[libxml2] Simplify xmlexports.h

[Nick Wellnhofer <nwellnhof src gnome org>]

commit acdc2ff3607fe003c2febc25f28954146b3c1636
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Thu Jun 4 23:02:08 2020 +0200

    Simplify xmlexports.h
    
    All the compiler switches essentially set the same macros. The only
    exception was MSVC which omitted the "extern" keyword for exported
    variables. This in turn broke clang-cl.
    
    This commit rewrites and simplifies the whole header.
    
    Closes #163.

 include/libxml/xmlexports.h | 154 +++++++++++---------------------------------
 1 file changed, 39 insertions(+), 115 deletions(-)
---
diff --git a/include/libxml/xmlexports.h b/include/libxml/xmlexports.h
index f03af0d0..aceede5e 100644
--- a/include/libxml/xmlexports.h
+++ b/include/libxml/xmlexports.h
@@ -3,43 +3,46 @@
  * Description: macros for marking symbols as exportable/importable.
  *
  * Copy: See Copyright for the status of this software.
- *
- * Author: Igor Zlatovic <igor zlatkovic com>
  */
 
 #ifndef __XML_EXPORTS_H__
 #define __XML_EXPORTS_H__
 
-/**
- * XMLPUBFUN, XMLPUBVAR, XMLCALL
- *
- * Macros which declare an exportable function, an exportable variable and
- * the calling convention used for functions.
- *
- * Please use an extra block for every platform/compiler combination when
- * modifying this, rather than overlong #ifdef lines. This helps
- * readability as well as the fact that different compilers on the same
- * platform might need different definitions.
- */
+#if defined(_WIN32) || defined(__CYGWIN__)
+/** DOC_DISABLE */
+
+#ifdef LIBXML_STATIC
+  #define XMLPUBLIC
+#elif defined(IN_LIBXML)
+  #define XMLPUBLIC __declspec(dllexport)
+#else
+  #define XMLPUBLIC __declspec(dllimport)
+#endif
+
+#if defined(LIBXML_FASTCALL)
+  #define XMLCALL __fastcall
+#else
+  #define XMLCALL __cdecl
+#endif
+#define XMLCDECL __cdecl
+
+/** DOC_ENABLE */
+#else /* not Windows */
 
 /**
- * XMLPUBFUN:
- *
- * Macros which declare an exportable function
- */
-#define XMLPUBFUN
-/**
- * XMLPUBVAR:
+ * XMLPUBLIC:
  *
- * Macros which declare an exportable variable
+ * Macro which declares a public symbol
  */
-#define XMLPUBVAR extern
+#define XMLPUBLIC
+
 /**
  * XMLCALL:
  *
- * Macros which declare the called convention for exported functions
+ * Macro which declares the calling convention for exported functions
  */
 #define XMLCALL
+
 /**
  * XMLCDECL:
  *
@@ -48,100 +51,21 @@
  */
 #define XMLCDECL
 
-/** DOC_DISABLE */
-
-/* Windows platform with MS compiler */
-#if defined(_WIN32) && defined(_MSC_VER)
-  #undef XMLPUBFUN
-  #undef XMLPUBVAR
-  #undef XMLCALL
-  #undef XMLCDECL
-  #if defined(IN_LIBXML) && !defined(LIBXML_STATIC)
-    #define XMLPUBFUN __declspec(dllexport)
-    #define XMLPUBVAR __declspec(dllexport)
-  #else
-    #define XMLPUBFUN
-    #if !defined(LIBXML_STATIC)
-      #define XMLPUBVAR __declspec(dllimport) extern
-    #else
-      #define XMLPUBVAR extern
-    #endif
-  #endif
-  #if defined(LIBXML_FASTCALL)
-    #define XMLCALL __fastcall
-  #else
-    #define XMLCALL __cdecl
-  #endif
-  #define XMLCDECL __cdecl
-#endif
+#endif /* platform switch */
 
-/* Windows platform with Borland compiler */
-#if defined(_WIN32) && defined(__BORLANDC__)
-  #undef XMLPUBFUN
-  #undef XMLPUBVAR
-  #undef XMLCALL
-  #undef XMLCDECL
-  #if defined(IN_LIBXML) && !defined(LIBXML_STATIC)
-    #define XMLPUBFUN __declspec(dllexport)
-    #define XMLPUBVAR __declspec(dllexport) extern
-  #else
-    #define XMLPUBFUN
-    #if !defined(LIBXML_STATIC)
-      #define XMLPUBVAR __declspec(dllimport) extern
-    #else
-      #define XMLPUBVAR extern
-    #endif
-  #endif
-  #define XMLCALL __cdecl
-  #define XMLCDECL __cdecl
-#endif
-
-/* Windows platform with GNU compiler (Mingw) */
-#if defined(_WIN32) && defined(__MINGW32__)
-  #undef XMLPUBFUN
-  #undef XMLPUBVAR
-  #undef XMLCALL
-  #undef XMLCDECL
-  /*
-   * if defined(IN_LIBXML) this raises problems on mingw with msys
-   * _imp__xmlFree listed as missing. Try to workaround the problem
-   * by also making that declaration when compiling client code.
-   */
-  #if defined(IN_LIBXML) && !defined(LIBXML_STATIC)
-    #define XMLPUBFUN __declspec(dllexport)
-    #define XMLPUBVAR __declspec(dllexport) extern
-  #else
-    #define XMLPUBFUN
-    #if !defined(LIBXML_STATIC)
-      #define XMLPUBVAR __declspec(dllimport) extern
-    #else
-      #define XMLPUBVAR extern
-    #endif
-  #endif
-  #define XMLCALL __cdecl
-  #define XMLCDECL __cdecl
-#endif
+/*
+ * XMLPUBFUN:
+ *
+ * Macro which declares an exportable function
+ */
+#define XMLPUBFUN XMLPUBLIC
 
-/* Cygwin platform (does not define _WIN32), GNU compiler */
-#if defined(__CYGWIN__)
-  #undef XMLPUBFUN
-  #undef XMLPUBVAR
-  #undef XMLCALL
-  #undef XMLCDECL
-  #if defined(IN_LIBXML) && !defined(LIBXML_STATIC)
-    #define XMLPUBFUN __declspec(dllexport)
-    #define XMLPUBVAR __declspec(dllexport)
-  #else
-    #define XMLPUBFUN
-    #if !defined(LIBXML_STATIC)
-      #define XMLPUBVAR __declspec(dllimport) extern
-    #else
-      #define XMLPUBVAR extern
-    #endif
-  #endif
-  #define XMLCALL __cdecl
-  #define XMLCDECL __cdecl
-#endif
+/**
+ * XMLPUBVAR:
+ *
+ * Macro which declares an exportable variable
+ */
+#define XMLPUBVAR XMLPUBLIC extern
 
 /* Compatibility */
 #if !defined(LIBXML_DLL_IMPORT)