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From: tuck@jason.cs.unc.edu (Russ Tuck)
Newsgroups: comp.lang.c++
Subject: Re: user-defined conversion--bug or error?
Keywords: user-defined conversion, cfront 2.0, g++ 1.36.1
Message-ID: <10993@thorin.cs.unc.edu>
Date: 6 Dec 89 18:33:36 GMT
References: <10986@thorin.cs.unc.edu>
Sender: news@thorin.cs.unc.edu
Reply-To: tuck@jason.cs.unc.edu (Russ Tuck)
Organization: University Of North Carolina, Chapel Hill
Lines: 74

Simplifying my earlier program slightly gave interesting results.
First, I removed all the "const" keywords, to make it legal C++ 1.2.
With this change, AT&T cfront 1.2 compiled it without error (but 2.0
gave the same error).

Then I deleted the "&" chars, so + and conversions use valuess instead
of references.  This finally compiled without error with cfront 2.0
(as well as 1.2 and g++).

This suggests that the problem is in cfront 2.0.  Any comments?
Suggestions??

Here are the details...
CC.new = AT&T cfront 2.0
CC     = AT&T cfront 1.2
g++    = GNU g++ 1.36.1
piglet = Sun-3/60, SunOS 4.0.3

(no const, keep ref &)
tuck@piglet> cat type2ac.C
class A {
 public:
  friend A operator+ (A& lsrc, A& rsrc);
};

class B {
 public:
  B();
  operator A&();
};

main()
{
  A a0;
  B b0, b1;

  a0 = b0 + b1;    // legal???
}

tuck@piglet> CC.new -c type2ac.C
CC  type2ac.C:
"type2ac.C", line 17: error: ambiguous use of overloaded +:  B  and  B 
1 error
tuck@piglet> CC -c type2ac.C
tuck@piglet> g++ -c type2ac.C
tuck@piglet> 

(no const, no ref &)
tuck@piglet> cat type2ad.C
class A {
 public:
  friend A operator+ (A lsrc, A rsrc);
};

class B {
 public:
  B();
  operator A();
};

main()
{
  A a0;
  B b0, b1;

  a0 = b0 + b1;    // legal???
}

tuck@piglet> CC.new -c type2ad.C
CC  type2ad.C:
cc  -c  type2ad.c
tuck@piglet> CC -c type2ad.C
tuck@piglet> g++ -c type2ad.C
tuck@piglet>