From cc2c016f3432d9d4f7daf768c790075a204895c0 Mon Sep 17 00:00:00 2001
From: Andrey Volk <andywolk@gmail.com>
Date: Wed, 29 Jul 2026 20:30:20 +0300
Subject: [PATCH] Fix error C2020: 'parms': 'struct' member redefinition

  <windows.h> (shared/minwindef.h) defines the legacy 16 bit memory model
  keywords "near" and "far" as empty macros. In any translation unit that
  includes it ahead of spandsp/expose.h, that strips the names from the near
  and far members of struct v150_1_state_s:

      struct { v150_1_near_far_t parms; ... } ;   /* was } near; */
      struct { v150_1_near_far_t parms; ... } ;   /* was } far;  */

  MSVC then treats both as anonymous structs and flattens their members into
  the enclosing struct, where the two "parms" members collide. The error names
  "parms" rather than near/far because those tokens are gone before the
  compiler sees them.

  Undefine both macros around the struct in private/v150_1.h, restoring them
  with #pragma pop_macro at the end of the header. private/v150_1.h is an
  installed header, so it must not leave a consumer's macro state altered.
  v150_1.c refers to the members by name and is the only file that does, so it
  undefines the macros locally after its includes.
---
 src/spandsp/private/v150_1.h | 19 +++++++++++++++++++
 src/v150_1.c                 |  8 ++++++++
 2 files changed, 27 insertions(+)

diff --git a/src/spandsp/private/v150_1.h b/src/spandsp/private/v150_1.h
index 68c60767..cd658678 100644
--- a/src/spandsp/private/v150_1.h
+++ b/src/spandsp/private/v150_1.h
@@ -26,6 +26,20 @@
 #if !defined(_SPANDSP_PRIVATE_V150_1_H_)
 #define _SPANDSP_PRIVATE_V150_1_H_
 
+#if defined(_WIN32)
+/* <windows.h> (minwindef.h) defines the legacy 16 bit memory model keywords
+   "near" and "far" as empty macros. Left in place, they strip the names from
+   the near and far members of v150_1_state_s, making them anonymous structs.
+   MSVC then flattens their contents into the enclosing struct, where the two
+   "parms" members collide (error C2020: 'parms': 'struct' member
+   redefinition). Both macros are restored at the end of this header, so an
+   including application keeps whatever it had. */
+#pragma push_macro("near")
+#pragma push_macro("far")
+#undef near
+#undef far
+#endif
+
 /*
                telephone network
                       ^
@@ -361,5 +375,10 @@ struct v150_1_state_s
     logging_state_t logging;
 };
 
+#if defined(_WIN32)
+#pragma pop_macro("far")
+#pragma pop_macro("near")
+#endif
+
 #endif
 /*- End of file ------------------------------------------------------------*/
diff --git a/src/v150_1.c b/src/v150_1.c
index 03fc64c3..01560b99 100644
--- a/src/v150_1.c
+++ b/src/v150_1.c
@@ -56,6 +56,14 @@
 
 #include "v150_1_local.h"
 
+#if defined(_WIN32)
+/* See the note in spandsp/private/v150_1.h. The near and far members of
+   v150_1_state_t are referenced by name throughout this file, so the
+   <windows.h> macros of those names must not be in effect here. */
+#undef near
+#undef far
+#endif
+
 /* Terminology
 
     V.150.1 has several components. The terms used for these are: