-----Original Message-----
From: Pat Marion <pat.mar...@kitware.com>
To: David Cole <dlrd...@aol.com>
Cc: themiwi <them...@gmail.com>; cmake <cmake@cmake.org>
Sent: Wed, Feb 6, 2013 8:34 am
Subject: Re: [CMake] Passing CMAKE_TOOLCHAIN_FILE on command line causes CMake
warning
I'd like you to try pasting the following text into a google search, so you can
appreciate how widespread the warning is, 257 results from lots of different
projects:
CMake Warning: Manually-specified variables were not used by the project:
CMAKE_TOOLCHAIN_FILE
Most of these projects are not going to incorporate workarounds. The warning
is confusing to lots of users, and they're already unsure of the while
crosscompiling thing, so seeing a warning adds uncertainty that they're doing
it right. Adding a workaround into the target project is not always possible
since you might not have commit access or are compiling a previously released,
stable version.
Pat
On Wed, Feb 6, 2013 at 10:51 PM, David Cole <dlrd...@aol.com> wrote:
If you don't want to see the warning, then also pass in --no-warn-unused-cli on
the command line.
--no-warn-unused-cli = Don't warn about command line options.
But that suppresses the warning for all unreferenced variables.
Or... add:
message(STATUS "CMAKE_TOOLCHAIN_FILE='${CMAKE_TOOLCHAIN_FILE}'")
to the project's CMakeLists.txt file so the variable is always referenced.
The point is: CMAKE_TOOLCHAIN_FILE is only read on the first configure. After
that point, all toolchain stuff is cached and the file is unnecessary for
subsequent configures.
That bug should just be closed as "won't fix" because it's not a bug. It's the
intended behavior, and there are multiple ways to avoid the legitimate warning.
Just my opinion,
D
-----Original Message-----
From: Pat Marion <pat.mar...@kitware.com>
To: Michael Wild <them...@gmail.com>
Cc: cmake <cmake@cmake.org>
Sent: Wed, Feb 6, 2013 7:23 am
Subject: Re: [CMake] Passing CMAKE_TOOLCHAIN_FILE on command line causes CMake
warning
That's a pretty messy workaround though, I think. ExternalProject_Add passes
in lots of variables, including ones that do not typically change, like
CMAKE_CXX_COMPILER. Why impose a special requirement on the
CMAKE_TOOLCHAIN_FILE variable? Would a patch to avoid the warning be a welcome
change, or is there a reason the warning should remain?
Pat
On Wed, Feb 6, 2013 at 9:52 PM, Michael Wild <them...@gmail.com> wrote:
Hi
On Wed, Feb 6, 2013 at 11:59 AM, Pat Marion <pat.mar...@kitware.com> wrote:
Hi,
I'm emailing about bug 13093 in the backlog. I found comments by Brad that
suggest it's a legitimate warning, but I'm not sure how a project could avoid
the warning.
By not specifying the toolchain file, for instance? If you have the problem in
conjunction with ExternalProject_Add, check whether the CMakeCache.txt file
exists in the build tree of the external project. If not, include the flag,
otherwise drop it.
My 2c
Michael
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I appreciate the widespread nature of "the problem." Really, I do. (If you do
the same search, but without CMAKE_TOOLCHAIN_FILE, you get 20,000+ results.)
The intent of the warning feature is to point out that you may have misspelled
a variable name, since usually, variables specified on the command line *are*
in fact, referenced during the configure or generate steps.
Unfortunately, the text of the warning does not say "you may have misspelled
this, double-check your spelling". Nor does it say the more clear "this
variable was not referenced at all by any of the CMakeLists code used during
configuration or generation". It could even say "reference the variable, or use
--no-warn-unused-cli to eliminate this warning" -- but it doesn't.
The other positive effect here is that it may point out that you're not using
all the variables that you think you're using. Therefore, you may be able to
simplify your command line, or your CMakeLists files.
I'm not a big fan of special-casing variable names for code like this. But if
CMAKE_TOOLCHAIN_FILE is really "special", then maybe that's the right call
here. You could certainly check if it's the same as the cached value, and only
warn if it's different. If you do add such a warning, use text something like
"start with a completely clean build tree if you are changing toolchain files"
when a difference is detected.
Cheers,
D
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