[package] Qt/5.15.2: Cmake doesn't export the versionless targets

[tcanabrava]

This is important for Qt5 / 6 compatibility.

https://doc-snapshots.qt.io/qt6-dev/cmake-qt5-and-qt6-compatibility.html

CMake Error at cmake/AddDualTargetLibrary.cmake:61 (add_library):
Target "tet_exec" links to target "Qt::Gui" but the target was not
found. Perhaps a find_package() call is missing for an IMPORTED target, or
an ALIAS target is missing?
Call Stack (most recent call first):
CMakeLists.txt:5

Steps to reproduce (Include if Applicable)

Create a Qt5 project for cmake.
Use the versionless Target:

add_executable(test main.cpp)
target_link_libraries(test Qt::Core)

[tcanabrava]

This also affects Qt6

[ericLemanissier]

I think conan is not able to generate targets in several namespaces : https://docs.conan.io/en/latest/reference/generators/cmake_find_package.html
It may be already reported in conan-io/conan. If not, it's worth reporting.

[SpaceIm]

I forgot to answer to this thread: you can emulate any target with a custom CMake module created at package() time, and added to build_modules in package_info(). It's tedious, but it works.

Most recipes using this trick create non namespaced targets, but you can perfectly create custom namespaced targets.
Take a look at openexr recipe:

