[cfe-dev] Latest clang from source breaks clang on Windows targeting gcc linking

[Yaron Keren]

See r244407 for a fuller patch with test case. It may also solve the other
issues.
If not, the best way to diagnose such problem is to run clang++ and g++
with -v argument and the same pther arguments of the case, comparing both
compiler outputs to see what's different.
With this input we could patch the mingw toolchain.


2015-08-08 22:37 GMT+03:00 Edward Diener <eldlistmailingz at tropicsoft.com>:

> On 8/8/2015 1:59 PM, Yaron Keren wrote:
>
>> I'm looking into this, see https://llvm.org/bugs/show_bug.cgi?id=24395
>> The solution is somewhat more compilcated but you can use the patch
>> there for now.
>>
>
> The patch solved the general problem I illustrated below. Thanks !
>
> But for the example in my other posts, where an exception was being thrown
> from a module using as a type a class that is in another DLL that is being
> exported/imported, the attempt to link to that DLL now fails with:
>
> ex_exception.obj: In function `ex_exception':
> ex_exception.cpp:42: undefined reference to `_Unwind_Resume'
> ex_xml_exception.obj: In function `ex_xml_exception':
> ex_xml_exception.cpp:32: undefined reference to `_Unwind_Resume'
> ex_xml_exception.cpp:39: undefined reference to `_Unwind_Resume'
> ex_xml_exception.cpp:42: undefined reference to `_Unwind_Resume'
> clang++.exe: error: linker command failed with exit code 1 (use -v to see
> invocation)
>
> These error messages are exactly the same whether or not I attempt to
> export/import the individual member functions of a visible class or whether
> I attempt to export/import the class as a whole. At least the previous
> error messages which occurred in the above situation have disappeared <g>.
>
> If you need for me to repeat the ex_exception, ex_xml_exception, and
> throw_exception_ex source, with their command lines, in this post I will be
> glad to do it.
>
> Searching the web for "undefined reference to `_Unwind_Resume'" yields
> various possibilities but none are definitive for this case AFAICS.
>
>
>> 2015-08-08 20:20 GMT+03:00 Edward Diener
>> <eldlistmailingz-5p0dqD/c5LGWd6l5hS35sQ at public.gmane.org
>> <mailto:eldlistmailingz-5p0dqD/c5LGWd6l5hS35sQ at public.gmane.org>>:
>>
>>
>>     Some change in the latest source has completely broken linking for
>>     clang on Windows targeting gcc.
>>
>>     // ex_aclass.hpp
>>
>>     #ifndef EX_ACLASS_HPP
>>     #define EX_ACLASS_HPP
>>     #if defined(BLD_EX_EXAMPLE)
>>              #define EX_DECL __attribute__((__dllexport__))
>>     #else
>>              #define EX_DECL __attribute__((__dllimport__))
>>     #endif
>>     class EX_DECL ex_aclass
>>     {
>>     public:
>>          int a_function(long);
>>     };
>>     #endif // EX_ACLASS_HPP
>>
>>     // ex_aclass.cpp
>>
>>     #define BLD_EX_EXAMPLE
>>     #include "ex_aclass.hpp"
>>     int ex_aclass::a_function(long amt)
>>              {
>>              return(amt > 1000000 ? 10 : 20);
>>              }
>>
>>     // Compile ex_aclass.cpp
>>
>>     clang++.exe -c -x c++ -D__MINGW_FORCE_SYS_INTRINS -O0 -g -fno-inline
>>     -Wall -g -march=i686 -m32 -o "ex_aclass.obj" "ex_aclass.cpp"
>>
>>     // Link into ex_ac.dll
>>
>>     clang++.exe" -o "ex_ac.dll" -Wl,-soname -Wl,ex_ac.dll -shared
>>     -Wl,--start-group "ex_aclass.obj" -Wl,-Bstatic -Wl,-Bdynamic
>>     -Wl,--end-group -g -march=i686 -m32
>>
>>
>> libmingw32.a(lib32_libmingw32_a-pseudo-reloc.o):pseudo-reloc.c:(.text+0x1d6):
>>     undefined reference to `__chkstk_ms'
>>     clang++.exe: error: linker command failed with exit code 1 (use -v
>>     to see invocation)
>>
>>     Nor does it matter what source file is used in general, whenever the
>>     link is done for anything the "undefined reference to `__chkstk_ms'"
>>     occurs.
>>
>>     Can some one of the clang developers please look at this ?
>>
>>     I am using clang on Windows with the 32-bit version of
>>     mingw-64/gcc-5.1 as i686-5.1.0-posix-dwarf-rt_v4-rev0.
>>
>>     I realize the current problems for clang on Windows targeting gcc
>>     may have occurred trying to fix a more specific problem I reported
>>     in two other threads about linkage failure using dllexport and
>>     dllimport attributes on Windows, but going from a situation where a
>>     specific problem broke the linking to all situations are broken when
>>     attempting to link is not good.
>>
>>     I tried looking at the clang unit tests and how they can be run on
>>     Windows but found very little information about both. I wouldn't
>>     mind contributing some basic unit tests, even though I am not a
>>     clang developer, just to make sure that clang on Windows targeting
>>     gcc will work when compiling/linking dlls and using those dlls from
>>     another module, if I could understand what to do. That way such a
>>     snafu as this latest breakage would not occur so easily as whatever
>>     broke in the change should have been caught by some unit tests.
>>     _______________________________________________
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>>
>>
>>
>>
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