[Boost-bugs] [Boost C++ Libraries] #11582: Regression with -Woverloaded-virtual in unit_test_log_t

Subject: [Boost-bugs] [Boost C++ Libraries] #11582: Regression with -Woverloaded-virtual in unit_test_log_t
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-08-26 20:52:45

#11582: Regression with -Woverloaded-virtual in unit_test_log_t
-----------------------------------------------+---------------------
 Reporter:  Ben Wiederhake <Ben.Wiederhake@…>  |      Owner:  rogeeff
     Type:  Bugs                               |     Status:  new
Milestone:  To Be Determined                   |  Component:  test
  Version:  Boost Development Trunk            |   Severity:  Problem
 Keywords:                                     |
-----------------------------------------------+---------------------
 While trying to compile my code with "-Woverloaded-virtual -Werror", I
 found a shortcoming, possibly even a bug.

 In 1.59.0 (and, as far as I can see in git, all following versions),
 there are the following declarations/definitions:

 {{{
 class test_observer /* boost/test/tree/observer.hpp:40 */
 virtual void test_unit_skipped( test_unit const& tu, const_string)
    { test_unit_skipped( tu ); }
 virtual void test_unit_skipped( test_unit const& )
    {} ///< backward compartibility

 class unit_test_log_t /* boost/test/unit_test_log.hpp:97 */
 virtual void test_unit_skipped( test_unit const&, const_string );
 /* Actually uses the message in the implementation */
 /* Does not override Test_unit_skipped( test_unit const& ) */
 }}}

 The problem with this code is that code like the following simply will
 not work:

 {{{
 unit_test_log_t& foobar;
 test_unit const& tu;
 foobar.test_unit_skipped( tu ); // <-- Error!
 }}}

 g++ would say "candidate expects 2 arguments, 1 provided". clang++ is a
 tad more helpful, and would say: "too few arguments to function call,
 expected 2, have 1; did you mean 'test_observer::test_unit_skipped'?"
 In case you're unfamiliar with that behaviour, see this specific answer:
 http://stackoverflow.com/a/6035884/3070326

 (Error messages are from a different compilation, but should be the same.)

 I hope I have now established that -Woverloaded-virtual "has a point".

 I don't fully understand why unit_test_log_t doesn't override the
 other signature, too; but it should be easily possible to override
 it with something like:

 {{{
 test_unit_skipped( tu, "<No message>" );
 }}}

 However, I do not yet fully understand the context of unit_test_log_t,
 so maybe such a call cannot occur. That's why I'm unable to make a
 patch from that idea.

 At the very least, this issue is annoying for people who use Boost.Test
 and try to compile with -Woverloaded-virtual.

 Note that Boost.Test 1.58.0 did *not* exhibit this issue, so I felt free
 to put "regression" in the subject and 'severity'.

 (PS: Thanks to Rene Rivera for redirecting me away from the mailing list,
 and  Raffi Enficiaud for redirecting me to this trac.)

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11582>
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