Import bmake-20200902vendor/NetBSD/bmake/20200902

Lots of code refactoring, simplification and cleanup.
Lots of new unit-tests providing much higher code coverage.
All courtesy of rillig at netbsd.

Other significant changes:

o new read-only variable .SHELL which provides the path of the shell
  used to run scripts (as defined by  the .SHELL target).

o new debug option -dl: LINT mode, does the equivalent of := for all
  variable assignments so that file and line number are reported for
  variable parse errors.

1 files changed, 22 insertions, 0 deletions

diff --git a/unit-tests/varmod-match.mk b/unit-tests/varmod-match.mk
new file mode 100644
index 000000000000..805426a0fda9
--- /dev/null
+++ b/unit-tests/varmod-match.mk
@@ -0,0 +1,22 @@
+# $NetBSD: varmod-match.mk,v 1.3 2020/08/16 20:03:53 rillig Exp $
+#
+# Tests for the :M variable modifier, which filters words that match the
+# given pattern.
+
+all: match-char-class
+all: slow
+
+
+NUMBERS=	One Two Three Four five six seven
+
+match-char-class:
+	@echo '$@:'
+	@echo '  uppercase numbers: ${NUMBERS:M[A-Z]*}'
+	@echo '  all the others: ${NUMBERS:M[^A-Z]*}'
+	@echo '  starts with non-s, ends with [ex]: ${NUMBERS:M[^s]*[ex]}'
+
+
+# Before 2020-06-13, this expression took quite a long time in Str_Match,
+# calling itself 601080390 times for 16 asterisks.
+slow:
+	@: ${:U****************:M****************b}