LINK_LIBRARIES_STRATEGY¶
New in version 3.31.
Specify a strategy for ordering a target's direct link dependencies
on linker command lines. This property is initialized by the value of the
CMAKE_LINK_LIBRARIES_STRATEGY variable if it is set when a
target is created.
CMake generates a target's link line using its Target Link Properties.
In particular, the LINK_LIBRARIES target property records the
target's direct link dependencies, typically populated by calls to
target_link_libraries(). Indirect link dependencies are
propagated from those entries of LINK_LIBRARIES that name
library targets by following the transitive closure of their
INTERFACE_LINK_LIBRARIES properties. CMake supports multiple
strategies for nominally ordering direct and indirect link dependencies,
which are then filtered for Toolchain-Specific Behavior.
Consider this example for the strategies below:
add_library(A STATIC ...)
add_library(B STATIC ...)
add_library(C STATIC ...)
add_executable(main ...)
target_link_libraries(B PRIVATE A)
target_link_libraries(C PRIVATE A)
target_link_libraries(main PRIVATE A B C)
The supported strategies are:
REORDER_MINIMALLYEntries of
LINK_LIBRARIESalways appear first and in their original order. Indirect link dependencies not satisfied by the original entries may be reordered and de-duplicated with respect to one another, but are always appended after the original entries. This may result in less efficient link lines, but gives projects control of ordering among independent entries. Such control may be important when intermixing link flags with libraries, or when multiple libraries provide a given symbol.This is the default.
In the above example, this strategy computes a link line for
mainby starting with its original entriesA B C, and then appends anotherAto satisfy the dependencies ofBandConA. The nominal order produced by this strategy isA B C A.Note that additional filtering for Toolchain-Specific Behavior may de-duplicate
Aon the actual linker invocation in the generated build system, resulting in eitherA B CorB C A.REORDER_FREELYEntries of
LINK_LIBRARIESmay be reordered, de-duplicated, and intermixed with indirect link dependencies. This may result in more efficient link lines, but does not give projects any control of ordering among independent entries.In the above example, this strategy computes a link line for
mainby re-ordering its original entriesA B Cto satisfy the dependencies ofBandConA. The nominal order produced by this strategy isB C A.
Toolchain-Specific Behavior¶
After one of the above strategies produces a nominal order among
direct and indirect link dependencies, the actual linker invocation
in the generated build system may de-duplicate entries based on
platform-specific requirements and linker capabilities.
See policy CMP0156.
For example, if the REORDER_MINIMALLY strategy produces A B C A,
the actual link line may de-duplicate A as follows:
If
Ais a static library and the linker re-scans automatically, the first occurrence is kept, resulting inA B C. See policyCMP0179If
Ais a shared library on Windows, the first occurrence is kept, resulting inA B C.If
Ais a shared library on macOS or UNIX platforms, the last occurrence is kept, resulting inB C A.