id	summary	reporter	owner	description	type	status	priority	component	version	resolution	keywords	cc
315	Peculiar trait syntax neither rejected nor supported	mlbrooks		"Consider this basic, working, program with a trait.
{{{
forall( T & )
trait has_global {
    T * global;
};

forall( T & | has_global(T) )
void f( T & parm ) {
    printf(""f: global @ %p; parm @ %p\n"", global, & parm );
}

int main() {
    float x;
    float * global = & x;
    f(x);
}
}}}

Actual and expected: output like:
{{{
f: global @ 0x7fffffffde88; parm @ 0x7fffffffde88
}}}

Now suppose the programmer instead made this mistake, or curious choice:
{{{
forall( T & | { T * global; } )
trait has_global {};
}}}

Actual:  error: duplicate object definition for global: pointer to instance of type T (not function type)

Expected:  one of:
- error like: a trait's forall cannot introduce bare assertions, put new declarations in the trait's body, or
- same as working version

This mistake came up naturally, when trying to refactor a more complex trait, turning
{{{
forall( T & | IS_RESUMPTION_EXCEPTION(CoroutineCancelled(T)) )
trait is_coroutine {
        void main(T & this);
        coroutine$ * get_coroutine(T & this);
};
forall( T & | is_coroutine(T) | { EHM_DEFAULT_VTABLE(CoroutineCancelled(T)); } )
void prime(T & cor);
}}}
into
{{{
forall( T & | IS_RESUMPTION_EXCEPTION(CoroutineCancelled(T)) )
trait is_coroutine {
        void main(T & this);
        coroutine$ * get_coroutine(T & this);
        EHM_DEFAULT_VTABLE(CoroutineCancelled(T));
};
forall( T & | is_coroutine(T) )
void prime(T & cor);
}}}
but mistakenly giving
{{{
forall( T & | IS_RESUMPTION_EXCEPTION(CoroutineCancelled(T)) | { EHM_DEFAULT_VTABLE(CoroutineCancelled(T)); } )
trait is_coroutine {
        void main(T & this);
        coroutine$ * get_coroutine(T & this);
};
}}}

"	defect	new	minor	cfa-cc	1.0		trait syntax