sizeof as a param's usage may leave this param unused

[mlbrooks]

void fred( const char & p ) {
    printf( "%zu\n", sizeof(p) );
}

forall( T * )
void mary( const T & p ) {
    printf( "%zu\n", sizeof(p) );
}

int main() {
    char x = 'a';
    fred(x);
    mary(x);
    return 0;
}

$cfa -Wall -Wextra -Werror test.cfa

Expected: run, print 1 twice
Actual: compile error: unused parameter (mangled name of) p, twice

Note that in -CFA output, the sizeof(p) expressions are rewritten as

• sizeof(const char), within fred
• _sizeof_Y1T, within mary