[SV 13862] Implement the .WAIT special target

The next version of the POSIX standard defines parallel execution
and requires the .WAIT special target as is implemented in some other
versions of make.

This implementation behaves similarly to others in that it does not
create a relationship between targets in the dependency graph, so
that the same two targets may be run in parallel if they appear as
prerequisites elsewhere without .WAIT between them.

Now that we support .WAIT it's trivial to also support prerequisites
of the .NOTPARALLEL special target, which forces the prerequisites of
those targets to be run serially (as if .WAIT was specified between
each one).

* NEWS: Announce the new .WAIT and .NOTPARALLEL support.
* doc/make.texi (Parallel Disable): A new section to discuss ways in
which parallel execution can be controlled.  Modify cross-refs to
refer to this section.
* src/dep.h (struct dep): Add a new wait_here boolean.
(parse_file_seq): Add PARSEFS_WAIT to check for .WAIT dependencies.
* src/file.c (split_prereqs): Use PARSEFS_WAIT.
(snap_deps): If .NOTPARALLEL has prerequisites, set .WAIT between
each of _their_ prerequisites.
(print_prereqs): Add back in .WAIT when printing prerequisites.
* src/implicit.c (struct patdeps): Preserve wait_here.
(pattern_search): Ditto.  Use PARSEFS_WAIT when parsing prereqs for
pattern rule expansion.
* src/read.c (check_specials): Don't give up early: remembering to
update these options is not worth the rare speedup.
(check_special_file): If .WAIT is given as a target show an error--
once--if it has prereqs or commands.
(record_files): Call check_special_file on each target.
(parse_file_seq): If PARSEFS_WAIT is given, look for .WAIT prereqs.
If we see one assume that we are building a struct dep chain and set
the wait_here option while not putting it into the list.
* src/remake.c (update_file_1): If wait_here is set and we are still
running, then stop trying to build this target's prerequisites.
* src/rule.c (get_rule_defn): Add .WAIT to the prerequisite list.
* src/shuffle.c (shuffle_deps): Don't shuffle the prerequisite list
if .WAIT appears anywhere in it.
* tests/scripts/targets/WAIT: Add a test suite for this feature.

