED COMPONENTS Interpreter)
+
+if (NOT Python3_EXECUTABLE STREQUAL "${CMAKE_CURRENT_BINARY_DIR}/bin/python3")
+  message(FATAL_ERROR "Found unexpected interpreter ${Python3_EXECUTABLE} instead of ${CMAKE_CURRENT_BINARY_DIR}/bin/python3")
+endif()
+
+unset(Python3_EXECUTABLE)
+set(Python3_FIND_UNVERSIONED_NAMES NEVER)
+
+# Third search: generic name must NOT be found
+find_package(Python3 REQUIRED COMPONENTS Interpreter)
+
+if (Python3_EXECUTABLE STREQUAL "${CMAKE_CURRENT_BINARY_DIR}/bin/python3")
+  message(FATAL_ERROR "Found unexpected interpreter ${Python3_EXECUTABLE}")
+endif()