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IDProjectCategoryView StatusDate SubmittedLast Update
0014838CMakeCMakepublic2014-03-25 16:212016-06-10 14:31
ReporterNico Schlömer 
Assigned ToKitware Robot 
PrioritynormalSeverityminorReproducibilityalways
StatusclosedResolutionmoved 
PlatformOSOS Version
Product Version 
Target VersionFixed in Version 
Summary0014838: INSTALL(EXPORT ...) sets IMPORTED_LINK_INTERFACE_LIBRARIES_* differently from linker
DescriptionWhen linking a library against, say, liblapack.so,

TARGET_LINK_LIBRARIES(mytarget lapack)

the link line will contain something along the lines of `/usr/lib/liblapack.so` (mostly a symlink), which the linker will correctly resolve to wherever the actual LAPACK binary sits; e.g.,

$ ldd /opt/trilinos/lib/libepetra.so
[...]
    liblapack.so.3gf => /usr/lib/liblapack.so.3gf (0x00007fae46c64000)
[...]

When using CMake's INSTALL(EXPORT ...) functionality, the exported files will contain `IMPORTED_LINK_INTERFACE_LIBRARIES_<build type>` with LAPACK as appearing on the link line, e.g.,

set_property(TARGET epetra APPEND PROPERTY IMPORTED_CONFIGURATIONS RELWITHDEBINFO)
set_target_properties(epetra PROPERTIES
  IMPORTED_LINK_INTERFACE_LIBRARIES_RELWITHDEBINFO "/usr/lib/liblapack.so"
  IMPORTED_LOCATION_RELWITHDEBINFO "${_IMPORT_PREFIX}/lib/libepetra.so.11.7"
  IMPORTED_SONAME_RELWITHDEBINFO "libepetra.so.11"
  )

This poses problems whenever you use this exported information since it requires the symlink /usr/lib/liblapack.so to exist when really all you need is /usr/lib/liblapack.so.3gf.

A typical case for where this causes conflicts is Debian. Here, the former (/usr/lib/liblapack.so) is part of liblapack-dev, the latter (/usr/lib/liblapack.so.3gf) of the separate package liblapack.

I suppose the exported information should reflect as accurately as possible what is actually required by the library and thus follow the symlinks just like the linker does.
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Issue History
Date ModifiedUsernameFieldChange
2014-03-25 16:21Nico SchlömerNew Issue
2014-03-25 21:51Ben BoeckelNote Added: 0035514
2014-03-26 06:18Nico SchlömerNote Added: 0035517
2014-03-26 08:38Brad KingNote Added: 0035518
2016-06-10 14:29Kitware RobotNote Added: 0042518
2016-06-10 14:29Kitware RobotStatusnew => resolved
2016-06-10 14:29Kitware RobotResolutionopen => moved
2016-06-10 14:29Kitware RobotAssigned To => Kitware Robot
2016-06-10 14:31Kitware RobotStatusresolved => closed

Notes
(0035514)
Ben Boeckel   
2014-03-25 21:51   
The export file should also be part of the -dev package also, so there should be no problem here (e.g., how are you using liblapack without its headers?)
(0035517)
Nico Schlömer   
2014-03-26 06:18   
If libA uses LAPACK and only includes LAPACK's headers and functions in its source files, libA doesn't export an interface to LAPACK and building against libA (with its headers in libA-dev) doesn't require knowledge of the LAPACK interface, i.e., liblapack-dev.

I suppose a fundamental question here is: How does CMake determine if libA provides an interface to LAPACK? In other words: Why does CMake tag the LAPACK-dependecy as IMPORTED_LINK_INTERFACE_LIBRARIES_RELWITHDEBINFO instead of IMPORTED_LINK_DEPENDENT_LIBRARIES_RELWITHDEBINFO?
(0035518)
Brad King   
2014-03-26 08:38   
Read the documentation of target_link_libraries to see how it decides whether a dependency is in the interface or not. The preferred method has changed recently so see documentation for each version:

 v3.0: http://www.cmake.org/cmake/help/v3.0/command/target_link_libraries.html [^]
 v2.8.12: http://www.cmake.org/cmake/help/v2.8.12/cmake.html#command:target_link_libraries [^]
 v2.8.11: http://www.cmake.org/cmake/help/v2.8.11/cmake.html#command:target_link_libraries [^]

Quick answer:

 target_link_libraries(mytarget PRIVATE lapack)

or to work with CMake versions older than 2.8.12:

 target_link_libraries(mytarget LINK_PRIVATE lapack)
(0042518)
Kitware Robot   
2016-06-10 14:29   
Resolving issue as `moved`.

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