You can apply const to the whole of a static array type or to the element type thereof. Since static arrays have value semantics, the result is the same: you can neither change an element in the array nor reassign to it a whole new array. Nonetheless, DMD treats them as different types:
----- const_static_array_1.d -----
const(char)[26] abc1 = "abcdefghijklmnopqrstuvwxyz";
const(char[26]) abc2 = "abcdefghijklmnopqrstuvwxyz";
pragma(msg, typeof(abc1).stringof);
pragma(msg, typeof(abc2).stringof);
pragma(msg, (const(char)[26]).stringof);
pragma(msg, (const(char[26])).stringof);
pragma(msg, is(typeof(abc1) : typeof(abc2)).stringof);
pragma(msg, is(typeof(abc2) : typeof(abc1)).stringof);
pragma(msg, is(typeof(abc1) == typeof(abc2)).stringof);
----------
C:\Users\Stewart\Documents\Programming\D\d2\tests>dmd -c const_static_array_1.d
const(char)[26u]
const(char[26u])
const(char)[26u]
const(char[26u])
true
true
false
----------
Moreover, while they are implicitly convertible, that they are treated as different types creates a silly template incompatibility:
----- const_static_array_2.d -----
const(char)[26] abc1 = "abcdefghijklmnopqrstuvwxyz";
const(char[26]) abc2 = "abcdefghijklmnopqrstuvwxyz";
class Temp(T) {}
void main() {
Temp!(const(char)[26]) t1;
Temp!(const(char[26])) t2;
t1 = t2;
t2 = t1;
}
----------
C:\Users\Stewart\Documents\Programming\D\d2\tests>dmd const_static_array_2.d
const_static_array_2.d(10): Error: cannot implicitly convert expression (t2) of type const_static_array_2.Temp!(const(char[26u])).Temp to const_static_array_2.Temp!(const(char)[26u]).Temp
const_static_array_2.d(11): Error: cannot implicitly convert expression (t1) of type const_static_array_2.Temp!(const(char)[26u]).Temp to const_static_array_2.Temp!(const(char[26u])).Temp
----------
Comment #1 by smjg — 2009-01-10T10:48:12Z
The type should be reported as const(char[26]) in either case. And here's another case of the same basic bug:
----------
invariant(const(char)[26]) abc1 = "abcdefghijklmnopqrstuvwxyz";
const(invariant(char)[26]) abc2 = "abcdefghijklmnopqrstuvwxyz";
pragma(msg, typeof(abc1).stringof);
pragma(msg, typeof(abc2).stringof);
pragma(msg, (invariant(const(char)[26])).stringof);
pragma(msg, (const(invariant(char)[26])).stringof);
pragma(msg, is(typeof(abc1) : typeof(abc2)).stringof);
pragma(msg, is(typeof(abc2) : typeof(abc1)).stringof);
pragma(msg, is(typeof(abc1) == typeof(abc2)).stringof);
----------
C:\Users\Stewart\Documents\Programming\D\d2\tests>dmd -c const_static_array_3.d
immutable(char[26u])
const(immutable(char)[26u])
immutable(char[26u])
const(immutable(char)[26u])
true
true
false
----------
Again, the two should denote the exact same type, invariant(char[26u]). (immutable? invariant? See also issue 2572.)
Comment #2 by smjg — 2010-06-24T17:49:56Z
Created attachment 675
Example of a squashed summary line
Rendered by Firefox 3.6.3 at inner width 1000. If you make it much narrower, you get a horizontal scrollbar.
Comment #3 by smjg — 2010-06-24T17:52:10Z
Comment on attachment 675
Example of a squashed summary line
Sorry, attached to wrong bug report. Reposted on issue 4386.
Comment #4 by bugzilla — 2010-11-07T14:29:20Z
You're right, this is a bit of a mess and should be fixed.
