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Every policy's documentation has a paragraph on what version of CMake introduced it, how to set the policy, and whether CMake warns if the policy is not set. The wording of this paragraph has diverged across policies over time. Factor the paragraph out into a standard advice document included by every policy.
29 lines
1.2 KiB
ReStructuredText
29 lines
1.2 KiB
ReStructuredText
CMP0012
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-------
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:command:`if` recognizes numbers and boolean constants.
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In CMake versions 2.6.4 and lower the :command:`if` command implicitly
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dereferenced arguments corresponding to variables, even those named
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like numbers or boolean constants, except for ``0`` and ``1``. Numbers and
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boolean constants such as ``true``, ``false``, ``yes``, ``no``, ``on``,
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``off``, ``y``, ``n``, ``notfound``, ``ignore`` (all case insensitive)
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were recognized in some cases but not all. For example, the code ``if(TRUE)``
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might have evaluated as ``false``.
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Numbers such as 2 were recognized only in boolean expressions
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like ``if(NOT 2)`` (leading to ``false``) but not as a single-argument like
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``if(2)`` (also leading to ``false``). Later versions of CMake prefer to
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treat numbers and boolean constants literally, so they should not be
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used as variable names.
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The ``OLD`` behavior for this policy is to implicitly dereference
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variables named like numbers and boolean constants. The ``NEW`` behavior
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for this policy is to recognize numbers and boolean constants without
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dereferencing variables with such names.
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.. |INTRODUCED_IN_CMAKE_VERSION| replace:: 2.8.0
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.. |WARNS_OR_DOES_NOT_WARN| replace:: warns
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.. include:: STANDARD_ADVICE.txt
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.. include:: DEPRECATED.txt
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