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55 lines
1.4 KiB
ReStructuredText
55 lines
1.4 KiB
ReStructuredText
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CMP0054
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-------
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.. versionadded:: 3.1
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Only interpret :command:`if` arguments as variables or keywords when unquoted.
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CMake 3.1 and above no longer implicitly dereference variables or
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interpret keywords in an :command:`if` command argument when
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it is a :ref:`Quoted Argument` or a :ref:`Bracket Argument`.
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The ``OLD`` behavior for this policy is to dereference variables and
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interpret keywords even if they are quoted or bracketed.
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The ``NEW`` behavior is to not dereference variables or interpret keywords
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that have been quoted or bracketed.
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Given the following partial example:
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::
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set(A E)
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set(E "")
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if("${A}" STREQUAL "")
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message("Result is TRUE before CMake 3.1 or when CMP0054 is OLD")
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else()
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message("Result is FALSE in CMake 3.1 and above if CMP0054 is NEW")
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endif()
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After explicit expansion of variables this gives:
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::
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if("E" STREQUAL "")
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With the policy set to ``OLD`` implicit expansion reduces this semantically to:
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::
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if("" STREQUAL "")
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With the policy set to ``NEW`` the quoted arguments will not be
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further dereferenced:
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::
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if("E" STREQUAL "")
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This policy was introduced in CMake version 3.1.
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CMake version |release| warns when the policy is not set and uses
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``OLD`` behavior. Use the :command:`cmake_policy` command to set
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it to ``OLD`` or ``NEW`` explicitly.
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.. include:: DEPRECATED.txt
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