CMP0174ΒΆ
New in version 3.31.
cmake_parse_arguments(PARSE_ARGV)
defines a variable for an empty
string after a single-value keyword.
One of the main reasons for using the PARSE_ARGV
form of the
cmake_parse_arguments()
command is to more robustly handle corner
cases related to empty values. The non-PARSE_ARGV
form doesn't preserve
empty arguments, but the PARSE_ARGV
form does. For each single-value
keyword given, a variable should be defined if the keyword is followed by a
value. Prior to CMake 3.31, no variable would be defined if the value given
was an empty string. This meant the code could not detect the difference
between the keyword not being given, and it being given but with an empty
value, except by iterating over all the arguments and checking if the keyword
is present.
For the OLD
behavior of this policy,
cmake_parse_arguments(PARSE_ARGV)
does not define a variable for a
single-value keyword followed by an empty string.
For the NEW
behavior, cmake_parse_arguments(PARSE_ARGV)
always
defines a variable for each keyword given in the arguments, even a single-value
keyword with an empty string as its value. With the NEW
behavior, the
code can robustly check if a single-value keyword was given with any value
using just if(DEFINED <prefix>_<keyword>)
.
This policy was introduced in CMake version 3.31.
It may be set by cmake_policy()
or cmake_minimum_required()
.
If it is not set, CMake warns, and uses OLD
behavior.
Note
The OLD
behavior of a policy is
deprecated by definition
and may be removed in a future version of CMake.