compile time output

[Sergey Gromov]

Tue, 20 Jan 2009 16:36:09 +0100, Trass3r wrote:

> Is there any way to output information at compile time other than 
> pragma(msg?
> pragma is driving me crazy, the following doesn't work:
> 
> auto members = __traits(allMembers, typeof(this));
> foreach(m; members)
> {
> 	pragma(msg, m);
> }
> 
> -> Error: string expected for message, not 'm'
> 
> Though the docs clearly state:
> allMembers: "An array of string literals is returned"
> Also checked that, m is of type invariant(char)[].
> 
> Any ideas? -.-

Weird.  The following code does not compile:

class Cls
{
  int bar;
  char[] baz;
}
string foo()
{
  auto members = __traits(allMembers, Cls);
  return "";
}
pragma(msg, foo());

>dmd -c test.d
test.d(11): Error: cannot evaluate foo() at compile time
test.d(11): pragma msg string expected for message, not 'foo()'

Comment out the traits and it compiles.  Traits are supposed to be
compile-time.  How's that possible for them to prevent compile-time
evaluation?