Require python>=3.11 and cython>=3.1 for limited api support

Author: isuruf

cmake/FindCython.cmake

@@ -24,13 +24,31 @@ IF (CYTHON_BIN)
     else (CYTHON_RESULT EQUAL 0)
         SET(Cython_Compilation_Failed TRUE)
     endif (CYTHON_RESULT EQUAL 0)
+    execute_process(
+        COMMAND ${CYTHON_BIN} --version
+        RESULT_VARIABLE CYTHON_VERSION_RESULT
+        OUTPUT_VARIABLE CYTHON_VERSION_OUTPUT
+        ERROR_VARIABLE CYTHON_VERSION_ERROR
+    )
+    if (CYTHON_VERSION_RESULT EQUAL 0)
+        string(STRIP ${CYTHON_VERSION_OUTPUT} CYTHON_VERSION_OUTPUT)
+        if ("${CYTHON_VERSION_OUTPUT}" MATCHES "Cython version")
+             string(SUBSTRING "${CYTHON_VERSION_OUTPUT}" 15 -1 CYTHON_VERSION)
+        endif ()
+    endif ()
+    message(STATUS "Cython version: ${CYTHON_VERSION}")
 ENDIF (CYTHON_BIN)
 
 
 IF (Cython_FOUND)
     IF (NOT Cython_FIND_QUIETLY)
         MESSAGE(STATUS "Found CYTHON: ${CYTHON_BIN}")
     ENDIF (NOT Cython_FIND_QUIETLY)
+    IF (WITH_PY_LIMITED_API AND "${CYTHON_VERSION}" VERSION_LESS "3.1")
+        MESSAGE(FATAL_ERROR
+            "Your Cython version (${CYTHON_VERSION}) is too old. Please upgrade Cython to 3.1 or newer."
+        )
+    ENDIF ()
 ELSE (Cython_FOUND)
     IF (Cython_FIND_REQUIRED)
         if(Cython_Compilation_Failed)

setup.py

@@ -128,6 +128,8 @@ def cmake_build(self):
         if self.py_limited_api:
             assert self.py_limited_api.startswith("cp3")
             py_ver_minor = int(self.py_limited_api[3:])
+            if py_ver_minor < 11:
+                raise ValueError(f"symengine needs at least cp311 limited API support. Got {self.py_limited_api}")
             h = 3 * 16**6 + py_ver_minor * 16**4
             cmake_cmd.append(f"-DWITH_PY_LIMITED_API={h}")