if protobuf compiler test_gemm compilation fails with: *** target pattern contains no '%'. Stop.

[berndporr]

It took me quite a while to fix this as the error message is completely opaque:

CMakeFiles/dlprim_onnx.dir/build.make:73: *** target pattern contains no '%'. Stop.
make[1]: *** [CMakeFiles/Makefile2:515: CMakeFiles/dlprim_onnx.dir/all] Error 2

cmake generates protobuf::protoc as a placeholder when the protoc is not found. See here: Ultimaker/libArcus#108 (comment)

It's fixed with installing the protobuf compiler:

sudo apt install protobuf-compiler

It would be good to check in the cmake script if the compiler exists but not sure how to do that!

[artyom-beilis]

Strange. FindProtobuf cmake does not even have a category for protobuf compiler. I expected it to fail building onnx code.

[berndporr]

Indeed strange. One would expect that failing as you said.