🐛 fix error loading bug in MSVC version

doc/tutorial.md

@@ -593,7 +593,7 @@ module_func_info func_tbl[] = {
 // the reason why using this way to get function pointer
 // is because `var` has constructors, which is not compatiable in C
 // so "extern "C" var fib" may get compilation warnings
-extern "C" module_func_info* get() {
+NASAL_EXTERN module_func_info* get() {
     return func_tbl;
 }
 ```

doc/tutorial_zh.md

@@ -574,7 +574,7 @@ module_func_info func_tbl[] = {
 // 之所以用这种方式来获取函数指针, 是因为`var`是有构造函数的
 // 有构造函数的类型作为返回值, 和C是不兼容的, 这导致
 // 类似 "extern "C" var fib" 的写法会得到编译错误
-extern "C" module_func_info* get() {
+NASAL_EXTERN module_func_info* get() {
     return func_tbl;
 }
 ```

module/fib.cpp

@@ -115,7 +115,7 @@ module_func_info func_tbl[] = {
 
 }
 
-extern "C" module_func_info* get() {
+NASAL_EXTERN module_func_info* get() {
     return fib_module::func_tbl;
 }
 

module/json.cpp

@@ -371,7 +371,7 @@ module_func_info func_tbl[] = {
     {nullptr, nullptr}
 };
 
-extern "C" module_func_info* get() {
+NASAL_EXTERN module_func_info* get() {
     return func_tbl;
 }
 

module/keyboard.cpp

@@ -106,7 +106,7 @@ module_func_info func_tbl[] = {
     {nullptr, nullptr}
 };
 
-extern "C" module_func_info* get() {
+NASAL_EXTERN module_func_info* get() {
     return func_tbl;
 }
 

module/matrix.cpp

@@ -295,7 +295,7 @@ module_func_info func_tbl[] = {
     {nullptr, nullptr}
 };
 
-extern "C" module_func_info* get() {
+NASAL_EXTERN module_func_info* get() {
     return func_tbl;
 }
 

module/nasocket.cpp

@@ -256,7 +256,7 @@ module_func_info func_tbl[] = {
     {nullptr, nullptr}
 };
 
-extern "C" module_func_info* get() {
+NASAL_EXTERN module_func_info* get() {
     return func_tbl;
 }
 

src/nasal_gc.h

@@ -124,4 +124,13 @@ struct module_func_info {
 // module function "get" type
 typedef module_func_info* (*get_func_ptr)();
 
+
+// avoid error loading function bug in MSVC version nasal.exe
+#ifdef _MSC_VER
+    // and fuck MSVC again
+    #define NASAL_EXTERN extern "C" __declspec(dllexport)
+#else
+    #define NASAL_EXTERN extern "C"
+#endif
+
 }