From c7960385bec6bee443f459f7b1905e007d4ec993 Mon Sep 17 00:00:00 2001
From: Saran Tunyasuvunakool <stunya@google.com>
Date: Fri, 28 Oct 2022 08:41:05 -0700
Subject: [PATCH] Declare DllMain as `extern "C"`.

Fixes #550.

PiperOrigin-RevId: 484540205
Change-Id: I3915f65f1ae6ab3a93118b9d747b5c09d9abe872
---
 include/mujoco/mjplugin.h                | 24 ++++++++++++++++--------
 unity/Runtime/Bindings/MujocoBindings.cs |  1 +
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/include/mujoco/mjplugin.h b/include/mujoco/mjplugin.h
index 1ce1b5e5..eccf9d22 100644
--- a/include/mujoco/mjplugin.h
+++ b/include/mujoco/mjplugin.h
@@ -72,15 +72,23 @@ typedef struct mjpPlugin_ mjpPlugin;
 #define mjDLLMAIN DllMain
 #endif
 
+#if !defined(mjEXTERNC)
+#if defined(__cplusplus)
+#define mjEXTERNC extern "C"
+#else
+#define mjEXTERNC
+#endif  // defined(__cplusplus)
+#endif  // !defined(mjEXTERNC)
+
 // NOLINTBEGIN(runtime/int)
-#define mjPLUGIN_DYNAMIC_LIBRARY_INIT                                                 \
-  static void _mjplugin_dllmain(void);                                                \
-  static int __stdcall mjDLLMAIN(void* hinst, unsigned long reason, void* reserved) { \
-    if (reason == 1) {                                                                \
-      _mjplugin_dllmain();                                                            \
-    }                                                                                 \
-    return 1;                                                                         \
-  }                                                                                   \
+#define mjPLUGIN_DYNAMIC_LIBRARY_INIT                                                     \
+  static void _mjplugin_dllmain(void);                                                    \
+  mjEXTERNC int __stdcall mjDLLMAIN(void* hinst, unsigned long reason, void* reserved) {  \
+    if (reason == 1) {                                                                    \
+      _mjplugin_dllmain();                                                                \
+    }                                                                                     \
+    return 1;                                                                             \
+  }                                                                                       \
   static void _mjplugin_dllmain(void)
 // NOLINTEND(runtime/int)
 
diff --git a/unity/Runtime/Bindings/MujocoBindings.cs b/unity/Runtime/Bindings/MujocoBindings.cs
index 47b8c204..940e6624 100644
--- a/unity/Runtime/Bindings/MujocoBindings.cs
+++ b/unity/Runtime/Bindings/MujocoBindings.cs
@@ -50,6 +50,7 @@ public const int mjNREF = 2;
 public const int mjNIMP = 5;
 public const int mjNSOLVER = 1000;
 public const bool THIRD_PARTY_MUJOCO_INCLUDE_MJPLUGIN_H_ = true;
+public const bool mjEXTERNC = true;
 public const bool THIRD_PARTY_MUJOCO_MJRENDER_H_ = true;
 public const int mjNAUX = 10;
 public const int mjMAXTEXTURE = 1000;