Re: [boost] [filesystem] issue with path::iterator

From: Beman Dawes (bdawes_at_[hidden])
Date: 2004-08-22 14:13:54

At 12:56 PM 8/11/2004, Martin Wille wrote:
 >Hello,
 >
 >a momemnt ago, someone reported a problem on IRC regarding
 >boost::filesystem::path::iterator. He basically has code like
 >this:
 >
 >using boost::filesystem::path;
 >path::iterator i = somepath.begin();
 >path::iterator j = i++;
 >
 >That code used to work but stopped working recently.
 >Now, there is a compiler error saying that the value
 >returned by i++ is not suitable for constructing j:
 >
 >error: conversion from `
 >boost::detail::postfix_increment_proxy<boost::filesystem::path::iterator>'
 >    to non-scalar type `boost::filesystem::path::iterator' requested
 >
 >
 >I suspect the change was caused by a recent change to iterator adaptors.
 >
 >
 >Investigation of the problem revealed that the documenation for
 >path::iterator says it is a bidirectional iterator while the
 >implementation uses single_pass_traversal_tag. This looks
 >wrong to me.

I agree with your analysis.

What is weird is that even though the single_pass_traversal_tag is given, 
the path_test.cpp regression test uses operator-- in tests, and they 
compile fine.

So it looks like there is also a bug in iterator adaptors too, since I 
would think that the use of operator-- on a single pass iterator should 
fail.

Thanks,

--Beman