> SFS fails to compile with gcc 3.0, and it was tracked down to this > example code that reproduces the error:
This is not a bug in the compiler, but in your code. > a << 10; Here, a temporary of class aiosout must be initialized with an expression of type aios. This is defined in section 8.5.3, [dcl.init.ref]/3, where "cv1 T1" is "const aiosout" and "cv2 T2" is "aios". Therefore, the two types are not reference compatible, and the last section applies: # Otherwise, a temporary of type cv1 T1 is created and initialized # from the initializer expression using the rules for a non-reference # copy initialization (8.5). The reference is then bound to the # temporary. So the temporary is initialized using copy initialization; the code is rewritten as if const aiousout tmp = a; tmp << 10; Since aiousout is a class type, this involves calling a copy constructor, as if const aiousout tmp(aiousout(a)); Now, 12.8, [class.copy]/15, allows to elide the copy constructor, which g++ always did. 12.2, [class.temporary]/1, requires to still perform access checks for the copy constructor, even if it is not called: # Even when the creation of the temporary object is avoided (12.8), # all the semantic restrictions must be respected as if the temporary # object was created. Earlier g++ versions did not properly perform the access check for the copy constructor that was not called; this bug has been corrected in gcc 3. To make your code work, I recommend to rewrite it as aiosout tmp(a); tmp << 10; i.e. using direct initialization explicitly for a local variable. Regards, Martin
