Fix problems with losing tokens in the jobserver, reported by Grant

Taylor.  There are two forms of this: first, it was possible to lose
tokens when using -j and -l at the same time, because waiting jobs were
not checked when determining whether any jobs were outstanding.  Second,
if you had an exported recursive variable that contained a $(shell ...)
function there is a possibility to lose tokens, since a token was taken
but the child list was not updated until after the shell function was
complete.

To resolve this I introduced a new variable that counted the number of
tokens we have obtained, rather than checking whether there were any
children on the list.  I also added some sanity checks to make sure we
weren't writing back too many or not enough tokens.  And, the master
make will drain the token pipe before exiting and compare the count of
tokens at the end to what was written there at the beginning.

Also:
  * Ensure a bug in the environment (missing "=") doesn't cause make to core.
  * Rename the .DEFAULT_TARGET variable to .DEFAULT_GOAL, to match the
    terminology in the documentation and other variables like MAKECMDGOALS.
  * Add documentation of the .DEFAULT_GOAL special variable.

Still need to document the secondary expansion stuff...

2 files changed, 40 insertions, 61 deletions

diff --git a/tests/scripts/features/parallelism b/tests/scripts/features/parallelism
index f500352..4768539 100644
--- a/tests/scripts/features/parallelism
+++ b/tests/scripts/features/parallelism
@@ -26,58 +26,32 @@ else {
   $sleep_command = "sleep";
 }
 
-open(MAKEFILE,"> $makefile");
 
-print MAKEFILE <<"EOF";
+run_make_test("
 all : def_1 def_2 def_3
 def_1 : ; \@echo ONE; $sleep_command 3 ; echo TWO
 def_2 : ; \@$sleep_command 2 ; echo THREE
-def_3 : ; \@$sleep_command 1 ; echo FOUR
-EOF
-
-close(MAKEFILE);
-
-&run_make_with_options($makefile, "-j 4", &get_logfile);
-$answer = "ONE\nFOUR\nTHREE\nTWO\n";
-&compare_output($answer, &get_logfile(1));
-
+def_3 : ; \@$sleep_command 1 ; echo FOUR",
+              '-j4', "ONE\nFOUR\nTHREE\nTWO");
 
 # Test parallelism with included files.  Here we sleep/echo while
 # building the included files, to test that they are being built in
 # parallel.
-
-$makefile2 = &get_tmpfile;
-
-open(MAKEFILE,"> $makefile2");
-
-print MAKEFILE <<"EOF";
+run_make_test("
 all: 1 2; \@echo success
-
 -include 1.inc 2.inc
-
-1.inc: ; \@echo ONE.inc; $sleep_command 2; echo TWO.inc; echo "1: ; \@echo ONE; $sleep_command 2; echo TWO" > \$\@
-2.inc: ; \@$sleep_command 1; echo THREE.inc; echo "2: ; \@$sleep_command 1; echo THREE" > \$\@
-EOF
-
-close(MAKEFILE);
-
-&run_make_with_options("$makefile2", "-j 4", &get_logfile);
-$answer = "ONE.inc\nTHREE.inc\nTWO.inc\nONE\nTHREE\nTWO\nsuccess\n";
-&compare_output($answer, &get_logfile(1));
+1.inc: ; \@echo ONE.inc; $sleep_command 2; echo TWO.inc; echo '1: ; \@echo ONE; $sleep_command 2; echo TWO' > \$\@
+2.inc: ; \@$sleep_command 1; echo THREE.inc; echo '2: ; \@$sleep_command 1; echo THREE' > \$\@",
+              "-j4",
+              "ONE.inc\nTHREE.inc\nTWO.inc\nONE\nTHREE\nTWO\nsuccess\n");
 
 unlink('1.inc', '2.inc');
 
 
 # Test parallelism with included files--this time recurse first and make
 # sure the jobserver works.
-
-$makefile3 = &get_tmpfile;
-
-open(MAKEFILE,"> $makefile3");
-
-print MAKEFILE <<"EOF";
-recurse: ; \@\$(MAKE) --no-print-directory -f $makefile3 INC=yes all
-
+run_make_test("
+recurse: ; \@\$(MAKE) --no-print-directory -f #MAKEFILE# INC=yes all
 all: 1 2; \@echo success
 
