[PATCH] D21607: [ELF] - Proccess 'extern' keyword in version scripts.

[Ed Maste via llvm-commits]

On 22 June 2016 at 09:27, George Rimar <grimar at accesssoftek.com> wrote:
> grimar created this revision.
> grimar added reviewers: rafael, ruiu.
> grimar added subscribers: llvm-commits, grimar.
> Herald added a subscriber: emaste.
>
> During investigation about FreeBsd scripts I found that few of them uses
> 'extern' keyword. This patch just reads all globals inside as regular ones.
>
> Note: I downloaded FreeBsd sources and tried to link with every *.map file in batch mode,
> some of them are not script files, so I had to skip them manually.
> Seems that this one in combination with D21556 allows to parse all available
> FreeBsd version scripts.

I spoke too soon in my earlier reply to this thread. We do have
version scripts in FreeBSD for Tier-1 architectures that use extern
C++ in the version definitions: libcxxrt is intended to be a libsupc++
drop-in replacement and has quite a few typeinfo, vtable and other C++
symbols in the Version.map.

As an aside it looks like the error handling reports the wrong line
for "extern." This snipped from the Version.map:

    43      __gxx_personality_v0;
    44
    45      extern "C++" {
    46          # Type info classes and their destructors
    47          "__cxxabiv1::__array_type_info";

produced this error:

line 43: extern keyword is not supported
    __gxx_personality_v0;
                        ^

As it turns out FreeBSD's GNU ld 2.17.50 isn't able to demangle a
number of symbols and so there are a set of explicit mangled symbols
in the Version.map:

   115          # C++11 typeinfo not understood by our linker
   116          # std::nullptr_t
   117          _ZTIDn;_ZTIPDn;_ZTIPKDn;
   118          # char16_t
   119          _ZTIDi;_ZTIPDi;_ZTIPKDi;
   120          # char32_t
   121          _ZTIDs;_ZTIPDs;_ZTIPKDs;
   122          # IEEE 754r decimal floating point
   123          _ZTIDd;_ZTIPDd;_ZTIPKDd;
   124          _ZTIDe;_ZTIPDe;_ZTIPKDe;
   125          _ZTIDf;_ZTIPDf;_ZTIPKDf;
   126          # IEEE 754r half-precision floating point
   127          _ZTIDh;_ZTIPDh;_ZTIPKDh;