Move ABIFLAGS definition to C code

Author: XuehaiPan

Lib/sysconfig/__init__.py

@@ -401,7 +401,11 @@ def _init_non_posix(vars):
     vars['BINLIBDEST'] = get_path('platstdlib')
     vars['INCLUDEPY'] = get_path('include')
 
-    # Add EXT_SUFFIX, SOABI, and Py_GIL_DISABLED
+    # Add EXT_SUFFIX, SOABI, ABIFLAGS, and Py_GIL_DISABLED (defined in Modules/_sysconfig.c)
+    # 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
+    #       remain empty string.
     vars.update(_sysconfig.config_vars())
 
     vars['LIBDIR'] = _safe_realpath(os.path.join(get_config_var('installed_base'), 'libs'))
@@ -414,12 +418,6 @@ def _init_non_posix(vars):
     vars['BINDIR'] = os.path.dirname(_safe_realpath(sys.executable))
     vars['TZPATH'] = ''
 
-    abiflags = vars['abi_thread']
-    if vars['EXT_SUFFIX'].endswith('_d.'):
-        abiflags += 'd'
-    # Do not touch lower-cased `abiflags` here.
-    # sys.abiflags is absent on Windows. So vars['abiflags'] should be empty.
-    vars['ABIFLAGS'] = abiflags
 
 #
 # public APIs

Misc/ACKS

@@ -1402,6 +1402,7 @@ Todd R. Palmer
 Juan David Ibáñez Palomar
 Nicola Palumbo
 Jan Palus
+Xuehai Pan
 Yongzhi Pan
 Martin Panter
 Mathias Panzenböck

Modules/_sysconfig.c

@@ -55,6 +55,30 @@ _sysconfig_config_vars_impl(PyObject *module)
         Py_DECREF(config);
         return NULL;
     }
+
+    // On Unix, the `ABIFLAGS` key is defined via a different logic.
+#  ifdef Py_GIL_DISABLED
+#    define _SYSCONFIG_ABI_THREAD "t"
+#  else
+#    define _SYSCONFIG_ABI_THREAD ""
+#  endif
+#  ifdef _DEBUG
+#    define _SYSCONFIG_ABI_DEBUG "d"
+#  else
+#    define _SYSCONFIG_ABI_DEBUG ""
+#  endif
+#  define _SYSCONFIG_ABIFLAGS (_SYSCONFIG_ABI_THREAD _SYSCONFIG_ABI_DEBUG)
+
+    // Emulate `sys.abiflags` value on Unix for Windows. ABIFLAGS here is only
+    // an emulated value. It is not present during build on Windows.
+    if (add_string_value(config, "ABIFLAGS", SYSCONFIG_ABIFLAGS) < 0) {
+        Py_DECREF(config);
+        return NULL;
+    }
+
+#  undef _SYSCONFIG_ABI_THREAD
+#  undef _SYSCONFIG_ABI_DEBUG
+#  undef _SYSCONFIG_ABIFLAGS
 #endif
 
 #ifdef Py_GIL_DISABLED