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Marc Chevrier
69 lines
2.7 KiB
ReStructuredText
69 lines
2.7 KiB
ReStructuredText
CMAKE_LINK_LIBRARIES_STRATEGY
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-----------------------------
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.. versionadded:: 3.31
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Specify a strategy for ordering targets' direct link dependencies
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on linker command lines.
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The value of this variable initializes the :prop_tgt:`LINK_LIBRARIES_STRATEGY`
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target property of targets as they are created. Set that property directly
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to specify a strategy for a single target.
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CMake generates a target's link line using its :ref:`Target Link Properties`.
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In particular, the :prop_tgt:`LINK_LIBRARIES` target property records the
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target's direct link dependencies, typically populated by calls to
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:command:`target_link_libraries`. Indirect link dependencies are
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propagated from those entries of :prop_tgt:`LINK_LIBRARIES` that name
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library targets by following the transitive closure of their
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:prop_tgt:`INTERFACE_LINK_LIBRARIES` properties. CMake supports multiple
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strategies for passing direct and indirect link dependencies to the linker.
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Consider this example for the strategies below:
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.. code-block:: cmake
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add_library(A STATIC ...)
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add_library(B STATIC ...)
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add_library(C STATIC ...)
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add_executable(main ...)
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target_link_libraries(B PRIVATE A)
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target_link_libraries(C PRIVATE A)
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target_link_libraries(main PRIVATE A B C)
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The supported strategies are:
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``PRESERVE_ORDER``
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Entries of :prop_tgt:`LINK_LIBRARIES` always appear first and in their
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original order. Indirect link dependencies not satisfied by the
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original entries may be reordered and de-duplicated with respect to
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one another, but are always appended after the original entries.
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This may result in less efficient link lines, but gives projects
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control of ordering among independent entries. Such control may be
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important when intermixing link flags with libraries, or when multiple
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libraries provide a given symbol.
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This is the default.
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In the above example, this strategy computes a link line for ``main``
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by starting with its original entries ``A B C``, and then appends
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another ``A`` to satisfy the dependencies of ``B`` and ``C`` on ``A``.
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The final order is ``A B C A``.
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``REORDER``
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Entries of :prop_tgt:`LINK_LIBRARIES` may be reordered, de-duplicated,
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and intermixed with indirect link dependencies. This may result in
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more efficient link lines, but does not give projects any control of
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ordering among independent entries.
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In the above example, this strategy computes a link line for ``main``
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by re-ordering its original entries ``A B C`` to satisfy the
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dependencies of ``B`` and ``C`` on ``A``.
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The final order is ``B C A``.
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.. note::
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Regardless of the strategy used, the actual linker invocation for
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some platforms may de-duplicate entries based on linker capabilities.
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See policies :policy:`CMP0156` and :policy:`CMP0179`.
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