FindPython: Add version range support

Fixes: #21107

1 files changed, 47 insertions, 5 deletions

diff --git a/Modules/FindPython.cmake b/Modules/FindPython.cmake
index 584f64d3e2..2d13f48162 100644
--- a/Modules/FindPython.cmake
+++ b/Modules/FindPython.cmake
@@ -10,6 +10,10 @@ FindPython
 Find Python interpreter, compiler and development environment (include
 directories and libraries).
 
+When a version is requested, it can be specified as a simple value or as a
+range. For a detailed description of version range usage and capabilities,
+refer to the :command:`find_package` command.
+
 The following components are supported:
 
 * ``Interpreter``: search for Python interpreter.
@@ -387,13 +391,39 @@ module suffix will include the ``Python_SOABI`` value, if any.
 #]=======================================================================]
 
 
-set (_PYTHON_PREFIX Python)
+cmake_policy(PUSH)
+# numbers and boolean constants
+cmake_policy (SET CMP0012 NEW)
 
-if (DEFINED Python_FIND_VERSION)
+
+set (_PYTHON_PREFIX Python)
+unset (_Python_REQUIRED_VERSION_MAJOR)
+unset (_Python_REQUIRED_VERSIONS)
+
+if (Python_FIND_VERSION_RANGE)
+  # compute list of major versions
+  foreach (_Python_MAJOR IN ITEMS 3 2)
+    if (_Python_MAJOR VERSION_GREATER_EQUAL Python_FIND_VERSION_MIN_MAJOR
+        AND ((Python_FIND_VERSION_RANGE_MAX STREQUAL "INCLUDE" AND _Python_MAJOR VERSION_LESS_EQUAL Python_FIND_VERSION_MAX)
+        OR (Python_FIND_VERSION_RANGE_MAX STREQUAL "EXCLUDE" AND _Python_MAJOR VERSION_LESS Python_FIND_VERSION_MAX)))
+      list (APPEND _Python_REQUIRED_VERSIONS ${_Python_MAJOR})
+    endif()
+  endforeach()
+  list (LENGTH _Python_REQUIRED_VERSIONS _Python_VERSION_COUNT)
+  if (_Python_VERSION_COUNT EQUAL 0)
+    unset (_Python_REQUIRED_VERSIONS)
+  elseif (_Python_VERSION_COUNT EQUAL 1)
+    set (_Python_REQUIRED_VERSION_MAJOR ${_Python_REQUIRED_VERSIONS})
+  endif()
+elseif (DEFINED Python_FIND_VERSION)
   set (_Python_REQUIRED_VERSION_MAJOR ${Python_FIND_VERSION_MAJOR})
+else()
+  set (_Python_REQUIRED_VERSIONS 3 2)
+endif()
 
+if (_Python_REQUIRED_VERSION_MAJOR)
   include (${CMAKE_CURRENT_LIST_DIR}/FindPython/Support.cmake)
-else()
+elseif (_Python_REQUIRED_VERSIONS)
   # iterate over versions in quiet and NOT required modes to avoid multiple
   # "Found" messages and prematurally failure.
   set (_Python_QUIETLY ${Python_FIND_QUIETLY})
@@ -401,7 +431,6 @@ else()
   set (Python_FIND_QUIETLY TRUE)
   set (Python_FIND_REQUIRED FALSE)
 
-  set (_Python_REQUIRED_VERSIONS 3 2)
   set (_Python_REQUIRED_VERSION_LAST 2)
 
   unset (_Python_INPUT_VARS)
@@ -435,10 +464,21 @@ else()
   set (Python_FIND_REQUIRED ${_Python_REQUIRED})
   if (Python_FIND_REQUIRED OR NOT Python_FIND_QUIETLY)
     # call again validation command to get "Found" or error message
-    find_package_handle_standard_args (Python HANDLE_COMPONENTS
+    find_package_handle_standard_args (Python HANDLE_COMPONENTS HANDLE_VERSION_RANGE
                                               REQUIRED_VARS ${_Python_REQUIRED_VARS}
                                               VERSION_VAR Python_VERSION)
   endif()
+else()
+  # supported versions not in the specified range. Call final check
+  if (NOT Python_FIND_COMPONENTS)
+    set (Python_FIND_COMPONENTS Interpreter)
+    set (Python_FIND_REQUIRED_Interpreter TRUE)
+  endif()
+
+  include (${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
+  find_package_handle_standard_args (Python HANDLE_COMPONENTS HANDLE_VERSION_RANGE
+                                            VERSION_VAR Python_VERSION
+                                            REASON_FAILURE_MESSAGE "Version range specified \"${Python_FIND_VERSION_RANGE}\" does not include supported versions")
 endif()
 
 if (COMMAND __Python_add_library)
@@ -448,3 +488,5 @@ if (COMMAND __Python_add_library)
 endif()
 
 unset (_PYTHON_PREFIX)
+
+cmake_policy(POP)