[Bug 1001915] New: Invalid assert definition

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http://bugs.ecos.sourceware.org/show_bug.cgi?id=1001915

            Bug ID: 1001915
           Summary: Invalid assert definition
           Product: eCos
           Version: 3.0
            Target: All
  Architecture/Host All
                OS:
            Status: UNCONFIRMED
          Severity: major
          Priority: low
         Component: POSIX
          Assignee: unassigned@bugs.ecos.sourceware.org
          Reporter: jsetoain@ucm.es
                CC: ecos-bugs@ecos.sourceware.org

According to ISO C, the assert macro must be an expression but it is defined as
an statement (do { } while(0)). This definition causes trouble in several
situation where "assert" is used as an expression.

From:

http://pubs.opengroup.org/onlinepubs/9699919799/functions/assert.html

"The assert() macro shall insert diagnostics into programs; it shall expand to
a void expression."

Right now it is defined as follows:

# define assert( __bool )                                                 \
    do {                                                                  \
        if (0 == (__bool)) {                                              \
            fprintf( stderr, "User assertion failed: \"%s\", at %s:%d\n", \
                         #__bool, __FILE__, __LINE__);                    \
            abort();                                                      \
        }                                                                 \
    } while(0)

I propose changing it to something like this:

# define assert(__bool)                          \
  ((__bool)                                      \
   ? (void)(0)                                   \
   : assert_failed(#__bool, __FILE__, __LINE__)

And then define assert_failed as something like:

void assert_failed(const char* assertion, const char* file, const char* line )
{
    fprintf( stderr, "User assertion failed: \"%s\", at %s:%d\n",
                  assertion, file, line );
    abort();
}

This way, assert always evaluates to a void expression, as demanded by the
standard.

(PS: The whole fix would take changes in other macros, I'm just illustrating
the problem and the solution).

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