common: add storage-class attribute declarations in colorprocs.h

Towards https://gitlab.com/graphviz/graphviz/-/issues/2058.

diff --git a/lib/common/colorprocs.h b/lib/common/colorprocs.h
index fcf959928b51f8af5d8d0acfe0745992653ae611..bb0db31dd7be3470bdb820437ef932982a856c56 100644 (file)
--- a/lib/common/colorprocs.h
+++ b/lib/common/colorprocs.h
@@ -18,9 +18,23 @@
 extern "C" {
 #endif
 
-extern void setColorScheme (char* s);
-extern int colorxlate(char *str, gvcolor_t * color, color_type_t target_type);
-extern char *canontoken(char *str);
+#ifdef GVDLL
+#ifdef GVC_EXPORTS
+#define COLORPROCS_API __declspec(dllexport)
+#else
+#define COLORPROCS_API __declspec(dllimport)
+#endif
+#endif
+
+#ifndef COLORPROCS_API
+#define COLORPROCS_API /* nothing */
+#endif
+
+COLORPROCS_API void setColorScheme (char* s);
+COLORPROCS_API int colorxlate(char *str, gvcolor_t * color, color_type_t target_type);
+COLORPROCS_API char *canontoken(char *str);
+
+#undef COLORPROCS_API
 
 #ifdef __cplusplus
 }