does it work like this?

Author: picnixz

Modules/_hashlib/hashlib_buffer.h

@@ -14,7 +14,7 @@
  *
  * The symbol is exported for '_hashlib' and HACL*-based extension modules.
  */
-PyAPI_FUNC(int)
+extern int
 _Py_hashlib_data_argument(PyObject **res, PyObject *data, PyObject *string);
 
 /*
@@ -25,7 +25,7 @@ _Py_hashlib_data_argument(PyObject **res, PyObject *data, PyObject *string);
  *
  * The symbol is exported for '_hashlib' and HACL*-based extension modules.
  */
-PyAPI_FUNC(int)
+extern int
 _Py_hashlib_get_buffer_view(PyObject *obj, Py_buffer *view);
 
 /*

PCbuild/_hashlib.vcxproj

@@ -99,6 +99,7 @@
   </ItemDefinitionGroup>
   <ItemGroup>
     <ClCompile Include="..\Modules\_hashopenssl.c" />
+    <ClCompile Include="..\Modules\_hashlib\hashlib_fetch.c" />
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="..\Modules\_hashlib\hashlib_buffer.h" />

PCbuild/_hashlib.vcxproj.filters

@@ -12,6 +12,9 @@
     <ClCompile Include="..\Modules\_hashopenssl.c">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="..\Modules\_hashlib\hashlib_buffer.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ResourceCompile Include="..\PC\python_nt.rc">

PCbuild/pythoncore.vcxproj

@@ -447,7 +447,6 @@
       <PreprocessorDefinitions>HACL_CAN_COMPILE_VEC128;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <AdditionalOptions>/arch:AVX %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
-    <ClCompile Include="..\Modules\_hashlib\hashlib_buffer.c" />
     <ClInclude Include="..\Modules\_hashlib\hashlib_buffer.h" />
     <ClInclude Include="..\Modules\_hashlib\hashlib_fetch.h" />
     <ClInclude Include="..\Modules\_hashlib\hashlib_mutex.h" />

PCbuild/pythoncore.vcxproj.filters

@@ -980,9 +980,6 @@
     <ClCompile Include="..\Modules\_hacl\Hacl_Streaming_HMAC.c">
       <Filter>Modules</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_hashlib\hashlib_buffer.c">
-      <Filter>Modules\_hashlib</Filter>
-    </ClCompile>
     <ClCompile Include="..\Modules\_heapqmodule.c">
       <Filter>Modules</Filter>
     </ClCompile>