Set Py_DEBUG flag in sysconfig

Author: XuehaiPan

Lib/sysconfig/__init__.py

@@ -401,7 +401,7 @@ def _init_non_posix(vars):
     vars['BINLIBDEST'] = get_path('platstdlib')
     vars['INCLUDEPY'] = get_path('include')
 
-    # Add EXT_SUFFIX, SOABI, ABIFLAGS, and Py_GIL_DISABLED
+    # Add EXT_SUFFIX, SOABI, ABIFLAGS, Py_DEBUG, and Py_GIL_DISABLED
     # NOTE: ABIFLAGS is only an emulated value. It is not present during build
     #       on Windows. sys.abiflags is absent on Windows and `vars['abiflags']
     #       is already widely used to calculate paths. vars['abiflags'] should

Modules/_sysconfig.c

@@ -64,8 +64,15 @@ _sysconfig_config_vars_impl(PyObject *module)
 #  ifdef Py_GIL_DISABLED
                          "t"
 #  endif
-#  ifdef _DEBUG
+#  ifdef Py_DEBUG
+#    ifndef _DEBUG
+#      error "_DEBUG not defined while Py_DEBUG is defined on Windows"
+#    endif
                          "d"
+#  else
+#    ifdef _DEBUG
+#      error "_DEBUG defined while Py_DEBUG is not defined on Windows"
+#    endif
 #  endif
                          "")
         < 0) {
@@ -84,6 +91,16 @@ _sysconfig_config_vars_impl(PyObject *module)
         return NULL;
     }
 
+#ifdef Py_DEBUG
+    PyObject *py_debug = _PyLong_GetOne();
+#else
+    PyObject *py_debug = _PyLong_GetZero();
+#endif
+    if (PyDict_SetItemString(config, "Py_DEBUG", py_debug) < 0) {
+        Py_DECREF(config);
+        return NULL;
+    }
+
     return config;
 }