 INC = no
@@ -85,23 +59,28 @@ ifeq (\$(INC),yes)
 -include 1.inc 2.inc
 endif
 
-1.inc: ; \@echo ONE.inc; $sleep_command 2; echo TWO.inc; echo "1: ; \@echo ONE; $sleep_command 2; echo TWO" > \$\@
-2.inc: ; \@$sleep_command 1; echo THREE.inc; echo "2: ; \@$sleep_command 1; echo THREE" > \$\@
-EOF
+1.inc: ; \@echo ONE.inc; $sleep_command 2; echo TWO.inc; echo '1: ; \@echo ONE; $sleep_command 2; echo TWO' > \$\@
+2.inc: ; \@$sleep_command 1; echo THREE.inc; echo '2: ; \@$sleep_command 1; echo THREE' > \$\@",
+              "-j4",
+              "ONE.inc\nTHREE.inc\nTWO.inc\nONE\nTHREE\nTWO\nsuccess\n");
 
-close(MAKEFILE);
+unlink('1.inc', '2.inc');
 
-&run_make_with_options("$makefile3", "-j 4", &get_logfile);
-$answer = "ONE.inc\nTHREE.inc\nTWO.inc\nONE\nTHREE\nTWO\nsuccess\n";
-&compare_output($answer, &get_logfile(1));
+# Grant Taylor reports a problem where tokens can be lost (not written back
+# to the pipe when they should be): this happened when there is a $(shell ...)
+# function in an exported recursive variable.  I added some code to check
+# for this situation and print a message if it occurred.  This test used
+# to trigger this code when I added it but no longer does after the fix.
 
-unlink('1.inc', '2.inc');
+run_make_test("
+export HI = \$(shell \$(\$\@.CMD))
+first.CMD = echo hi
+second.CMD = $sleep_command 4; echo hi
 
-# Test shell functions within commands: make sure they're not reducing our
-# parallelism.
+.PHONY: all first second
+all: first second
 
-run_make_test('.PHONY: all
-all: ; @echo $(shell echo hi)
-','','hi');
+first second: ; \@echo \$\@; $sleep_command 1; echo \$\@",
+              '-j2', "first\nfirst\nsecond\nsecond");
 
 1;
diff --git a/tests/scripts/variables/DEFAULT_TARGET b/tests/scripts/variables/DEFAULT_GOAL
index d8f1173..897bd4a 100644
--- a/tests/scripts/variables/DEFAULT_TARGET
+++ b/tests/scripts/variables/DEFAULT_GOAL
@@ -1,5 +1,5 @@
 #                                                                    -*-perl-*-
-$description = "Test the .DEFAULT_TARGET special variable.";
+$description = "Test the .DEFAULT_GOAL special variable.";
 
 $details = "";
 
@@ -11,24 +11,24 @@ run_make_test('
 #
 foo: ; @:
 
-ifneq ($(.DEFAULT_TARGET),foo)
+ifneq ($(.DEFAULT_GOAL),foo)
 $(error )
 endif
 
 # Reset to empty.
 #
-.DEFAULT_TARGET :=
+.DEFAULT_GOAL :=
 
 bar: ; @:
 
-ifneq ($(.DEFAULT_TARGET),bar)
+ifneq ($(.DEFAULT_GOAL),bar)
 $(error )
 endif
 
-# Change to a different target.
+# Change to a different goal.
 #
 
-.DEFAULT_TARGET := baz
+.DEFAULT_GOAL := baz
 
 baz: ; @echo $@
 ',
@@ -36,23 +36,23 @@ baz: ; @echo $@
 'baz');
 
 
-# Test #2: unknown target.
+# Test #2: unknown goal.
 #
 run_make_test('
-.DEFAULT_TARGET := foo
+.DEFAULT_GOAL = foo
 ',
 '',
-'make: *** No rule to make target `foo\'.  Stop.',
+'#MAKE#: *** No rule to make target `foo\'.  Stop.',
 512);
 
 
-# Test #3: more than one target.
+# Test #3: more than one goal.
 #
 run_make_test('
-.DEFAULT_TARGET := foo bar
+.DEFAULT_GOAL := foo bar
 ',
 '',
-'make: *** .DEFAULT_TARGET contains more than one target.  Stop.',
+'#MAKE#: *** .DEFAULT_GOAL contains more than one target.  Stop.',
 512);