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Issue 2953 - tuple.length rejected as a tuple parameter in a static foreach
Summary: tuple.length rejected as a tuple parameter in a static foreach
Status: RESOLVED FIXED
Alias: None
Product: D
Classification: Unclassified
Component: dmd (show other issues)
Version: D1 (retired)
Hardware: x86 Windows
: P2 normal
Assignee: No Owner
URL:
Keywords: patch, rejects-valid
Depends on:
Blocks:
 
Reported: 2009-05-08 03:41 UTC by Don
Modified: 2014-04-18 09:12 UTC (History)
2 users (show)

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Description Don 2009-05-08 03:41:22 UTC 
This bug was created from Bug 2687.
Workaround (D2), change the foreach to enum args_length = args.length; foreach( x ; Range!(args_length) ){ }

---

template Tuple(T...){
    alias T Tuple;
}
template Range(int b){
        alias Tuple!(1) Range;
}
void foo()(){
     Tuple!(int, int) args;
     foreach( x ; Range!(args.length) ){ }
}

void main(){
    foo!()();
}
---
ice.d(411): Error: identifier 'length' of 'args.length' is not defined
ice.d(411): Error: template instance Range!(int) does not match template declara
tion Range(int b)
ice.d(411): Error: foreach: void is not an aggregate type
ice.d(416): Error: template instance ice.foo!() error instantiating
Comment 1 Ellery Newcomer 2011-08-11 18:51:10 UTC 
Ran into something similar a while back, but I don't think foreach has anything to do with it:

template Sequenced(){
    template Inner(ThisNode, Value, size_t N){
    }
}

struct IndexedBy(L...)
{
    alias L List;
}

class MIC(IndexedBy){
    alias int ThisNode;

    void _RemoveAllBut(size_t N)(ThisNode* node){
    }

    /// disattach node from all indeces.
    alias _RemoveAllBut!(IndexedBy.List.length) _RemoveAll;
}

void main(){
    alias MIC!(IndexedBy!(Sequenced!())) C;
}



yields 1 error message:

Error: identifier 'length' of 'IndexedBy.List.length' is not defined
Comment 2 Don 2011-08-11 22:40:45 UTC 
Reduced form of the test case in comment 1:
---------
template Sequenced() {}

struct IndexedBy(L...) {
    alias L List;
}

struct MIC(F){
    int[F.List.length] w;
}

alias MIC!( IndexedBy!(Sequenced!()) ) C;
----------
test3.d(14): Error: identifier 'length' of 'F.List.length' is not defined
test3.d(17): Error: template instance test3.MIC!(IndexedBy!(__T9SequencedZ)) err
or instantiating

Looks like a failure to resolve aliases, for a template which is a member of a tuple.