find_package(PDI) cannot be called twice

[tpadioleau]

Hello, I found that find_package(PDI) cannot be called twice. This can be problematic for complex dependencies. For example, assuming a package called APackageThatDependsOnPDI executes find_dependency(PDI 1.6...<2), the following cmake snippet returns an error in cmake >=3.26:

find_package(APackageThatDependsOnPDI)
find_package(PDI)

The error I get is add_executable cannot create imported target "PDI::pdirun" because another target with the same name already exists.. Of course one workaround is to add if/else guards but it adds more complexity on the user side and I don't think it is a common practice to do so.

Also curiously the following snippet does not return an error:

find_package(PDI)
find_package(APackageThatDependsOnPDI)

I think the reason comes from the line

pdi/pdi/cmake/PDIConfig.cmake.in

Line 29 in 6415fbf

include(${CMAKE_CURRENT_LIST_DIR}/CMakeFindDependencyMacro.cmake)

that includes a version of the module CMakeFindDependencyMacro that is not in line with the change of behavior introduced in 3.26, see https://cmake.org/cmake/help/latest/module/CMakeFindDependencyMacro.html.