Add project name to CMake status message.

[paulcaprioli]

When building benchmark as part of a larger CMake project, the meaning of the following status message is not clear:

-- Version: 1.8.0

This patch identifies Google benchmark as the project to which the version refers:

-- Google benchmark version: 1.8.0

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[LebedevRI]

I think there was some way to prefix all cmake on-screen output for sub-projects with a custom prefix?

But regardless, i think this probably makes sense, at least it's rather unintrusive.

[paulcaprioli]

Thanks, Roman, I was unaware of cmake --log-context, which is useful if a larger project does something like this:

list(APPEND CMAKE_MESSAGE_CONTEXT "benchmark")
add_subdirectory(benchmark)
list(POP_BACK CMAKE_MESSAGE_CONTEXT)

I still think this PR makes sense, but I don't think I want to bother with the CLA process for such a trivial patch. If someone who has completed it wishes to add the words "Google benchmark" to the message string, I think that would be nice. I'm not a lawyer, and this is not legal advice, but I would venture to guess that Google has the right to add its name to the message string without my signature on a CLA.

[dmah42]

thanks, i created a similar patch.

[paulcaprioli]

If Google Benchmark is included in a project that uses git, then git naturally retrieves the git version of the enclosing project. So, for example, one might see the following messages printed with the latest benchmark code:

git version: v0.1.0-32-g302c23a7-dirty normalized to 0.1.0.32
Google Benchmark version: 0.1.0.32

Now, maybe I should not be including a copy of Google Benchmark directly in my project, and I am OK if this is not something you want to support.

On the other hand, perhaps you might wish to change:

message(STATUS "Google Benchmark version: ${VERSION}")

to

message(STATUS "Google Benchmark version: ${benchmark_VERSION}")

since the git version is reported on the previous line anyway.

Regardless, I wish to thank Google and the various volunteers for creating and maintaining this project.

--Paul

[LebedevRI]

The problem is as long it is determined from the git tag, it will always be detected incorrectly in that situation, regardless of how you name that variable.

[paulcaprioli]

My suggestion for that status message is to ignore the information retrieved from the git tag. In this project's CMakelists.txt file, the git tag is set in GIT_VERSION and, if nonzero, copied into VERSION. The variable benchmark_VERSION is set at the top of the file by the project() function:

project (benchmark VERSION 1.8.3 LANGUAGES CXX)

Some short documentation is found at:

https://cmake.org/cmake/help/latest/variable/PROJECT-NAME_VERSION.html