The implementation of the m4 black magic macro certainly looks scary. I
was able to understand the first conditional block. I did apply and try
the patch and verified that -stack-protector was added to cflags when
setting slowdebug. The readability of the macro calls are definitely
much more understandable. I like it. Looks good.
/Erik
On 2016-01-13 15:43, Magnus Ihse Bursie wrote:
Similar to how we use named argument in makefiles, we should support
named arguments in the configure scripts. This is possible using some
m4 black magic.
My long-term goal with this is to provide readable functions for
handling common patterns, like parsing --with arguments and doing
proper action depending on the value of the flag.
Since the m4 logic is hairy, to say the least, I chose to pick a more
simple function to use as test bench for getting the actual m4
underpinning to work.
The essence of this change can be seen here:
- FLAGS_COMPILER_CHECK_ARGUMENTS([$STACK_PROTECTOR_CFLAG], [],
[STACK_PROTECTOR_CFLAG=""])
+ FLAGS_COMPILER_CHECK_ARGUMENTS(ARGUMENT: [$STACK_PROTECTOR_CFLAG],
IF_FALSE: [STACK_PROTECTOR_CFLAG=""])
Just like in our Setup* macros in make, now it is possible to use
named arguments in autoconf macros. Named arguments can come in any
order. The framework will verify that only known arguments is allowed
in. It is also possible to mark an argument as compulsory (by
prefixing it with *). The framework will verify that all required
arguments are present.
Don't ask me to explain the finer points of BASIC_DEFUN_NAMED. :)
m4/autoconf is non-trivial to get correct, with few debugging
possibilities and sparse documentation. There's a lot of trial and
error behind this final version. :-&
Bug: https://bugs.openjdk.java.net/browse/JDK-8146995
WebRev:
http://cr.openjdk.java.net/~ihse/JDK-8146995-named-arguments-in-configure/webrev.01
/Magnus