conan-center-index/recipes/openexr/2.x/conanfile.py

Lines 98 to 226 in e1d9d8e

	self._create_cmake_module_alias_targets(
	os.path.join(self.package_folder, self._module_file_rel_path),
	{
	"IlmBase::IlmBaseConfig": "OpenEXR::IlmBaseConfig",
	"IlmBase::Half": "OpenEXR::Half",
	"IlmBase::Iex": "OpenEXR::Iex",
	"IlmBase::IexMath": "OpenEXR::IexMath",
	"IlmBase::IMath": "OpenEXR::IMath",
	"IlmBase::IlmThread": "OpenEXR::IlmThread",
	}
	)
	@staticmethod
	def _create_cmake_module_alias_targets(module_file, targets):
	content = ""
	for alias, aliased in targets.items():
	content += textwrap.dedent("""\
	if(TARGET {aliased} AND NOT TARGET {alias})
	add_library({alias} INTERFACE IMPORTED)
	set_property(TARGET {alias} PROPERTY INTERFACE_LINK_LIBRARIES {aliased})
	endif()
	""".format(alias=alias, aliased=aliased))
	tools.save(module_file, content)
	@property
	def _module_subfolder(self):
	return os.path.join("lib", "cmake")
	@property
	def _module_file_rel_path(self):
	return os.path.join(self._module_subfolder,
	"conan-official-{}-targets.cmake".format(self.name))
	def package_info(self):
	# FIXME: we should generate 2 CMake config files: OpenEXRConfig.cmake and IlmBaseConfig.cmake
	# waiting an implementation of https://github.com/conan-io/conan/issues/9000
	self.cpp_info.names["cmake_find_package"] = "OpenEXR"
	self.cpp_info.names["cmake_find_package_multi"] = "OpenEXR"
	self.cpp_info.names["pkg_config"] = "openexr_full_package" # not official, we want to avoid clash with OpenEXR.pc generated by IlmImf component
	openexr_version = tools.Version(self.version)
	lib_suffix = "-{}_{}".format(openexr_version.major, openexr_version.minor)
	if self.settings.build_type == "Debug":
	lib_suffix += "_d"
	include_dir = os.path.join("include", "OpenEXR")
	# IlmImfConfig
	self.cpp_info.components["openexr_ilmimfconfig"].names["cmake_find_package"] = "IlmImfConfig"
	self.cpp_info.components["openexr_ilmimfconfig"].names["cmake_find_package_multi"] = "IlmImfConfig"
	self.cpp_info.components["openexr_ilmimfconfig"].includedirs.append(include_dir)
	# IlmImf
	self.cpp_info.components["openexr_ilmimf"].names["cmake_find_package"] = "IlmImf"
	self.cpp_info.components["openexr_ilmimf"].names["cmake_find_package_multi"] = "IlmImf"
	self.cpp_info.components["openexr_ilmimf"].names["pkg_config"] = "OpenEXR"
	self.cpp_info.components["openexr_ilmimf"].includedirs.append(include_dir)
	self.cpp_info.components["openexr_ilmimf"].libs = ["IlmImf{}".format(lib_suffix)]
	self.cpp_info.components["openexr_ilmimf"].requires = [
	"openexr_ilmimfconfig", "ilmbase_iex", "ilmbase_half",
	"ilmbase_imath", "ilmbase_ilmthread", "zlib::zlib",
	]
	# IlmImfUtil
	self.cpp_info.components["openexr_ilmimfutil"].names["cmake_find_package"] = "IlmImfUtil"
	self.cpp_info.components["openexr_ilmimfutil"].names["cmake_find_package_multi"] = "IlmImfUtil"
	self.cpp_info.components["openexr_ilmimfutil"].includedirs.append(include_dir)
	self.cpp_info.components["openexr_ilmimfutil"].libs = ["IlmImfUtil{}".format(lib_suffix)]
	self.cpp_info.components["openexr_ilmimfutil"].requires = ["openexr_ilmimfconfig", "openexr_ilmimf"]
	# IlmBaseConfig
	self.cpp_info.components["ilmbase_ilmbaseconfig"].names["cmake_find_package"] = "IlmBaseConfig"
	self.cpp_info.components["ilmbase_ilmbaseconfig"].names["cmake_find_package_multi"] = "IlmBaseConfig"
	self.cpp_info.components["ilmbase_ilmbaseconfig"].builddirs.append(self._module_subfolder)
	self.cpp_info.components["ilmbase_ilmbaseconfig"].build_modules["cmake_find_package"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_ilmbaseconfig"].build_modules["cmake_find_package_multi"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_ilmbaseconfig"].includedirs.append(include_dir)
	# Half
	self.cpp_info.components["ilmbase_half"].names["cmake_find_package"] = "Half"
	self.cpp_info.components["ilmbase_half"].names["cmake_find_package_multi"] = "Half"
	self.cpp_info.components["ilmbase_half"].builddirs.append(self._module_subfolder)
	self.cpp_info.components["ilmbase_half"].build_modules["cmake_find_package"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_half"].build_modules["cmake_find_package_multi"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_half"].includedirs.append(include_dir)
	self.cpp_info.components["ilmbase_half"].libs = ["Half{}".format(lib_suffix)]
	self.cpp_info.components["ilmbase_half"].requires = ["ilmbase_ilmbaseconfig"]
	# Iex
	self.cpp_info.components["ilmbase_iex"].names["cmake_find_package"] = "Iex"
	self.cpp_info.components["ilmbase_iex"].names["cmake_find_package_multi"] = "Iex"
	self.cpp_info.components["ilmbase_iex"].builddirs.append(self._module_subfolder)
	self.cpp_info.components["ilmbase_iex"].build_modules["cmake_find_package"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_iex"].build_modules["cmake_find_package_multi"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_iex"].includedirs.append(include_dir)
	self.cpp_info.components["ilmbase_iex"].libs = ["Iex{}".format(lib_suffix)]
	self.cpp_info.components["ilmbase_iex"].requires = ["ilmbase_ilmbaseconfig"]
	# IexMath
	self.cpp_info.components["ilmbase_iexmath"].names["cmake_find_package"] = "IexMath"
	self.cpp_info.components["ilmbase_iexmath"].names["cmake_find_package_multi"] = "IexMath"
	self.cpp_info.components["ilmbase_iexmath"].builddirs.append(self._module_subfolder)
	self.cpp_info.components["ilmbase_iexmath"].build_modules["cmake_find_package"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_iexmath"].build_modules["cmake_find_package_multi"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_iexmath"].includedirs.append(include_dir)
	self.cpp_info.components["ilmbase_iexmath"].libs = ["IexMath{}".format(lib_suffix)]
	self.cpp_info.components["ilmbase_iexmath"].requires = ["ilmbase_ilmbaseconfig", "ilmbase_iex"]
	# IMath
	self.cpp_info.components["ilmbase_imath"].names["cmake_find_package"] = "IMath"
	self.cpp_info.components["ilmbase_imath"].names["cmake_find_package_multi"] = "IMath"
	self.cpp_info.components["ilmbase_imath"].builddirs.append(self._module_subfolder)
	self.cpp_info.components["ilmbase_imath"].build_modules["cmake_find_package"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_imath"].build_modules["cmake_find_package_multi"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_imath"].includedirs.append(include_dir)
	self.cpp_info.components["ilmbase_imath"].libs = ["Imath{}".format(lib_suffix)]
	self.cpp_info.components["ilmbase_imath"].requires = ["ilmbase_ilmbaseconfig", "ilmbase_half", "ilmbase_iexmath"]
	# IlmThread
	self.cpp_info.components["ilmbase_ilmthread"].names["cmake_find_package"] = "IlmThread"
	self.cpp_info.components["ilmbase_ilmthread"].names["cmake_find_package_multi"] = "IlmThread"
	self.cpp_info.components["ilmbase_ilmthread"].builddirs.append(self._module_subfolder)
	self.cpp_info.components["ilmbase_ilmthread"].build_modules["cmake_find_package"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_ilmthread"].build_modules["cmake_find_package_multi"] = [self._module_file_rel_path]
	self.cpp_info.components["ilmbase_ilmthread"].includedirs.append(include_dir)
	self.cpp_info.components["ilmbase_ilmthread"].libs = ["IlmThread{}".format(lib_suffix)]
	self.cpp_info.components["ilmbase_ilmthread"].requires = ["ilmbase_ilmbaseconfig", "ilmbase_iex"]
	if self.settings.os in ["Linux", "FreeBSD"]:
	self.cpp_info.components["ilmbase_ilmthread"].system_libs.append("pthread")

[perseoGI]

Hi there,
I was reviewing old issues and I have come across this one.
The qt/5.15.2 version is no longer supported by Conan Center Index.

I'm closing this issue as this recipe has suffer plenty of modifications since this issue was reported.
If for some reason the problem remains nowadays, do not hesitate to reopen this issue or create a new ticket with updated information, preferably using conan v2.

Happy coding 🐸

[SpaceIm]

@perseoGI I think it should not be closed, this issue has not been fixed.

[SpaceIm]

I've opened #25198

[perseoGI]

Okey thanks for opening an updated issue!

[SpaceIm]

It's not an updated issue but a PR fixing this issue.

[perseoGI]

My sorry, really early in the morning hehe, thanks for your contribution @SpaceIm