[cfe-dev] Building Clang from the distribution files - Git errors and VCSRevision.h

[Fletcher, John P via cfe-dev]

Hi

I am building LLVM and Clang from the distribution files using CMake, Ninja and gcc 7.1.  I can usually get a clean run on this.

I have noticed with Clang 9.0.0 that I get some error messages which seem to be related to a file VCSRevision.h and a search for git.  It declares this to be fatal and carries on!

There is very little in the documentation about how to build LLVM and Clang from a distribution as compared to cloning from Git.  I am wondering if the build is assuming that git init has been run in the build location.

I have read in the documentation about the CMake variable LLVM_APPEND_VC_REV which is defaulted to ON.  Should I be changing this value to OFF?

It would be helpful to have an official manual for building from a distribution along the lines of this unofficial one which I have found to be helpful although now dated: http://chiselapp.com/user/ttmrichter/repository/gng/doc/trunk/output/blog/2016/01-llvm-clang-missing-manual.html

Best wishes

John Fletcher

Building LLVM/Clang: The Missing Manual<http://chiselapp.com/user/ttmrichter/repository/gng/doc/trunk/output/blog/2016/01-llvm-clang-missing-manual.html>
LLVM and its attendant compiler project Clang are powerhouses in F/OSS. Unfortunately its attendant documentation is not such a powerhouse. Indeed its documentation for getting started with it is laughably terrible. Consider the "getting started" guide for LLVM. Now consider the equivalent document for Clang.
chiselapp.com


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