Compilation failure passing zero_t through assertions

[mlbrooks]

forall( T | { void helper(T); } )
void wrapper( T x ) {
    helper(x);
}

void helper( zero_t ) { printf("zero_t overload\n"); }
void helper( one_t )  { printf("one_t overload\n"); }
void helper( int x )  { printf("int overload, value %d\n", x); }

int main() {
                                #ifndef SUPPRESS_AT_ISSUE_COMPILE_ERROR
    wrapper( 0 );
                                #endif

    wrapper( 1 );
    wrapper( (int) 0 );
    wrapper( (int) 1 );
}

/*
$cfa x.cfa; ./a.out
ACTUAL: Unintelligible error message from GCC blaming the `wrapper(0)` call
EXPECTED: compiles and runs with output:
    zero_t overload
    one_t overload
    int overload, value 0
    int overload, value 1

$cfa x.cfa -DSUPPRESS_AT_ISSUE_COMPILE_ERROR; ./a.out
ACTUAL, EXPECTED: compiles and runs with output:
    one_t overload
    int overload, value 0
    int overload, value 1

Diagnostic:
$cfa x.cfa -CFA -XCFA,-p | grep -F '(void)(0=0)'
ACTUAL: Found
EXPECTED: uh... No.

*/

There is an impact on a programmer using new arrays, when trying to index into a higher-dimensional array using a hardcoded 0 as an index. The repro isn't runnable on the currently-committed source. I'll put the repro here, once the change required to reach the issue is committed.