[cfe-dev] Linking ProfileRT when using -nodefaultlibs

[Eric Fiselier]

> 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.
>>>
>>>
>>
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>>
>>
>
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