With Github HEAD dmd I get:

$ rdmd --force /tmp/test.d
/tmp/test.d(3): Deprecation: integral promotion not done for ~foo, use '-transition=intpromote' switch or ~cast(int)(foo)
/tmp/test.d(5): Deprecation: integral promotion not done for -foo, use '-transition=intpromote' switch or -cast(int)(foo)
/tmp/test.d(6): Deprecation: integral promotion not done for -foo, use '-transition=intpromote' switch or -cast(int)(foo)


To me it seems that line 5 should result in error since I am trying to coerce an int into a byte.

void main() {                      // 1
  byte foo;			   // 2
  foo = ~foo;			   // 3
  foo = ~cast(int) (foo);	   // 4 -- this should be an error but no
  foo = -foo;			   // 5
  foo = cast(byte) (-foo);	   // 6
}