This introduces the unset() command to make it easy to unset CMake
variables, environment variables, and CMake cache variables. Previously
it was not even possible to unset ENV or CACHE variables (as in
completely remove them). Changes based on patch from Philip Lowman.
See issue #7507.
Some native build tools, particularly those for cross compiling, may
have a limit on the length of the full path to an object file name that
is lower than the platform otherwise supports. This change allows the
limit to be set by the project toolchain file through the variable
CMAKE_OBJECT_PATH_MAX.
It is useful to be able to test if a target has been created. Often
targets are created only inside conditions. Rather than storing the
result of the condition manually for testing by other parts of the
project, it is much easier for the other parts to just test for the
target's existence. This will also be useful when find-modules start
reporting results with IMPORTED targets and projects want to test if a
certain target is available.
According to "man select" on Linux it is possible that select() lies
about data being ready on a pipe in some subtle cases. We deal with
this by switching to non-blocking i/o and checking for EAGAIN. See
issue #7180.
The LINK_INTERFACE_LIBRARIES target property may not contain the
"debug", "optimized", or "general" keywords. These keywords are
supported only by the target_link_libraries (and link_libraries) command
and are not a generic library list feature in CMake. When a user
attempts to add one of these keywords to the property value, we now
produce an error message that refers users to alternative means.
The LINK_INTERFACE_LIBRARIES property does not apply for STATIC
libraries. The IMPORTED_LINK_INTERFACE_LIBRARIES property does apply
for STATIC libraries. State both explicitly in the documentation.
Also, clarify that the per-configuration version of these properties
completely overrids the generic version.
The compatibility check to allow linking to modules should test for
CMake 2.2, not the unreleased 2.3. See issue #7500. Furthermore, the
message should be more clear about fixing the code instead of setting
CMAKE_BACKWARDS_COMPATIBILITY unless one is just trying to build an
existing project.
In the future some policies may be set to REQUIRED_IF_USED or
REQUIRED_ALWAYS. This change clarifies the error messages users receive
when violating the requirements.
When creating an IMPORTED target for a library that has been found on
disk, it may not be known whether the library is STATIC or SHARED.
However, the library may still be linked using the file found from disk.
Use of an IMPORTED target is still important to allow per-configuration
files to be specified for the library.
This change creates an UNKNOWN type for IMPORTED library targets. The
IMPORTED_LOCATION property (and its per-config equivalents) specifies
the location of the library. CMake makes no assumptions about the
library that cannot be inferred from the file on disk. This will help
projects and find-modules import targets found on disk or specified by
the user.
In switch statements that deal with only a few target types, use a
'default' case for the remaining target types instead of listing them
explicitly. This will make it easier to add more types in the future.
Rename the recently added INTERFACE mode of the target_link_libraries()
command to LINK_INTERFACE_LIBRARIES. This makes it much more distinct
from a normal call to the command, and clearly states its connection to
the property of the same name. Also require the option to appear
immediately after the target name to make it a mode rather than an
option.
It is likely that projects or CMake modules in the future will need to
check the value of a policy setting. For example, if we add a policy
that affects the results of FindXYZ.cmake modules, the module code will
need to be able to check the policy.
During installation the RPATH and RUNPATH entries of ELF binaries are
edited to match the user specification. Usually either one entry is
present or both entries refer to the same string literal. In the case
that they are both present and refer to separate string literals we need
to update both. I have never seen this case in practice, but we should
do this just in case.
Removal of the RPATH and RUNPATH from ELF binaries must work when both
entries are present. Both entries should be removed. Previously only
one would be removed and the other would be blanked because it pointed
at the same string which was zeroed. This fixes gentoo bug number
224901.
Create an INTERFACE option to the target_link_libraries command to help
set the LINK_INTERFACE_LIBRARIES and LINK_INTERFACE_LIBRARIES_DEBUG
properties. This will help users specify link interfaces using
variables from Find*.cmake modules that include the 'debug' and
'optimized' keywords.
Brad King
David Cole
Bill Hoffman
Alexander Neundorf