James Bigler wrote:
I also agree that trying to maintain backwards compatibility to the
detriment of the future can become a hinderance. I just had a collegue
who was extreemly frustrated for several hours with why his build didn't
work, only to discover that he should have been using ADD_SUBDIRECTORIES
instead of SUBDIRS. There was no warning from CMake stating that he
shouldn't be using it (I would argue that CMake should warn about the
use of SUBDIRS).
That would be lots of warnings! SUBDIRS was the only way to do things
for a long time. CMake itself still uses them so it can be bootstrapped
with older versions of CMake. SUBDIRS still works, it just works
different. The behavior of both are documented.
Aside from the backwards compatibility issue, this cmake code should
work, but it produces a FATAL_ERROR:
SET(CMAKE_ALLOW_LOOSE_LOOP_CONSTRUCTS TRUE)
SET(A TRUE)
SET(B FALSE)
IF(A EQUAL B)
MESSAGE(FATAL_ERROR "${A} shouldn't equal ${B}")
ELSE()
MESSAGE("${A} should equal ${B}")
ENDIF()
SET(B 1)
IF(A EQUAL B)
MESSAGE("${A} should equal ${B}")
ELSE()
MESSAGE(FATAL_ERROR "${A} shouldn't equal ${B}")
ENDIF()
Why should TRUE EQUAL 1?
From the docs of IF:
IF(variable LESS number)
IF(string LESS number)
IF(variable GREATER number)
IF(string GREATER number)
IF(variable EQUAL number)
IF(string EQUAL number)
True if the given string or variable's value is a valid number and the
inequality or equality is true.
TRUE is not a valid number, EQUAL only works on numbers.
-Bill
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