mirror/CMake
1
0
Fork 0
mirror of https://github.com/Kitware/CMake.git synced 2026-02-26 18:58:34 -06:00
Code Issues Packages Projects Releases Wiki Activity

Merge topic 'doc-if-basic-expressions'

Browse Source 
294581a443 Help: Be more explicit about the behavior of if(<string>)
3a9695557d Help: Explicitly state that if(ENV{some_var}) is always false

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !6768
This commit is contained in:
Brad King
2021-12-01 14:37:20 +00:00
committed by Kitware Robot
parent 1e0b4b5f39 294581a443
commit 1c77801636
1 changed files with 15 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
Help/command/if.rst
View File

@@ -56,12 +56,23 @@ Basic Expressions
``NO``, ``FALSE``, ``N``, ``IGNORE``, ``NOTFOUND``, the empty string,
or ends in the suffix ``-NOTFOUND``. Named boolean constants are
case-insensitive. If the argument is not one of these specific
constants, it is treated as a variable or string and the following
signature is used.
constants, it is treated as a variable or string (see `Variable Expansion`_
further below) and one of the following two forms applies.
``if(<variable|string>)``
``if(<variable>)``
True if given a variable that is defined to a value that is not a false
constant. False otherwise. (Note macro arguments are not variables.)
constant. False otherwise, including if the variable is undefined.
Note that macro arguments are not variables.
Environment variables also cannot be tested this way, e.g.
``if(ENV{some_var})`` will always evaluate to false.
``if(<string>)``
A quoted string always evaluates to false unless:
* The string's value is one of the true constants, or
* Policy :policy:`CMP0054` is not set to ``NEW`` and the string's value
happens to be a variable name that is affected by :policy:`CMP0054`'s
behavior.
Logic Operators
"""""""""""""""