Merge bmake-20200517

Changes since 20181221 are mostly portability related
hence the large gap in versions imported.

There are however some bug fixes, and a rework of filemon handling.
In NetBSD make/filemon/filemon_ktrace.c allows use of fktrace
and elimination of filemon(4) which has not had the TLC it needs.

FreeBSD filemon(4) is in much better shape, so bmake/filemon/filemon_dev.c
allows use of that, with a bit less overhead than the ktrace model.

Summary of changes from ChangeLog

	o str.c: empty string does not match % pattern
	  plus unit-test changes
	o var.c: import handling of old sysV style modifier using '%'
	o str.c: refactor brk_string
	o meta.c: meta_oodate, CHECK_VALID_META is too aggressive for CMD
	  a blank command is perfectly valid.
	o meta.c: meta_oodate, check for corrupted meta file
	  earlier and more often.
	* meta.c: meta_compat_parent check for USE_FILEMON
	  patch from Soeren Tempel
	o meta.c: fix compat mode, need to call meta_job_output()
	o job.c: extra fds for meta mode not needed if using filemon_dev
	o meta.c: avoid passing NULL to filemon_*() when meta_needed()
	  returns FALSE.
	o filemon/filemon_{dev,ktrace}.c: allow selection of
	  filemon implementation.  filemon_dev.c uses the kernel module
	  while filemon_ktrace.c leverages the fktrace api available in
	  NetBSD.  filemon_ktrace.c can hopefully form the basis for
	  adding support for other tracing mechanisms such as strace on
	  Linux.
	o meta.c: when target is out-of-date per normal make rules
	  record value of .OODATE in meta file.
	o parse.c: don't pass NULL to realpath(3)
	  some versions cannot handle it.
	o parse.c: ParseDoDependency: free paths rather than assert

plus more unit-tests

1 files changed, 23 insertions, 0 deletions

diff --git a/contrib/bmake/unit-tests/cond-late.mk b/contrib/bmake/unit-tests/cond-late.mk
new file mode 100644
index 000000000000..2eb02b42b920
--- /dev/null
+++ b/contrib/bmake/unit-tests/cond-late.mk
@@ -0,0 +1,23 @@
+# $NetBSD: cond-late.mk,v 1.1 2020/04/29 23:15:21 rillig Exp $
+#
+# Using the :? modifier, variable expressions can contain conditional
+# expressions that are evaluated late.  Any variables appearing in these
+# conditions are expanded before parsing the condition.  This is
+# different from many other places.
+#
+# Because of this, variables that are used in these lazy conditions
+# should not contain double-quotes, or the parser will probably fail.
+#
+# They should also not contain operators like == or <, since these are
+# actually interpreted as these operators. This is demonstrated below.
+#
+# If the order of evaluation were to change to first parse the condition
+# and then expand the variables, the output would change from the
+# current "yes no" to "yes yes", since both variables are non-empty.
+
+COND.true=	"yes" == "yes"
+COND.false=	"yes" != "yes"
+
+all:
+	@echo ${ ${COND.true} :?yes:no}
+	@echo ${ ${COND.false} :?yes:no}