<div dir="ltr">I bisected back to c4c3883b00d3a6aa657a5e3e515c90c9ea1f81c6 . Before that, our CMake scripts still required Python 2, which I no longer have installed (because it confuses lldb builds to have both Python 2 and 3 on the machine). Thus the dependency was probably introduced some time before April 2020.<div><br></div><div>So even if it was inadvertent, the problem has existed long enough that we probably just have to accept that libxml2 is now a requirement for LLVM builds on Windows. I'll propose a documentation change.</div><div><br></div><div>Adrian.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Aug 20, 2021 at 5:31 PM Shoaib Meenai <<a href="mailto:smeenai@fb.com">smeenai@fb.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal">This is a workaround and not a solution, but you should be able to add /manifest:no to your link flags (similar to
<a href="https://github.com/llvm/llvm-project/blob/3187a4f3f1d4d68a75a21154569db1232a62a57d/llvm/cmake/platforms/WinMsvc.cmake#L286-L287" target="_blank">
https://github.com/llvm/llvm-project/blob/3187a4f3f1d4d68a75a21154569db1232a62a57d/llvm/cmake/platforms/WinMsvc.cmake#L286-L287</a>) to prevent CMake from trying to invoke mt.<u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in"><b><span style="font-size:12pt;color:black">From:
</span></b><span style="font-size:12pt;color:black">cfe-dev <<a href="mailto:cfe-dev-bounces@lists.llvm.org" target="_blank">cfe-dev-bounces@lists.llvm.org</a>> on behalf of cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>><br>
<b>Reply-To: </b>Adrian McCarthy <<a href="mailto:amccarth@google.com" target="_blank">amccarth@google.com</a>><br>
<b>Date: </b>Friday, August 20, 2021 at 4:35 PM<br>
<b>To: </b>cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>><br>
<b>Subject: </b>[cfe-dev] Cannot CMake self-hosted clang on Windows for lack of libxml2<u></u><u></u></span></p>
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<p class="MsoNormal" style="margin-left:0.5in">I recently tried to build a self-hosted clang on Windows, but it fails when I use CMake to generate a Ninja file.<u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in">CMake finds my MSVC-built clang and tries to test it. This invokes llvm-mt (the LLVM implementation of the manifest tool). This tool depends on libxml2, which isn't typically installed on Windows.<u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in">I'm told the Windows build shouldn't need to invoke llvm-mt, so this is probably due to a CMake change. Unfortunately, I don't know how far back I have to go to find a working build so that I can bisect the breaking
change. It's been a long time since I've tried a self-hosted build.<u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in">Maybe somebody changed this intentionally, and we just need to update the documentation to include libxml2 on the (already very long) list of things Windows developers have to install in order to build llvm.<u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in">If you have knowledge of this, let me know. In the meantime, I'll attempt to bisect.<u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in">See below for the gory details.<u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in">Adrian.<u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in"><span style="font-size:7.5pt;font-family:"Courier New"">cmake -GNinja -DPYTHON_HOME="C:\Program Files\Python38" -DLLDB_PYTHON_HOME="C:\Program Files\Python38" -DPYTHON_EXECUTABLE="C:\Program Files\Python38\bin\python.exe"
-DPython3_ROOT_DIR="C:\Program Files\Python38" -DPython3_FIND_REGISTRY=LAST ..\..\llvm-project\llvm -DLLVM_ENABLE_ZLIB=OFF -DLLVM_ENABLE_PROJECTS="clang;lld;lldb" -DLLVM_TARGETS_TO_BUILD=X86 -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_COMPILER=D:/src/llvm/build/ninja/bin/clang-cl.exe
-DCMAKE_CXX_COMPILER=D:/src/llvm/build/ninja/bin/clang-cl.exe</span><u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in"><span style="font-size:10pt;font-family:"Courier New"">-- The C compiler identification is Clang 14.0.0 with MSVC-like command-line</span><br>
<span style="font-size:10pt;font-family:"Courier New"">-- The CXX compiler identification is Clang 14.0.0 with MSVC-like command-line</span><br>
<span style="font-size:10pt;font-family:"Courier New"">-- The ASM compiler identification is Clang</span><br>
<span style="font-size:10pt;font-family:"Courier New"">-- Found assembler: D:/src/llvm/build/ninja/bin/clang-cl.exe</span><br>
<span style="font-size:10pt;font-family:"Courier New"">-- Detecting C compiler ABI info</span><br>
<span style="font-size:10pt;font-family:"Courier New"">-- Detecting C compiler ABI info - failed</span><br>
<span style="font-size:10pt;font-family:"Courier New"">-- Check for working C compiler: D:/src/llvm/build/ninja/bin/clang-cl.exe</span><br>
<span style="font-size:10pt;font-family:"Courier New"">-- Check for working C compiler: D:/src/llvm/build/ninja/bin/clang-cl.exe - broken</span><br>
<span style="font-size:10pt;font-family:"Courier New"">CMake Error at C:/Program Files (x86)/Microsoft Visual Studio/2019/Professional/Common7/IDE/CommonExtensions/Microsoft/CMake/CMake/share/cmake-3.20/Modules/CMakeTestCCompiler.cmake:66 (message):</span><u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in"><span style="font-size:7.5pt;font-family:"Courier New""> The C compiler</span><u></u><u></u></p>
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"D:/src/llvm/build/ninja/bin/clang-cl.exe"<br>
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is not able to compile a simple test program.<br>
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It fails with the following output:<br>
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Change Dir: D:/src/llvm/build/selfhost/CMakeFiles/CMakeTmp<br>
<br>
Run Build Command(s):C:/PROGRA~2/MICROS~1/2019/PROFES~1/Common7/IDE/COMMON~1/MICROS~1/CMake/Ninja/ninja.exe cmTC_62af5 && [1/2] Building C object CMakeFiles\cmTC_62af5.dir\testCCompiler.c.obj<br>
[2/2] Linking C executable cmTC_62af5.exe<br>
FAILED: cmTC_62af5.exe<br>
cmd.exe /C "cd . && "C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin\cmake.exe" -E vs_link_exe --intdir=CMakeFiles\cmTC_62af5.dir --rc=C:\PROGRA~2\WI3CF2~1\10\bin\100183~1.0\x64\rc.exe
--mt=D:\src\llvm\build\ninja\bin\llvm-mt.exe --manifests -- D:\src\llvm\build\ninja\bin\lld-link.exe /nologo CMakeFiles\cmTC_62af5.dir\testCCompiler.c.obj /out:cmTC_62af5.exe /implib:cmTC_62af5.lib /pdb:cmTC_62af5.pdb /version:0.0 /machine:x64 /debug /INCREMENTAL
/subsystem:console kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib && cd ."<br>
MT: command "D:\src\llvm\build\ninja\bin\llvm-mt.exe /nologo /manifest CMakeFiles\cmTC_62af5.dir/intermediate.manifest /out:CMakeFiles\cmTC_62af5.dir/embed.manifest /notify_update" failed (exit code 0x1) with the following output:<br>
llvm-mt: error: no libxml2<br>
llvm-mt: ignoring unsupported 'notify_update' option</span><u></u><u></u></p>
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<p class="MsoNormal" style="margin-left:0.5in"><span style="font-size:7.5pt;font-family:"Courier New""> ninja: build stopped: subcommand failed.</span><u></u><u></u></p>
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