[cfe-dev] -static-libstdc++ & libc++abi

Thu Nov 17 20:35:46 PST 2016

Eric,

I initially started from configuration using "-DLIBCXX_ENABLE_SHARED=OFF
-DLIBCXX_ENABLE_STATIC_ABI_LIBRARY=ON". Clang built with this configuration
can not produce binaries at all (see below). Clang with just
"-DLIBCXX_ENABLE_STATIC_ABI_LIBRARY=ON"
fails the same way when I use "-static-libstdc++"

clang++ -std=c++11 -stdlib=libc++  -v test.cc
clang version 4.0.0 (http://llvm.org/git/clang.git
832a07c9d566c5aad19e1ba5c3c924d8d384499f)
(http://llvm.org/git/llvm.git fde9b8bfc220c589f9103b3919d1
07cd3e944cc6)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.4.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.0.0
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.4.0
Candidate multilib: .;@m64
Selected multilib: .;@m64
 "/usr/local/bin/clang-4.0" -cc1 -triple x86_64-unknown-linux-gnu
-emit-obj -mrelax-all -disable-free -disable-llvm-verifier
-discard-value-names -main
-file-name test.cc -mrelocation-model static -mthread-model posix
-mdisable-fp-elim -fmath-errno -masm-verbose -mconstructor-aliases
-munwind-tables -f
use-init-array -target-cpu x86-64 -v -dwarf-column-info
-debugger-tuning=gdb -resource-dir /usr/local/bin/../lib/clang/4.0.0
-internal-isystem /usr/loc
al/bin/../include/c++/v1 -internal-isystem /usr/local/include
-internal-isystem /usr/local/bin/../lib/clang/4.0.0/include
-internal-externc-isystem /us
r/include/x86_64-linux-gnu -internal-externc-isystem /include
-internal-externc-isystem /usr/include -std=c++11 -fdeprecated-macro
-fdebug-compilation-
dir / -ferror-limit 19 -fmessage-length 151 -fobjc-runtime=gcc
-fcxx-exceptions -fexceptions -fdiagnostics-show-option -o
/tmp/test-fa0ac9.o -x c++ tes
t.cc
clang -cc1 version 4.0.0 based upon LLVM 4.0.0svn default target
x86_64-unknown-linux-gnu
ignoring nonexistent directory "/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/bin/../include/c++/v1
 /usr/local/include
 /usr/local/bin/../lib/clang/4.0.0/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
test.cc:10:5: warning: expression result unused [-Wunused-value]
    dynamic_cast<B*>(v); // well-defined: v of type V*, V base of B,
results in B*
    ^~~~~~~~~~~~~~~~~~~
test.cc:11:5: warning: expression result unused [-Wunused-value]
    dynamic_cast<B*>(a); // undefined behavior: a has type A*, A not a base of B
    ^~~~~~~~~~~~~~~~~~~
2 warnings generated.

 "/usr/bin/ld" -z relro --hash-style=gnu --eh-frame-hdr -m elf_x86_64
-dynamic-linker /lib64/ld-linux-x86-64.so.2 -o a.out
/usr/lib/gcc/x86_64-linux-gn
u/5.4.0/../../../x86_64-linux-gnu/crt1.o
/usr/lib/gcc/x86_64-linux-gnu/5.4.0/../../../x86_64-linux-gnu/crti.o
/usr/lib/gcc/x86_64-linux-gnu/5.4.0/crtbe
gin.o -L/usr/lib/gcc/x86_64-linux-gnu/5.4.0
-L/usr/lib/gcc/x86_64-linux-gnu/5.4.0/../../../x86_64-linux-gnu
-L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/
usr/lib/x86_64-linux-gnu
-L/usr/lib/gcc/x86_64-linux-gnu/5.4.0/../../.. -L/usr/local/bin/../lib
-L/lib -L/usr/lib /tmp/test-fa0ac9.o -lc++ -lm -lgcc_s
-lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/5.4.0/crtend.o
/usr/lib/gcc/x86_64-linux-gnu/5.4.0/../../../x86_64-linux-gnu/crtn.o
/usr/local/bin/../lib/libc++.a(ios.cpp.o): In function
`std::__1::iostream_category()':
ios.cpp:(.text._ZNSt3__117iostream_categoryEv+0x24): undefined
reference to `__cxa_guard_acquire'
ios.cpp:(.text._ZNSt3__117iostream_categoryEv+0x34): undefined
reference to `__cxa_guard_release'
/usr/local/bin/../lib/libc++.a(ios.cpp.o): In function
`std::__1::ios_base::clear(unsigned int)':
ios.cpp:(.text._ZNSt3__18ios_base5clearEj+0x48): undefined reference
to `__cxa_allocate_exception'
ios.cpp:(.text._ZNSt3__18ios_base5clearEj+0x84): undefined reference
to `__cxa_throw'
ios.cpp:(.text._ZNSt3__18ios_base5clearEj+0x94): undefined reference
to `__cxa_free_exception'

On Thu, Nov 17, 2016 at 8:00 PM Eric Fiselier <eric at efcs.ca> wrote:

> On Thu, Nov 17, 2016 at 5:20 PM, Mike Aizatsky via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
> Hello!
>
> I've recently encountered a bug (
> https://llvm.org/bugs/show_bug.cgi?id=30919) and I would like an advice
> on how to approach it.
>
> It seems that right now libc++abi is not handled by Tools.cpp. Normal
> linking works  because:
>
> $ cat ~/out/llvm/default/lib/libc++.so
> INPUT(libc++.so.1 -lc++abi)
>
> And if I use -static-libstdc++ then c++abi is not automatically linked in
> at all.
>
> Is there a similar magic for .a files like for .so? Should Tools.cpp know
> about lc++abi? Are there any alternatives?
>
>
> First, Tools.cpp shouldn't know about libc++abi/libsupc++/libcxxrt or w/e
> C++ ABI library your STL is using.
>
> There are two alternatives to your problem.  If you want to use a static
> libc++abi you can build libc++ with LIBCXX_ENABLE_STATIC_ABI_LIBRARY=ON
> <http://libcxx.llvm.org/docs/BuildingLibcxx.html#cmdoption-arg-LIBCXX_ENABLE_STATIC_ABI_LIBRARY>
> .
> Alternatively you can define libc++.a as a linker script just like
> libc++.so. (Ex INPUT(libc++static.a -lc++abi))
>
> /Eric
>
>
>
>
> --
> Mike
> Sent from phone
>
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>
>
> --
Mike
Sent from phone
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