From 7a4eb52c813cadfd4c698841a6417c4e048678f1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=90=D0=BB=D0=B5=D0=BA=D1=81=D0=B5=D0=B9?=
 <alexey.pawlow@gmail.com>
Date: Thu, 17 Jun 2021 18:51:39 +0530
Subject: [PATCH 018/N] Add support for stdcall without underscore
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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This is the case used in MINGW

Co-authored-by: Алексей <alexey.pawlow@gmail.com>
---
 Modules/_ctypes/_ctypes.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
index 7f843a2..ff4ec57 100644
--- a/Modules/_ctypes/_ctypes.c
+++ b/Modules/_ctypes/_ctypes.c
@@ -3560,6 +3560,18 @@ static PPROC FindAddress(void *handle, const char *name, PyObject *type)
     mangled_name = alloca(strlen(name) + 1 + 1 + 1 + 3); /* \0 _ @ %d */
     if (!mangled_name)
         return NULL;
+    /* Issue: for stdcall decorated export functions MSVC compiler adds
+     * underscore, but GCC compiler create them without. This is
+     * visible by example for _ctypes_test.pyd module.
+     * As well functions from system libraries are without underscore.
+     * Solutions:
+     * - If a python module is build with gcc option --add-stdcall-alias
+     * the module will contain XXX as alias for function XXX@ as result
+     * first search in this method will succeed.
+     * - Distutil may use compiler to create def-file, to modify it as
+     * add underscore alias and with new def file to create module.
+     * - Or may be just to search for function without underscore.
+     */
     for (i = 0; i < 32; ++i) {
         sprintf(mangled_name, "_%s@%d", name, i*4);
         Py_BEGIN_ALLOW_THREADS
@@ -3567,6 +3579,13 @@ static PPROC FindAddress(void *handle, const char *name, PyObject *type)
         Py_END_ALLOW_THREADS
         if (address)
             return address;
+        /* search for function without underscore as weel */
+        sprintf(mangled_name, "%s@%d", name, i*4);
+        Py_BEGIN_ALLOW_THREADS
+        address = (PPROC)GetProcAddress(handle, mangled_name);
+        Py_END_ALLOW_THREADS
+        if (address)
+            return address;
     }
     return NULL;
 #endif
