[cfe-dev] Hello from a newcomer! + Bug 26834

Thu Mar 9 10:39:44 PST 2017

It isn't present because to reproduce the bug, we only copy the
included header files:

$ clang -Xclang -header-include-file -Xclang included_files.txt
-fsyntax-only T.cpp && sed -i '/<command line>/d' included_files.txt

$ cat included_files.txt | xargs -I$ cp --parents $ includes/

$ clang++ -fsyntax-only --sysroot="./includes/" T.cpp -v

What's the idea behind checking for crtbegin.o specifically?

On Thu, Mar 9, 2017 at 6:30 PM, Jonathan Roelofs <jonathan at codesourcery.com>
wrote:

>
>
> On 3/8/17 1:36 PM, kinan.sarmini at gmail.com wrote:
>
> It does find the toolchain in the directory given by the sysroot flag, and
> lists it as a candidate GCC Installation. The problem is it also checks for
> the existence of crtbegin.o in the corresponding lib directory (and
> considers the installation invalid when crtbegin.o is not present),
>
>
> Why isn't it present?
>
> which clearly isn't required when only doing syntax checking.
>
> As I see it, one way to fix this is to make the GCC installation detector
> aware of the compilation mode (or final phase), but I'm not sure whether
> this kind of dependency is good. Any ideas?
>
>
> Specializing this check so that it only looks for crtbegin.o when it
> absolutely needs it seems like a bad idea to me: you'll have very
> complicated logic to compute all the possible sets of driver options where
> it wouldn't be used.
>
>
> Jon
>
>
> On Tue, Mar 7, 2017 at 6:10 PM, Jonathan Roelofs <
> jonathan at codesourcery.com> wrote:
>
>>
>>
>> On 3/7/17 6:32 AM, Vassil Vassilev via cfe-dev wrote:
>>
>>> On 02/03/17 12:58, kinan.sarmini at gmail.com via cfe-dev wrote:
>>>
>>>> Hello everyone,
>>>>
>>>> a quick intro: I'm planning to participate in Google Summer of Code
>>>> this year as a student, and I'm really interested in the llvm project
>>>> in general and clang in particular. To increase my chances of getting
>>>> accepted and to get a better understanding of the project and its code
>>>> base, I'm currently working on fixing some open bugs.
>>>>
>>>> I started working on bug #26834 (as suggested by Vassil Vassilev), and
>>>> i have a couple of questions. I hope this is the right place to ask.
>>>> I'm still new to the project, so please bear with me as my questions
>>>> might be silly.
>>>> So regarding bug #26834: I've figured that the reason the right
>>>> headers aren't being added is because every candidate gcc installation
>>>> is scanned for Multilibs, and if they aren't detected, then the gcc
>>>> installation is ignored. Now I'm not sure which one is the right
>>>> behavior, i.e. is the check for Multilibs necessary
>>>> ( https://github.com/llvm-mirror/clang/blob/master/lib/Driver/
>>>> ToolChains.cpp#L2798
>>>> )?
>>>>
>>> Maybe you can ping the person who worked in that area (git blame should
>>> tell you).
>>>
>>> If you know how to fix the issue, fix it, run the test suite and if all
>>> is green submit a patch for review at: http://reviews.llvm.org/ adding
>>> as reviewers the people worked in that area.
>>>
>>
>> Feel free to add me as a reviewer.
>>
>> I suspect the bug is that clang calls the target triple:
>> "x86_64-unknown-linux-gnu" and gcc calls it: "x86_64-linux-gnu", and thus
>> doesn't find the toolchain there.
>>
>> Maybe for ".*-none-.*-.*" and ".*-unknown-.*-.*" triples we ought to
>> search the corresponding ".*-.*-.*" directories?
>>
>> The output from '-v' ought to tell you about which candidate gcc
>> installations/multilibs it found, if everything is working correctly.
>>
>>
>> Cheers,
>>
>> Jon Roelofs
>>
>>
>>
>>> -- Vassil
>>>
>>>>
>>>> Thanks!
>>>>
>>>> --
>>>> Regards,
>>>> Kinan.
>>>>
>>>>
>>>> _______________________________________________
>>>> cfe-dev mailing list
>>>> cfe-dev at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> cfe-dev mailing list
>>> cfe-dev at lists.llvm.org
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>>>
>>>
>> --
>> Jon Roelofs
>> jonathan at codesourcery.com
>> CodeSourcery / Mentor Embedded
>>
>
>
>
> --
> Regards,
> Kinan.
>
>
> --
> Jon Roelofsjonathan at codesourcery.com
> CodeSourcery / Mentor Embedded
>
>

-- 
Regards,
Kinan.
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