1 files changed, 193 insertions, 0 deletions

diff --git a/tests/scripts/targets/WAIT b/tests/scripts/targets/WAIT
new file mode 100644
index 00000000..24cf9179
--- /dev/null
+++ b/tests/scripts/targets/WAIT
@@ -0,0 +1,193 @@
+#                                                                    -*-perl-*-
+
+$description = "Test the behaviour of the .WAIT target.";
+
+$details = "";
+
+# Ensure .WAIT doesn't appear in any automatic variables
+
+run_make_test(q!
+all: .WAIT pre1 .WAIT pre2 | .WAIT pre3 ; @echo '<=$< ^=$^ ?=$? +=$+ |=$|'
+pre1 pre2 pre3:;
+
+# This is just here so we don't fail with older versions of make
+.WAIT:
+!,
+    '', '<=pre1 ^=pre1 pre2 ?=pre1 pre2 +=pre1 pre2 |=pre3');
+
+run_make_test(q!
+.SECONDEXPANSION:
+all: $$(pre) ; @echo '<=$< ^=$^ ?=$? +=$+ |=$|'
+pre1 pre2 pre3:;
+
+pre = .WAIT pre1 .WAIT pre2 | .WAIT pre3
+# This is just here so we don't fail with older versions of make
+.WAIT:
+!,
+    '', '<=pre1 ^=pre1 pre2 ?=pre1 pre2 +=pre1 pre2 |=pre3');
+
+run_make_test(q!
+all: pre
+p% : .WAIT p%1 .WAIT p%2 | .WAIT p%3; @echo '<=$< ^=$^ ?=$? +=$+ |=$|'
+pre1 pre2 pre3: ;
+
+# This is just here so we don't fail with older versions of make
+.WAIT:
+!,
+              '', "<=pre1 ^=pre1 pre2 ?=pre1 pre2 +=pre1 pre2 |=pre3\n");
+
+# Unfortunately I don't think we can get away from using sleep here; at least
+# I can't think of any way to make sure .WAIT works without it.  Even with it,
+# it's not reliable (in that even if .WAIT is not working we MIGHT succeed the
+# test--it shouldn't ever be the case that we fail the test unexpectedly).
+# That makes this test suite slow to run :-/.
+
+run_make_test(q!
+all : pre1 .WAIT pre2
+pre1: ; @#HELPER# -q out start-$@ sleep 1 out end-$@
+pre2: ; @#HELPER# -q out $@
+
+# This is just here so we don't fail with older versions of make
+.WAIT:
+!,
+              '-j10', "start-pre1\nend-pre1\npre2\n");
+
+# Ensure .WAIT doesn't add extra a dependency between its targets
+
+run_make_test(undef, '-j10 pre2', "pre2\n");
+
+# Ensure .WAIT doesn't wait between all targets
+
+run_make_test(q!
+all : pre1 .WAIT pre2 pre3
+pre1: ; @#HELPER# -q out start-$@ sleep 1 out end-$@
+pre2: ; @#HELPER# -q out start-$@ file TWO wait THREE out end-$@
+pre3: ; @#HELPER# -q wait TWO out $@ file THREE
+
+# This is just here so we don't fail with older versions of make
+.WAIT:
+!,
+              '-j10', "start-pre1\nend-pre1\nstart-pre2\npre3\nend-pre2\n");
+
+unlink(qw(TWO THREE));
+
+# Ensure .WAIT waits for ALL targets on the left before ANY targets on the right
+
+run_make_test(q!
+all : pre1 pre2 .WAIT post1 post2
+pre1: ; @#HELPER# -q out start-$@ file PRE1 wait PRE2 sleep 1 out end-$@
+pre2: ; @#HELPER# -q wait PRE1 out $@ file PRE2
+
+post1: ; @#HELPER# -q wait POST2 out $@ file POST1
+post2: ; @#HELPER# -q file POST2 wait POST1 out $@
+
+# This is just here so we don't fail with older versions of make
+.WAIT:
+!,
+              '-j10', "start-pre1\npre2\nend-pre1\npost1\npost2\n");
+
+unlink(qw(PRE1 PRE2 POST1 POST2));
+
+# See if .WAIT takes effect between different lists of prereqs
+# In the current implementation, .WAIT waits only between two prerequisites
+# in a given target.  These same two targets might be run in a different
+# order if they appear as prerequisites of another target.  This is the way
+# other implementations of .WAIT work.  I personally think it's gross and
+# makes .WAIT just a toy when it comes to ordering, but it's much simpler
+# to implement than creating an actual edge in the DAG to represent .WAIT
+# and since that's what users expect, we'll do the same for now.
+
+run_make_test(q!
+all : one two
+one: pre1 .WAIT pre2
+two: pre2 pre1
+pre1: ; @#HELPER# -q out start-$@ sleep 1 out end-$@
+pre2: ; @#HELPER# -q out $@
+
+# This is just here so we don't fail with older versions of make
+.WAIT:
+!,
+              '-j10', "start-pre1\npre2\nend-pre1\n");
+
+# Check that .WAIT works with pattern rules
+
+run_make_test(q!
+all: pre
+p% : p%1 .WAIT p%2;
+pre1: ; @#HELPER# -q out start-$@ sleep 1 out end-$@
+pre2: ; @#HELPER# -q out $@
+
+# This is just here so we don't fail with older versions of make
+.WAIT:
+!,
+              '-j10', "start-pre1\nend-pre1\npre2\n");
+
+# Check that .WAIT works with secondarily expanded rules
+
+run_make_test(q!
+.SECONDEXPANSION:
+all: $$(pre)
+pre1: ; @#HELPER# -q out start-$@ sleep 1 out end-$@
+pre2: ; @#HELPER# -q out $@
+pre3: ; @#HELPER# -q out $@
+
+pre = .WAIT pre1 .WAIT pre2 | .WAIT pre3
+
+# This is just here so we don't fail with older versions of make
+.WAIT:
+!,
+              '-j10', "start-pre1\nend-pre1\npre2\npre3\n");
+
+# Verify NOTPARALLEL works
+
+run_make_test(q!
+all : pre1 pre2
+pre1: ; @#HELPER# -q out start-$@ sleep 1 out end-$@
+pre2: ; @#HELPER# -q out $@
+
+.NOTPARALLEL:
+!,
+              '-j10', "start-pre1\nend-pre1\npre2\n");
+
+run_make_test(q!
+all : p1 .WAIT np1
+
+p1: pre1 pre2
+pre1: ; @#HELPER# -q out start-$@ sleep 1 out end-$@
+pre2: ; @#HELPER# -q out $@
+
+np1: npre1 npre2
+npre1: ; @#HELPER# -q out start-$@ sleep 1 out end-$@
+npre2: ; @#HELPER# -q out $@
+
+.NOTPARALLEL: np1
+!,
+              '-j10', "start-pre1\npre2\nend-pre1\nstart-npre1\nend-npre1\nnpre2\n");
+
+# Ensure we don't shuffle if .WAIT is set
+
+run_make_test(q!
+all : pre1 .WAIT pre2
+pre1: ; @#HELPER# -q out start-$@ sleep 1 out end-$@
+pre2: ; @#HELPER# -q out $@
+
+# This is just here so we don't fail with older versions of make
+.WAIT:
+!,
+              '-j10 --shuffle=reverse', "start-pre1\nend-pre1\npre2\n");
+
+# Warn about invalid .WAIT definitions
+
+run_make_test(q!
+.WAIT: foo
+.WAIT: ; echo oops
+all:;@:
+!,
+              '', "#MAKEFILE#:2: .WAIT should not have prerequisites\n#MAKEFILE#:3: .WAIT should not have commands\n");
+
+# This tells the test driver that the perl test script executed properly.
+1;
+
+### Local Variables:
+### eval: (setq whitespace-action (delq 'auto-cleanup whitespace-action))
+### End: