"comma at end of enumerator list" error due to macros in libqof

[Tim M]

Hello,

Per my previous email I am looking at compiler warnings/errors and I
found an interesting one for which I could use some advice.  During
make, libqof came up with a fairly large number of errors, including
quite a few "comma at end of enumerator list" errors.  Some of the
errors were quite simple to fix because they were simple enum lists
with a comma after the last enum item.  Of course, remove the extra
comma and voila - no more error.

It took me a little time to decipher the same compiler error for this
line, however:

   DEFINE_ENUM (QofLogLevel, LOG_LEVEL_LIST)

After a little research, I found that basically, the enum list is
defined in a macro:

   #define LOG_LEVEL_LIST(_) \
     _(QOF_LOG_FATAL,   = G_LOG_LEVEL_ERROR)   \
     _(QOF_LOG_ERROR,   = G_LOG_LEVEL_CRITICAL)   \
     _(QOF_LOG_WARNING, = G_LOG_LEVEL_WARNING) \
     _(QOF_LOG_MESSAGE, = G_LOG_LEVEL_MESSAGE) \
     _(QOF_LOG_INFO,    = G_LOG_LEVEL_INFO)    \
     _(QOF_LOG_DEBUG,   = G_LOG_LEVEL_DEBUG)

The DEFINE_ENUM macro then looks like this:

   #define DEFINE_ENUM(name, list)          \
       typedef enum {                       \
           list(ENUM_BODY)                  \
       }name;

So DEFINE_ENUM in turn calls LOG_LEVEL_LIST(ENUM_BODY).  ENUM_BODY
looks like this:

   #define ENUM_BODY(name, value)           \
       name value,

ENUM_BODY then expands to "name value," for every entry in
LOG_LEVEL_LIST. This then causes the "comma at end of enumerator list"
error mentioned at top because the enum generated by this macro
combination always has a comma after the last entry:

   typedef enum {
     QOF_LOG_FATAL    = G_LOG_LEVEL_ERROR,
     QOF_LOG_ERROR    = G_LOG_LEVEL_CRITICAL,
     QOF_LOG_WARNING  = G_LOG_LEVEL_WARNING,
     QOF_LOG_MESSAGE  = G_LOG_LEVEL_MESSAGE,
     QOF_LOG_INFO     = G_LOG_LEVEL_INFO,
     QOF_LOG_DEBUG    = G_LOG_LEVEL_DEBUG,
   }QofLogLevel;


I can remove the comma from the ENUM_BODY and instead put it in the
LOG_LEVEL_LIST define like this:

   #define ENUM_BODY(name, value)           \
       name value

   #define LOG_LEVEL_LIST(_) \
     _(QOF_LOG_FATAL,   = G_LOG_LEVEL_ERROR),   \
     _(QOF_LOG_ERROR,   = G_LOG_LEVEL_CRITICAL),   \
     _(QOF_LOG_WARNING, = G_LOG_LEVEL_WARNING), \
     _(QOF_LOG_MESSAGE, = G_LOG_LEVEL_MESSAGE), \
     _(QOF_LOG_INFO,    = G_LOG_LEVEL_INFO),    \
     _(QOF_LOG_DEBUG,   = G_LOG_LEVEL_DEBUG)

This change prevents the make warning/error, but after making this
change Eclipse then reports a syntax error at the DEFINE_ENUM
(QofLogLevel, LOG_LEVEL_LIST) line (qoflog.h, line 102), and will no
longer explore the macro expansion.  I'm not sure then if this is
actually a syntax error (since the compiler does not throw any errors
or warnings) or a bug in Eclipse, but having a macro for such a simple
enum is a bit of a headache.

These macros are used throughout gnucash in a few different places so
I am wary of simply tossing out the DEFINE_ENUM and related macros
completely and replacing them with explicit typedefs since the macros
seem to have at least some usefulness to them, so it seems like a less
invasive fix is needed.  I am not sure what the best solution is other
than the one above which causes the Eclipse error.  At the moment I
don't have any better ideas and it is quite late so I must return to
this later.  There are other similar macros in libqof which seem to
share this structure so I expect to see errors from the other macros
as well at some point.  Any suggestions?

Thanks,
-Tim