Remove use of an old hack that takes advantage of the auto-dereference
behavior of the if() command to detect if a variable is defined. The
hack has the form:
if("${VAR} MATCHES "^${VAR}$")
where "${VAR}" is a macro argument reference. Use if(DEFINED) instead.
This also avoids warnings for CMake Policy CMP0054 in CMake 3.1.
Revert commit 2257deb502 (Cmake: Avoid cycle directory dependencies,
2014-08-22) and add a comment explaining the purpose of the original
code.
The check_library_exists_concat macro is intended to be called multiple
times on a sequence of possibly dependent libraries. Later libraries
may depend on earlier libraries when they are static. They cannot be
safely linked in reverse order on some platforms.
Signed-off-by: Brad King <brad.king@kitware.com>
Revert commit 1269df2e3b (Cmake: Don't check for all headers each
time, 2014-08-15) and add a comment explaining the purpose of the
original code.
The check_include_file_concat macro is intended to be called multiple
times on a sequence of possibly dependent headers. Later headers
may depend on earlier headers to provide declarations. They cannot
be safely included independently on some platforms.
For example, many POSIX APIs document including sys/types.h before some
other headers. Also on some OS X versions sys/socket.h must be included
before net/if.h or the check for the latter will fail.
Signed-off-by: Brad King <brad.king@kitware.com>
Because we prepended libraries to list, CMake had troubles resolving
link directory order as it detected some cycles. Appending to list ensures
that dependencies will preceed dependees.
One header at a time is the right way. Apart from that the output on
windows goes from:
...
-- Looking for include files I:/src/libssh2-1.4.3/include/libssh2.h, ws2tcpip.h
-- Looking for include files I:/src/libssh2-1.4.3/include/libssh2.h, ws2tcpip.h
- found
-- Looking for 3 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., wins
ock2.h
-- Looking for 3 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., wins
ock2.h - found
-- Looking for 4 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., stdi
o.h
-- Looking for 4 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., stdi
o.h - found
-- Looking for 5 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., wind
ows.h
-- Looking for 5 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., wind
ows.h - found
-- Looking for 6 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., wins
ock.h
-- Looking for 6 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., wins
ock.h - found
-- Looking for 7 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., sys/
filio.h
-- Looking for 7 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., sys/
filio.h - not found
-- Looking for 7 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., sys/
ioctl.h
-- Looking for 7 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., sys/
ioctl.h - not found
-- Looking for 7 include files I:/src/libssh2-1.4.3/include/libssh2.h, ..., sys/
resource.h
...
To much nicer:
...
-- Looking for ws2tcpip.h
-- Looking for ws2tcpip.h - found
-- Looking for winsock2.h
-- Looking for winsock2.h - found
-- Looking for stdio.h
-- Looking for stdio.h - found
-- Looking for windows.h
-- Looking for windows.h - found
-- Looking for winsock.h
-- Looking for winsock.h - found
-- Looking for sys/filio.h
-- Looking for sys/filio.h - not found
-- Looking for sys/ioctl.h
-- Looking for sys/ioctl.h - not found
-- Looking for sys/resource.h
