1375 – CTFE fails for null strings and arrays

Neither of the if's compile:
int foo()
{
 char[] s;
 if (s)
 {
 }
 if (s == null)
 {
 }
 if (s is null)
 {
 }
 if (s == "")
 {
 }
 if (s.length)
 {
 }
 return 0;
}
void main()
{
	static x = foo();
}
If s is initialized to a literal, only the last two if's compile successfully.

When filing bugs, please include the error messages rather than merely stating that something doesn't compile.
bz1375.d(30): Error: cannot evaluate foo() at compile time

I wish the error message was informative enough to be worth writing. Anyway, thanks for pointing that out.

Another example of probably same bug:
char[] copy(char[] x)
{
 char[] ret;
 foreach(c; x) {
 ret ~= c; 
 }
 return ret;
}
pragma(msg, copy(``));
Error:
test_ext.d(83): pragma msg string expected for message, not 'null'
Can work around by changing 
 char[] ret;
to 
 char[] ret = ``;

This works for me in 1.039.

This works in DMD2.027 and DMD1.042.