[clang] Patch for 6037

[Nathan Sidwell]

ping?

On 12/24/14 11:46, Nathan Sidwell wrote:
> On 12/16/14 23:26, Richard Smith wrote:
>> On Fri, Dec 12, 2014 at 6:53 AM, Nathan Sidwell <nathan at acm.org
>> <mailto:nathan at acm.org>> wrote:
>
> This patch addresses bug 6037 http://llvm.org/bugs/show_bug.cgi?id=6037
> A request for a class definition to warn about inaccessible direct base classes.
>
>> That said, you should be able to do this even more efficiently by collecting a
>> list of all indirect base classes then checking if any direct base class is on
>> the list. (If any is, you'll still need the code you already have, in order to
>> describe the ambiguity.)
>
> Patch adjusted.  Builds a std::set of indirect bases of the new class -- if it
> has more than 1 direct base.  Then checks if a direct base is in the set before
> determining the ambiguity of that base.[*]   Note that a direct and indirect
> base duplicate could exist, but not be ambiguous iff they are both virtual.
> Rather than track that data in the std::set, we just check the result of
> determining the base path ambiguity in the later loop.
>
>
>> def warn_inaccessible_base_class : Warning<
>>    "direct base %0 is inaccessible due to ambiguity:%1">,
>>    InGroup<DiagGroup<"warning-flag">>;
>
> Done.  Added -W[no-]inaccessible-base
>
> A bunch of existing tests trigger.  For some of them I added
> -Wno-inaccessible-base to the test flags, for some I added the expected warning
> check -- depending on whether I judged the warning appropriate for the test
> case, or merely coincidental.  A new test
> tools/clang/test/SemaCXX/accessible-base.cpp is added
>
> built and tested on x86-linux.
>
> ok?
>
> nathan
>
> [*] As an aside, I wonder if completing the std:set with the direct bases and
> keeping it with the RecordDecl would speed up base conversion checks -- the base
> conversion machinery could use it for a quick 'is this even worth figuring out'
> check.