qga: Clean up unnecessarily dirty casts

qga_vss_fsfreeze() casts error_set_win32() from

    void (*)(Error **, int, ErrorClass, const char *, ...)

to

    void (*)(void **, int, int, const char *, ...)

The result is later called.  Since the two types are not compatible,
the call is undefined behavior.  It works in practice anyway.

However, there's no real need for trickery here.  Clean it up as
follows:

* Declare struct Error, and fix the first parameter.

* Switch to error_setg_win32().  This gets rid of the troublesome
  ErrorClass parameter.  Requires converting error_setg_win32() from
  macro to function, but that's trivially easy, because this is the
  only user of error_set_win32().

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

1 files changed, 2 insertions, 7 deletions

diff --git a/include/qapi/error.h b/include/qapi/error.h
index 34af4e103f..692e01346e 100644
--- a/include/qapi/error.h
+++ b/include/qapi/error.h
@@ -44,8 +44,8 @@ void error_set_errno(Error **errp, int os_error, ErrorClass err_class,
  * printf-style human message, followed by a g_win32_error_message() string if
  * @win32_err is not zero.
  */
-void error_set_win32(Error **errp, int win32_err, ErrorClass err_class,
-                     const char *fmt, ...) GCC_FMT_ATTR(4, 5);
+void error_setg_win32(Error **errp, int win32_err, const char *fmt, ...)
+    GCC_FMT_ATTR(3, 4);
 #endif
 
 /**
@@ -56,11 +56,6 @@ void error_setg(Error **errp, const char *fmt, ...)
 #define error_setg_errno(errp, os_error, fmt, ...) \
     error_set_errno(errp, os_error, ERROR_CLASS_GENERIC_ERROR, \
                     fmt, ## __VA_ARGS__)
-#ifdef _WIN32
-#define error_setg_win32(errp, win32_err, fmt, ...) \
-    error_set_win32(errp, win32_err, ERROR_CLASS_GENERIC_ERROR, \
-                    fmt, ## __VA_ARGS__)
-#endif
 
 /**
  * Helper for open() errors