[CMake] Package installation conundrum

[Michael Wild]

On 05/08/2012 11:13 PM, Dave Abrahams wrote:
> 
> on Tue May 08 2012, Alexander Neundorf <a.neundorf-work-hi6Y0CQ0nG0-AT-public.gmane.org> wrote:
> 
>> On Tuesday 08 May 2012, Dave Abrahams wrote:
>>
>>> Here's another one!
>>>
>>> Scenario:
>>>
>>> * I am running CMake under 0install to build and install libraries
>>>
>>> * Each library builds a package SomePackage for the library binaries
>>> and another package SomePackage-dev for the library headers (and
>>> import libraries on Windows)
>>>
>>> * The FindSomePackage.cmake file is part of the -dev package
>>>
>>> * After building, 0install moves each package's build products into a
>>> mostly-unpredictable subdirectory of its otherwise-read-only "cache"
>>> (~/.cache/0install.net/). The subdirectory's name is determined by a
>>> hash of the files.
>>>
>>> * To get this working, I followed the scheme discussed here:
>>>
>>> http://news.gmane.org/find-root.php?message_id=%3cm2lil6s8jq.fsf%40pluto.l
>>> uannocracy.com%3e
>>>
>>> Summary:
>>>
>>> 1. Create a 0install "SomePackage-preinstall" package. Building this
>>> package involves CMake building and installing both SomePackage and
>>> SomePackage-dev into separate subdirectories (main/ and dev/) of
>>> some prefix. 0install thereafter moves the whole directory tree
>>> into its cache in a directory called sha1=someuglyhash
>>>
>>> 2. SomePackage's 0installation procedure is to copy
>>> sha1=someuglyhash/main/ into its distribution directory (which then ends
>>> up in
>>> ~/.cache/0install.net/sha1=otheruglyhash)
>>>
>>> 3. SomePackage-dev's 0installation procedure is to copy
>>> sha1=someuglyhash/dev/ into its distribution directory
>>>
>>> Problem: FindSomePackageConfig.cmake now has the wrong path to the
>>> library binaries.
>>>
>>> Any help most appreciated.
>>
>> Can you please summarize what you actually want to achieve ?
> 
> Well, I tried to, above.
> 
> In short, I want to create separate main and -dev packages without
> building twice, under the constraints imposed by 0install.
> 
>> Do you say that libFoo installs a FindFoo.cmake as part of libFoo-devel ?
>>
>> If that's the case, then this is wrong.
> 
> I'm sorry, that *is* wrong.  It installs a FooConfig.cmake as part of libFoo.devel
> 
>> FindFoo.cmake must be part of the using software, not of the software to be
>> searched.
>>
>> Why do you have to find the installed library in this cache directory
>> ?
> 
> Because, in a 0install world, that's where things go when you "install"
> them.
> 


Ok, how you do it along these lines:

CMakeLists.txt:
#-------------- BOF

cmake_minimum_required(VERSION 2.8 FATAL_ERROR)
project(Foo)

set(FOO_VERSION 1.2.3)

# initialize (absolute) installation directory variables
set(INSTALL_BIN_DIR bin CACHE PATH "Install path for binaries")
set(INSTALL_LIB_DIR lib CACHE PATH "Install path for libraries")
set(INSTALL_INCLUDE_DIR include CACHE PATH "Install path for headers")
# this is for UNIX systems, see docs of find_package() for the search
# paths on APPLE and WIN32
set(INSTALL_CMAKE_DIR lib/foo-${FOO_VERSION}/cmake CACHE PATH
  "Install path for CMake files")
foreach(t BIN LIB INCLUDE CMAKE)
  if(NOT IS_ABSOLUTE ${INSTALL_${t}_DIR})
    set(INSTALL_${t}_DIR ${CMAKE_INSTALL_PREFIX}/${INSTALL_${t}_DIR})
  endif()
  mark_as_advanced(INSTALL_${t}_DIR)
endforeach()

# configure FooConfig.cmake and friends. FooConfig.cmake must be able
# to locate FooExports.cmake and FOO_INCLUDE_DIR relative to its own
# directory without using absolute paths.
configure_file(cmake/FooConfig.cmake.in
  ${PROJECT_BINARY_DIR}/FooConfig.cmake @ONLY)
configure_file(cmake/FooConfigVersion.cmake.in
  ${PROJECT_BINARY_DIR}/FooConfigVersion.cmake @ONLY)

# configure the headers into the build tree so the package can be used
# without installing it and not hard-coding the source/build directory
# information into FooConfig.cmake
configure_file(include/foo.h
  ${PROJECT_BINARY_DIR}/include/foo.h COPYONLY)

# build targets
add_library(foo src/foo.cpp include/foo.h)
set_target_properties(foo PROPERTIES
  PUBLIC_HEADER include/foo.h
  VERSION ${FOO_VERSION}
  SOVERSION 1.0)
add_executable(bar bar.cpp)
target_link_libraries(bar foo)

# install targets and files
install(TARGETS foo bar
  EXPORT FooExports
  RUNTIME DESTINATION ${INSTALL_BIN_DIR} COMPONENT bin
  LIBRARY DESTINATION ${INSTALL_LIB_DIR} COMPONENT bin
  ARCHIVE DESTINATION ${INSTALL_LIB_DIR} COMPONENT dev
  PUBLIC_HEADER DESTINATION ${INSTALL_INCLUDE_DIR} COMPONENT dev)

install(FILES
  ${PROJECT_BINARY_DIR}/FooConfig.cmake
  ${PROJECT_BINARY_DIR}/FooConfigVersion.cmake
  DESTINATION ${INSTALL_CMAKE_DIR} COMPONENT dev)

# export targets to build and install tree
export(TARGETS foo bar NAMESPACE Foo_
  FILE ${PROJECT_BINARY_DIR}/FooExports.cmake)
export(PACKAGE Foo)

install(EXPORT FooExports
  DESTINATION ${INSTALL_CMAKE_DIR}
  NAMESPACE Foo_
  COMPONENT dev)

#-------------- EOF


With such a setup, you do something like the following for the
installation into the cache directories:

mkdir /path/to/build-tree
cd /path/to/build-tree
cmake /path/to/source-tree
make
DESTDIR=/path/to/bin-cache cmake -DCOMPONENT=bin -P cmake_install.cmake
DESTDIR=/path/to/dev-cache cmake -DCOMPONENT=dev -P cmake_install.cmake


Note that the -D options must be *before*the -P option, otherwise the
definitions will not be passed to the cmake_install.cmake script.

Now you have everything installed into different cache directories, but
still containing correct path information for the final installation
that is to be performed by 0install.