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<div>Hi everyone,</div>
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<div>I just reported the following issue: <a href="https://llvm.org/bugs/show_bug.cgi?id=24927">https://llvm.org/bugs/show_bug.cgi?id=24927</a></div>
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<pre class="bz_comment_text" id="comment_text_0" style="white-space: pre-wrap; width: 50em;"><font face="Calibri">Using the Xcode 7 linker, one gets messages such as the following when linking objects generated using llvm:
<b><i>ld: warning: object file (foo.o) was built for newer OS X version (14.5) than being linked (10.9)</i></b>
The issue is the following:
a) In lib/Support/Unix/Host.inc, sys::getDefaultTargetTriple() sets the OS name to darwin14.5 when running on MaxOS X 10.10. 14.5 is the Darwin kernel version as reported by uname.
b) In lib/CodeGen/AsmPrinter.cpp, AsmPrinter::doInitialization() writes out this version number to the LC_VERSION_MIN_MACOSX of the generated object.
c) The XCode 7 linker seems to expect that LC_VERSION_MIN_MACOSX contains the minimum version number of the MacOS X SDK (10.9, 10.11, ...), NOT the Darwin kernel version number!
<i><b>AFAICT, LLVM had this wrong behaviour for a long time. The only new thing with Xcode 7 is that the linker is now reporting a warning for the version mismatch.</b></i></font></pre>
<pre class="bz_comment_text" id="comment_text_0" style="white-space: pre-wrap; width: 50em;"><font face="Calibri">As a workaround, we are temporarily stripping out the darwin kernel version number from the triple in our project code. Something like:</font></pre>
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<pre class="bz_comment_text" id="comment_text_1" style="white-space: pre-wrap; width: 50em;"><font face="Consolas" style="font-size: 12px;">// FIXME: LLVM confuses Darwin Kernel version numbers with MacOS X SDK
// version. By stripping out the kernel version number, we prevent the
// LC_VERSION_MIN_MACOSX directive from being emitted. Hopefully, that
// will get fixed by LLVM 3.8...
//
// See LLVM bug 24927: https://llvm.org/bugs/show_bug.cgi?id=24927</font><font face="Consolas"><span style="font-size: 12px;">#if defined(OSX)
#if (LLVM_VERSION_MAJOR < 3) || ((LLVM_VERSION_MAJOR == 3) && (LLVM_VERSION_MINOR < 8 ))
triple = Triple(triple.getArchName(),
triple.getVendorName(),
"darwin",
triple.getEnvironmentName());
#endif
#endif</span></font></pre>
<pre class="bz_comment_text" id="comment_text_1" style="white-space: pre-wrap; width: 50em;"><span style="font-family: Calibri;">This prevents the LC_VERSION_MIN_MACOSX directives from being emitted into the LLVM generated object files.</span></pre>
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<pre class="bz_comment_text" id="comment_text_1" style="font-size: medium; font-family: Calibri, sans-serif; white-space: pre-wrap; width: 50em;"><div><b><i>Any suggestions how to go about fixing LLVM to generate the correct <span style="font-family: Calibri;"> LC_VERSION_MIN_MACOSX minimum SDK version number ? There seems to be no way to pass this information correctly through the Triple!</span></i></b></div><div><font face="Calibri"><br></font></div><div><font face="Calibri">Thanks,</font></div><div><font face="Calibri">Benoit</font></div></pre>
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