CMake build: "Error copying file "../../../bin/liblldb.dll" to "_lldb.pyd"

[jbsolomon]

Running a CMake build on Windows amd64 on release/14.x with:

• -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;lld;lldb;mlir"
• -DLLDB_ENABLE_PYTHON=OFF
• -DLLDB_ENABLE_LUA=ON

I was able to build 11, 12, and 13. The compiler is Clang 13.0 built from source on d7b669b and I am using PowerShell (but it also happens with cmd.exe.) No Visual Studio envars, no mingw. Ninja generator.

Unfortunately my terminal is unable to copy selections to the Windows clipboard.

Anyway, almost immediately the build fails on tools/lldb/CMakeFiles/lldb-lua.util, complaining that

cmd.exe /C "cd /D C:\llvm-build\llvm-project-14.0.0\build\lib\lua\5.3 && "C:\Program Files\CMake\bin\cmake.exe" -E copy ../../../bin/liblldb.dll _lldb.pyd"

fails to copy the file. I have verified this by running the command by hand, and indeed, this file is absent from the source directory.

Any pointers would be welcome!

[llvmbot]

@llvm/issue-subscribers-lldb

[DavidSpickett]

There are 2 references to that file in the codebase. One added by https://reviews.llvm.org/D108090 and one in ScriptInterpreterPython.cpp.

I don't know LUA at all but I'm assuming that .pyd isn't used for that, given https://docs.python.org/3/faq/windows.html#is-a-pyd-file-the-same-as-a-dll. If I had to guess, the Windows part of that linked change was not tested or was tested along with Python to make sure both worked. So the author happened to have both sets of files on their machine.

However I can't tell you what those files should be named, if indeed there are equivalents for LUA.

@JDevlieghere might know?

[JDevlieghere]

Yeah, it looks like it was copy/pasted from the Python CMake logic. I'll put up a patch.

[jbsolomon]

awesome @JDevlieghere, thank you so much for the quick response! is it possible to get this backported to release/14.x?

[jbsolomon]

BTW, on a cursory overview of that file, it does look like there may be other Python-related logic there (such as setting LLDB_LUA_INSTALL_PATH to a path with Python in the name....)

[JDevlieghere]

I came to the same conclusion. That leads me to believe nobody really tried using Lua as LLDB's scripting language on Windows. I'll need to build LLDB on Windows and see what needs to happen there for fix this properly.

[jbsolomon]

Lua is the most sensible option on Windows since it's so portable. Setting up the Python environment gets complicated fast.

[jbsolomon]

@JDevlieghere -- anything I can do to help get this shipped? it's blocking me from using the new stable version