update: with @nogc @trusted pure this becomes even uglier:


@nogc @trusted pure
void test(int a){
  if(!(a==3)){
    debug{
    char[100]buf; //TODO:make sure big enough
    // would like to use 'auto s=sformat(buf, "a = %s", a);' but not nogc: https://issues.dlang.org/show_bug.cgi?id=13055 
    auto m=snprintf(buf.ptr, buf.length, "a = %d", a);
    assert(m<buf.length && m>0);
    assert(0, buf[0..m]);
    }
    else{
      assert(0);
    }
  }
}


On Sat, Jan 9, 2016 at 11:54 PM, Timothee Cour <thelastmammoth@gmail.com> wrote:
Is there a better way than the example below to have an informative (ie formatted with runtime values) error message inside a nogc function?

@nogc
void test(int a){
  char[100]buf; //TODO:make sure big enough
  //auto s=sformat(buf, "a = %s", a);/// not nogc even though it accepts a buf
  auto m=snprintf(buf.ptr, buf.length, "a = %d", a);
  assert(m<buf.length && m>0);
  assert(a==3, buf[0..m]);
}