Re: [boost] boost::implicit_cast - no documentation, misleading header comment

From: David Abrahams (dave_at_[hidden])
Date: 2005-06-17 09:42:18

Phil Richards <news_at_[hidden]> writes:

> In a moment of outstanding boredom, I ran the regression tests for
> the latest gcc 4.0.1 snapshot under Linux.  Looking through the
> fails in the HTML report I noticed that boost::implicit_cast was
> shown as failing test implicit_cast_fail.
>
> The output of the test is:
>
> ../libs/conversion/test/implicit_cast_fail.cpp: In function 'int test_main(int, char**)':
> ../libs/conversion/test/implicit_cast_fail.cpp:21: error: conversion from 'const char*' to non-scalar type 'foo' requested
> ../libs/conversion/test/implicit_cast_fail.cpp:21: warning: unused variable 'x'
> ../libs/conversion/test/implicit_cast_fail.cpp:22: warning: control reaches end of non-void function
> (failed-as-expected) ../bin/boost/libs/conversion/test/implicit_cast_fail.test/gcc/debug/implicit_cast_fail.o

That looks like it's passing the test!

> Given that (as far as my understanding of the test suite goes)
> compilation failure is the expected behaviour, why is this highlighted
> as a test failure in the HTML report?
>
> Anyway, off I trundle to find out what it is supposed to do.
> Unfortunately, there doesn't appear to be any documentation for
> "implicit_cast".  So I look in the header file and find:
>
>     // implementation originally suggested by C. Green in
>     // http://lists.boost.org/MailArchives/boost/msg00886.php
>
> And dutifully follow the link to find an article by Peter Dimov
> about "Perfect Forwarding".

Oh, crud, I guess the links changed.

> I apologise if I'm being dumb and missing something obvious,
> but something looks a little screwy...

http://lists.boost.org/MailArchives/boost/msg56143.php explains part
of it.  The rest of the history is in the thread at
http://lists.boost.org/boost/2005/03/22849.php.  Follow the replies.

Patches welcome, as always!

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com