Merge pull request #572 from m-holger/const

Add build option for qpdf CI

setup.py

@@ -23,6 +23,7 @@
 extra_library_dirs = []
 qpdf_source_tree = environ.get('QPDF_SOURCE_TREE', '')
 qpdf_build_libdir = environ.get('QPDF_BUILD_LIBDIR', '')
+qpdf_future = environ.get('QPDF_FUTURE', '')
 
 if qpdf_source_tree:
     # Point this to qpdf source tree built with shared libraries
@@ -69,6 +70,9 @@
     if extra_path and not exists(extra_path):
         raise FileNotFoundError(extra_path)
 
+macros = [('POINTERHOLDER_TRANSITION', '4')]
+if qpdf_future:
+    macros.append(('QPDF_FUTURE', 'True'))
 # Use cast because mypy has trouble seeing Pybind11Extension is a subclass of
 # Extension.
 extmodule: Extension = cast(
@@ -81,7 +85,7 @@
             # Path to pybind11 headers
             *extra_includes,
         ],
-        define_macros=[('POINTERHOLDER_TRANSITION', '4')],
+        define_macros=macros,
         library_dirs=[*extra_library_dirs],
         libraries=['qpdf'],
         cxx_std=17,