digitalmars.D.bugs - [Issue 2571] New: const static arrays: const(T)[N] and const(T[N]) are the same, but DMD treats them as different
- d-bugmail puremagic.com (60/60) Jan 10 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2571
- d-bugmail puremagic.com (35/35) Jan 10 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2571
- d-bugmail puremagic.com (9/9) Jun 24 2010 http://d.puremagic.com/issues/show_bug.cgi?id=2571
- d-bugmail puremagic.com (12/12) Jun 24 2010 http://d.puremagic.com/issues/show_bug.cgi?id=2571
- d-bugmail puremagic.com (10/10) Nov 07 2010 http://d.puremagic.com/issues/show_bug.cgi?id=2571
- d-bugmail puremagic.com (11/11) Nov 07 2010 http://d.puremagic.com/issues/show_bug.cgi?id=2571
http://d.puremagic.com/issues/show_bug.cgi?id=2571
Summary: const static arrays: const(T)[N] and const(T[N]) are the
same, but DMD treats them as different
Product: D
Version: 2.023
Platform: PC
OS/Version: Windows
Status: NEW
Keywords: rejects-valid, wrong-code
Severity: normal
Priority: P2
Component: DMD
AssignedTo: bugzilla digitalmars.com
ReportedBy: smjg iname.com
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
----------
--
Jan 10 2009
d-bugmail puremagic.com
http://d.puremagic.com/issues/show_bug.cgi?id=2571
smjg iname.com changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|const static arrays: |const/invariant/immutable
|const(T)[N] and const(T[N]) |static arrays: const(T)[N]
|are the same, but DMD treats|and const(T[N]) are the
|them as different |same, but DMD treats them as
| |different
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.)
--
Jan 10 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2571 Created an attachment (id=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. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 24 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2571
Stewart Gordon <smjg iname.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
obsolete| |
(From update of attachment 675)
Sorry, attached to wrong bug report. Reposted on issue 4386.
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Jun 24 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2571
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bugzilla digitalmars.com
14:29:20 PST ---
You're right, this is a bit of a mess and should be fixed.
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Nov 07 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2571
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
20:42:55 PST ---
http://www.dsource.org/projects/dmd/changeset/744
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Nov 07 2010