[cpp] CMake ABI/SONAME versioning does not appear to work as expected

[musicinmybrain]

👓 What did you see?

Based on #320 (comment) and #328, I expected the SONAME version for both C and C++ shared libraries to be 32 for https://github.com/cucumber/gherkin/releases/tag/v32.0.0, using

gherkin/c/VERSION

Line 1 in 275322f

32.0.0

and

gherkin/cpp/VERSION

Line 1 in 275322f

32.0.0

Indeed, this was the case for the C++ library,

libgherkin.so -> libgherkin.so.32
libgherkin.so.32 -> libgherkin.so.32.0.0
libgherkin.so.32.0.0

but not for the C++ library,

libcucumber_gherkin.so -> libcucumber_gherkin.so.30
libcucumber_gherkin.so.30 -> libcucumber_gherkin.so.30.0.4
libcucumber_gherkin.so.30.0.4

✅ What did you expect to see?

I expected to see the C++ shared library versioned based on cpp/VERSION, just as the C shared library is now versioned based on c/VERSION, which would have resulted in:

libcucumber_gherkin.so -> libcucumber_gherkin.so.32
libcucumber_gherkin.so.32 -> libcucumber_gherkin.so.32.0.0
libcucumber_gherkin.so.32.0.0

📦 Which tool/library version are you using?

cucumber/gherkin 32.0.0; no other versions should be relevant

🔬 How could we reproduce it?

Build cpp/ with CMake in the usual way, setting -DBUILD_SHARED_LIBS:BOOL=ON. Observe that this produces:

${builddir}/src/lib/gherkin/libcucumber_gherkin.so.30.0.4
${builddir}/src/lib/gherkin/libcucumber_gherkin.so.30
${builddir}/src/lib/gherkin/libcucumber_gherkin.so

when the contents of VERSION are

32.0.0

📚 Any additional context?

It looks like cpp/CMakeLists.txt needs the same boilerplate as c/CMakeLists.txt:

gherkin/c/CMakeLists.txt

Lines 1 to 18 in 275322f

	set(VERSION 27.0.2)
	if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/VERSION")
	file(STRINGS "VERSION" LINES)
	list(GET LINES 0 VERSION)
	endif()
	# Crude Semver parsing
	if("${VERSION}" MATCHES "^([^\\.]+)\\.([^\\.]+)\\.([^\\.]+)$")
	set(VER_MAJOR ${CMAKE_MATCH_1})
	set(VER_MINOR ${CMAKE_MATCH_2})
	set(VER_PATCH ${CMAKE_MATCH_3})
	else()
	message(FATAL_ERROR "unable to parse version: ${VERSION}")
	endif()
	cmake_minimum_required(VERSION 3.0)
	PROJECT(gherkin VERSION ${VERSION} LANGUAGES C)

[musicinmybrain]

We also have this in the C library:

gherkin/c/CMakeLists.txt

Lines 91 to 96 in 275322f

	set_target_properties(
	gherkin
	PROPERTIES
	VERSION ${VERSION}
	SOVERSION ${VER_MAJOR}
	)

and this in the C++ library:

gherkin/cpp/src/lib/gherkin/CMakeLists.txt

Lines 34 to 42 in 275322f

	set_target_properties(
	cucumber_gherkin_lib
	PROPERTIES
	CXX_STANDARD 20
	VERSION 30.0.4
	SOVERSION 30
	EXPORT_NAME gherkin
	OUTPUT_NAME cucumber_gherkin
	)

so it looks like those hard-coded version numbers need adjusting as well.

This seems to make things work as I expected them to: #376