[cfe-dev] Linking ProfileRT when using -nodefaultlibs

[Dan Albert]

Didn't realized we even supported using GCC to build libc++.

On Mon, Nov 10, 2014 at 11:45 AM, Eric Fiselier <eric at efcs.ca> wrote:

> > Has anyone actually run the tests against GCC recently? IIRC it
> requires some local modifications anyway.
>
> I do it occasionally. Most parts work out of the box. I haven't tried
> using sanitizers with GCC though.
> Don't forget the CMake build also uses -nodefaultlibs so it's not just the
> test suite that would require special handling of GCC.
>
> /Eric
>
> On Mon, Nov 10, 2014 at 12:43 PM, Dan Albert <danalbert at google.com> wrote:
>
>> Yes, that is the downside.
>>
>> Has anyone actually run the tests against GCC recently? IIRC it requires
>> some local modifications anyway.
>>
>> On Mon, Nov 10, 2014 at 11:40 AM, Eric Fiselier <eric at efcs.ca> wrote:
>>
>>> > The reason we use -nodefaultlibs is to avoid linking the system's
>>> libc++. There's a -nostdinc++, maybe there should be a -nostdlib++? Or
>>> perhaps -stdlib=none?
>>> -nostdlib already exists but it acts like -nodefaultlibs and it drops
>>> the startup files as well.
>>> I would support -stdlib=none but I'm hesitant to start depending on
>>> Clang only flags. It would be nice to not have to special case GCC.
>>>
>>> /Eric
>>>
>>> On Mon, Nov 10, 2014 at 12:37 PM, Dan Albert <danalbert at google.com>
>>> wrote:
>>>
>>>> The reason we use -nodefaultlibs is to avoid linking the system's
>>>> libc++. There's a -nostdinc++, maybe there should be a -nostdlib++? Or
>>>> perhaps -stdlib=none?
>>>>
>>>> That would let us stop preventing the driver from doing its job...
>>>>
>>>> On Mon, Nov 10, 2014 at 11:26 AM, Eric Fiselier <eric at efcs.ca> wrote:
>>>>
>>>>> Thanks for the heads up about the dead link. I've attached the output
>>>>> to this email.
>>>>>
>>>>> I spent some time last night trying to fix this problem in Clang but I
>>>>> had no luck :(
>>>>> Moving the compiler-rt library before the linker inputs only created
>>>>> more issues.
>>>>>
>>>>> /Eric
>>>>>
>>>>> On Mon, Nov 10, 2014 at 11:40 AM, Justin Bogner <mail at justinbogner.com
>>>>> > wrote:
>>>>>
>>>>>> Eric Fiselier <eric at efcs.ca> writes:
>>>>>> > Hello,
>>>>>> >
>>>>>> > I'm working on making libc++ generate code coverage data. This
>>>>>> means that
>>>>>> > libclang_rt.profile.x86_64.a is put into the link command before
>>>>>> '-lc' and
>>>>>> > other dependencies.
>>>>>> > I suspect this change in library order causes the linker errors I
>>>>>> see while
>>>>>> > running the tests.
>>>>>> >
>>>>>> > I have a couple of questions:
>>>>>> >  - Should -ftest-coverage be passed when linking libc++?
>>>>>> >  - Is there a way to link libclang_rt.profile.x86_64.a after the
>>>>>> given linker
>>>>>> >    flags
>>>>>> >
>>>>>> > This file shows the ld invocation with and without -nodefaultlibs
>>>>>> as well as
>>>>>> > the error produced when
>>>>>> > linking tests w/ -nodefaultlibs
>>>>>> > http://pastebin.com/QWagJpsW
>>>>>>
>>>>>> There's nothing there? Mailing this text directly seems simpler than a
>>>>>> pastebin to me.
>>>>>>
>>>>>> This issue and a few other things I've seen recently make me think
>>>>>> that
>>>>>> compiler-rt and -nodefaultlibs don't interact very well in general. I
>>>>>> guess there's work to be done in the area.
>>>>>>
>>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> cfe-dev mailing list
>>>>> cfe-dev at cs.uiuc.edu
>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>>>>>
>>>>>
>>>>
>>>
>>
>
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