Dependency through template use

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2 total messages Started by Marc Girod Thu, 23 Nov 1995 15:32

#2700

Author: Marc Girod
Date: Thu, 23 Nov 1995 15:32

39 lines
2028 bytes

Hello!

I compile the following example:
--------------------------------
template <class T> class X {
    T t_;
};

class Y;

class Z {
    X<Y>* x_;
};
--------------------------------

and get an error from my compiler:

CC: "foo.C", line 2: error:  Y undefined, size not known (1437)
"foo.C", line 2: 	 error detected during the instantiation of X <Y> 
"foo.C", line 8: 	 is the site of the instantiation

Could you confirm that my compiler is wrong, and should not require
that I #include the definition of type Y.

I could not find the answer in the draft (I looked in chapter
14.2...).

Thanks!
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Re: Dependency through template use

#2719

Author: David Vandevoorde
Date: Fri, 24 Nov 1995 17:24

26 lines
1277 bytes

>>>>> "MG" == Marc Girod <girod@dshp01.trs.ntc.nokia.com> writes:
[...]
MG> template <class T> class X {
MG>     T t_;
MG> };

MG> class Y;

MG> class Z {
MG>     X<Y>* x_;
MG> };
[...]

I'm pretty sure it's correct C++ under the current DWP
(and my compiler compiles it quietly). If it is a serious
problem, does a typedef help?
	class Z {
	    typedef X<Y>* Ptr_;
	    Ptr_ x_;
	};

	Daveed

[ comp.std.c++ is moderated.  Submission address: std-c++@ncar.ucar.edu.
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