[llvm-dev] Clang 3.8 and gcc 5.2 has difference in symbol names

[Yaron Keren via llvm-dev]

Please see https://llvm.org/bugs/show_bug.cgi?id=23529


2016-05-04 15:52 GMT+03:00 Nishidha Panpaliya via llvm-dev <
llvm-dev at lists.llvm.org>:

> Hi All,
>
> I've built LLVM 3.8 on POWER with gcc 5.2.1 version for one of our
> application. This application is built using -std=c++14 support.
> Using this particular combination, I'm getting one error where one of the
> exported symbols from our application (for a function returning std::string
> which is built by gcc) is different than the one when compiled by clang 3.8.
>
> I also tried to replicate this issue by using a small test application
> which has a function named GetString() returning std::string. When I
> compile this file using gcc 5.2, I see symbol name as
> "_Z9GetStringB5cxx11v" and when I compile the same file using clang++, I
> get symbol name as "_Z9GetStringv".
>
> In order to resolve this difference, I tried below things -
>
>    - gcc 5.2 with c++11 support has added this special behavior due to
>    which symbol name contains B5cxx11. Hence, I tried building LLVM/clang with
>    -std=c++14 support. But no luck.
>    - Even if I provide -std=c++14 while compiling this source file using
>    clang++, the result remained same.
>    - I tried setting -D_GLIBCXX_USE_CXX11_ABI=0 flag while compiling my
>    application using gcc. This approach atleast gave me some success. Symbols
>    generated for my source file after using flag were same as that of clang++
>    (i.e. without B5cxx11). But later my application failed at linking step for
>    some undefined references - some of the references were of the application
>    itself and a few from dependent libraries. I wanted to know if I would also
>    need to build my dependent libraries using this flag.
>
>
> I need some guidance here as to how I can build LLVM/clang so that it also
> generates symbols same as that of gcc5.2. I can't use any other version of
> gcc as I'll need rebuild lot of other dependencies.
>
> Kindly help me.
>
> Thanks,
> Nishidha
>
>
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