While evaluating `if(MATCHES)` we get a `const char*` pointer to the
string to be matched. On code like
if(CMAKE_MATCH_COUNT MATCHES "Y")
the string to be matched may be owned by our own result variables.
We must move the value to our own buffer before clearing them.
Otherwise we risk reading freed storage.
if(TEST TestNameThatExists) will return true if a test with the name
TestNameThatExists has been added with add_test. The syntax is similar
to if(TARGET TargetName). Since use of "TEST" as an argument to if()
could previously be interpreted as a non-keyword argument, add policy
CMP0064 to treat it as a keyword as NEW behavior.
Move failure cases from the CMake.{If,List,While,GetProperty} tests over
to the RunCMake.{if,list,while,get_property} tests to use the more
modern infrastructure. This also avoids using REGEX_ESCAPE_STRING to
try to regex-match full paths.
Add a RunCMake.if test to cover if() command behavior. Start with a
test for IS_DIRECTORY cases with an existing directory and a long path,
both with a trailing slash.
Brad King
Matt McCormick
Stephen Kelly