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Bug 10871 – Typedef doesn't work with is null

Status: RESOLVED
Resolution: WONTFIX
Severity: normal
Priority: P2
Component: phobos
Product: D
Version: D2
Platform: All
OS: All
Creation time: 2013-08-22T15:05:22Z
Last change time: 2019-11-14T14:34:16Z
Assigned to: No Owner
Creator: John Colvin

Comments

Comment #0 by john.loughran.colvin — 2013-08-22T15:05:22Z

import std.typecons; alias Typedef!(void*) VP; void main() { VP vp; assert(vp is null); //won't compile } Error: incompatible types for ((vp) is (null)): 'Typedef!(void*, null)' and 'typeof(null)'

Comment #1 by andrej.mitrovich — 2013-08-22T15:09:02Z

I'm not sure how we could implement this, we don't have an "opIs" operator.

Comment #2 by john.loughran.colvin — 2013-08-22T15:17:08Z

(In reply to comment #1) > I'm not sure how we could implement this, we don't have an "opIs" operator. yeah I have no idea either. Is there any other way of getting something like a type-safe alias?

Comment #3 by bugzilla — 2019-11-14T14:34:16Z

I don't think that we can do here something. Instead of assert(vp is null) you could use assert(cast(TypedefType!VP) vp is null), but I don't know, if that is, what you are looking for.