[cmake-developers] RFC: add version to project() call

Daniel Pfeifer daniel at pfeifer-mail.de
Tue Jan 14 14:11:02 EST 2014


2014/1/14 Matthew Woehlke <mw_triad at users.sourceforge.net>:
> On 2014-01-14 10:37, Brad King wrote:
>>
>> On 01/13/2014 01:38 PM, Alexander Neundorf wrote:
>>>
>>> does this require a policy now ?
>>>
>>> Somebody could set Foo_VERSION_MAJOR in the toplevel subdir, and have a
>>> project(Foo)
>>> call in a subdir, which would now unset Foo_VERSION_MAJOR.
>>> The same for PROJECT_VERSION_MAJOR, but this is maybe less likely.
>>
>>
>> I don't think project(Foo) needs to affect Foo_VERSION_* when no
>> VERSION argument is given (but should handle empty VERSION "").
>> It should still handle PROJECT_VERSION_* to ensure consistency
>> with PROJECT_NAME.  That may need a policy, but it will be tricky
>> because we need to know if the value came from a previous project()
>> call or a user set() in order to know when to trigger compatibility.
>>
>> Perhaps "project(... VERSION ...)" can set some cmMakefile variable
>> internally that says the project knows about versions so it is okay
>> project(Foo) calls to unset them in subdirs.  Then we won't need any
>> policy because there is no change in behavior without modifying the
>> project to add at least one VERSION to a project() command.
>
>
> While that sounds good for 99.9% of cases, what about the case of project A
> that includes project B, where B is not updated, but A decides to start
> using project(...VERSION...). Now if B was using PROJECT_VERSION internally,
> it is broken. (Note that I'm implying that B is e.g. a separate repository
> that may not be "as easy to update/fix as A".)
>
> That's an edge case though... not sure it's worth worrying about, but just
> saying...
>
> @Daniel, there is a CMAKE_PROJECT_NAME? I've always used just
> PROJECT_NAME... (Is PROJECT_NAME deprecated?) Anyway, while *hopefully* no
> one is setting e.g. CMAKE_PROJECT_VERSION there's still risk that they are.

http://cmake.org/cmake/help/v2.8.12/cmake.html#variable:CMAKE_PROJECT_NAME
http://cmake.org/cmake/help/v2.8.12/cmake.html#variable:PROJECT_NAME

The documentation for both variables is misleading. As far as I
understand it, PROJECT_NAME is the name of the current project, while
CMAKE_PROJECT_NAME us the name of the top-level project.
This comes in handy when projects are added with 'add_subdirectory()'.
If NOT CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME, the current project
is not built independently.



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