Fuzzer: CMake configuration failed for protobuf - fuzzer unbuildable

[bwlodarcz]

Overview
The way described in README.md of building spirv-fuzzer doesn't work.
It's resulting with an error in protobuf v3.13.0.1:

CMake Error at external/CMakeLists.txt:182 (add_subdirectory):
  The source directory

    SPIRV-Tools/external/protobuf

  does not contain a CMakeLists.txt file.

and indeed it doesn't have CMakeLists.txt.

I checked also the HEAD version of protobuf with --recurse-submodules (needed for abseil). In this case error was:

CMake Error in source/fuzz/CMakeLists.txt:
  export called with target "SPIRV-Tools-fuzz" which requires target
  "libprotobuf" that is not in any export set.

Environment
OS: Linux
CMake Version: 3.25.3

Steps to reproduce
For v.3.13.0.1:

1. git clone --depth=1 --branch v3.13.0.1 https://github.com/protocolbuffers/protobuf external/protobuf
2. cmake -G Ninja -B build -DCMAKE_BUILD_TYPE=Debug -DSPIRV_BUILD_FUZZER=ON .

For HEAD:

1. git clone --depth=1 --recurse-submodules https://github.com/protocolbuffers/protobuf external/protobuf
2. cmake -G Ninja -B build -DCMAKE_BUILD_TYPE=Debug -DSPIRV_BUILD_FUZZER=ON .

[s-perron]

We have trouble building using the latest protobuf. We recommend you use git-sync-deps to checkout the submodules to get the version of each submodule that we use and test. See https://github.com/KhronosGroup/SPIRV-Tools?tab=readme-ov-file#getting-the-source. I just tested it on the latest main, and it work on linux.

Since there is nobody supporting the fuzzer anymore, there is nobody to do the work to try to update to the latest protobuf. We would accept a contribution from the community, but will not be doing it ourselves.