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Diffstat (limited to 'docs/CMakePrimer.rst')
| -rw-r--r-- | docs/CMakePrimer.rst | 27 |
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diff --git a/docs/CMakePrimer.rst b/docs/CMakePrimer.rst index 1e3a09e4d98a..c29d627ee62c 100644 --- a/docs/CMakePrimer.rst +++ b/docs/CMakePrimer.rst @@ -112,33 +112,6 @@ In this example the ``extra_sources`` variable is only defined if you're targeting an Apple platform. For all other targets the ``extra_sources`` will be evaluated as empty before add_executable is given its arguments. -One big "Gotcha" with variable dereferencing is that ``if`` commands implicitly -dereference values. This has some unexpected results. For example: - -.. code-block:: cmake - - if("${SOME_VAR}" STREQUAL "MSVC") - -In this code sample MSVC will be implicitly dereferenced, which will result in -the if command comparing the value of the dereferenced variables ``SOME_VAR`` -and ``MSVC``. A common workaround to this solution is to prepend strings being -compared with an ``x``. - -.. code-block:: cmake - - if("x${SOME_VAR}" STREQUAL "xMSVC") - -This works because while ``MSVC`` is a defined variable, ``xMSVC`` is not. This -pattern is uncommon, but it does occur in LLVM's CMake scripts. - -.. note:: - - Once the LLVM project upgrades its minimum CMake version to 3.1 or later we - can prevent this behavior by setting CMP0054 to new. For more information on - CMake policies please see the cmake-policies manpage or the `cmake-policies - online documentation - <https://cmake.org/cmake/help/v3.4/manual/cmake-policies.7.html>`_. - Lists ----- |