What is the cause for this invalid path issue when trying to run cpp protocol buffer compiler from CMake on Windows 10 and how can I solve it? - cmake

Question

I'm trying to build the aasdk project on a Windows 10 computer. To do this, I am attempting to run the following commands in the root of the git repo directory:
mkdir buildDir
cd buildDir
cmake ..\
cmake --build . --config Release
The last command is obviously the one that's failing. I get the following output when I run that command:
-- Selecting Windows SDK version 10.0.18362.0 to target Windows 10.0.19041.
-- Found libusb-1.0:
-- - Includes: C:/libusb-master/x64/Release
-- - Libraries: C:/libusb-master/x64/Release/lib/libusb-1.0.lib
-- Configuring done
-- Generating done
-- Build files have been written to: C:/aasdk-development/buildDir
Microsoft (R) Build Engine version 16.8.3+39993bd9d for .NET Framework
Copyright (C) Microsoft Corporation. All rights reserved.
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Microsoft\VC\v160\Microsoft.CppCommon.targets(200
,5): warning MSB8062: Custom build for item "C:\aasdk-development\buildDir\CMakeFiles\b2b8e2a3c1aae1e014a7c3c3f8aadde7\AVCha
nnelData.pb.h.rule" specifies invalid path "C:\aasdk-development\buildDir\aasdk_proto\protobuf::protoc" as an additional dep
endency. This may cause incremental build to work incorrectly. [C:\aasdk-development\buildDir\aasdk_proto\aasdk_proto.vcxpro
j]
...
Running cpp protocol buffer compiler on C:/aasdk-development/aasdk_proto/AVChannelData.proto
The filename, directory name, or volume label syntax is incorrect.
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Microsoft\VC\v160\Microsoft.CppCommon.targets(238
,5): error MSB8066: Custom build for 'C:\aasdk-development\buildDir\CMakeFiles\b2b8e2a3c1aae1e014a7c3c3f8aadde7\AVChannelDat
a.pb.h.rule;...' exited
with code 123. [C:\aasdk-development\buildDir\aasdk_proto\aasdk_proto.vcxproj]
Where ... is the same message repetead for each *.proto file inside aasdk_proto directory. From what I can tell, it seems it thinks some paths are invalid. What I can't tell, is which paths and in what way are they invalid.
After the first comment, I decided to check where it gets those paths. Below is the content of the CMakeLists.txt for protobuf, found in the aasdk_proto directory:
include(FindProtobuf)
find_package(Protobuf REQUIRED)
include_directories(${PROTOBUF_INCLUDE_DIR})
file(GLOB_RECURSE proto_files ${CMAKE_CURRENT_SOURCE_DIR}/*.proto)
protobuf_generate_cpp(proto_sources proto_headers ${proto_files})
add_library(aasdk_proto SHARED ${proto_headers} ${proto_sources})
target_link_libraries(aasdk_proto ${PROTOBUF_LIBRARIES})
Of interest is the 5th line which enumerates all the *.proto files in the relevant directory before calling protobuf_generate_cpp, the part which I believe to be causing the errors.
Adding message(STATUS ProtoFiles: ${proto_files}) after line 5 to print the paths yielded correct values, atleast to my eyes:
C:/aasdk-development/aasdk_proto/AbsoluteInputEventData.proto;C:/aasdk-development/aasdk_proto/AbsoluteInputEventData.proto;...
I replaced the forward slash with a backslash just for giggles, since that's how Windows likes them, but that didn't work.

Answer 1

I'm a bit late, but for anyone still having this problem, I ran into a similar issue while building CuraEngine, and found the cause. In my case, I had to set the path to protoc.exe with both variables PROTOC and Protobuf_PROTOC_EXECUTABLE. (I had only set PROTOC and CMake didn't throw any errors.)
I imagine the situation with aasdk must be similar. Some variable (probably PROTOBUF_PROTOC_EXECUTABLE?) that tells the location of protoc.exe must be missing.