Sat Aug 29 16:13:27 2020 UTC ()

make(1): explain the shuffled messages in the test output


(rillig)

diff -r1.3 -r1.4 src/usr.bin/make/unit-tests/depsrc-ignore.mk

--- src/usr.bin/make/unit-tests/depsrc-ignore.mk 2020/08/29 15:06:33	1.3
+++ src/usr.bin/make/unit-tests/depsrc-ignore.mk 2020/08/29 16:13:27	1.4

 @@ -1,33 +1,67 @@
-# $NetBSD: depsrc-ignore.mk,v 1.3 2020/08/29 15:06:33 rillig Exp $
+# $NetBSD: depsrc-ignore.mk,v 1.4 2020/08/29 16:13:27 rillig Exp $
+#
 # Tests for the special source .IGNORE in dependency declarations,
 # which ignores any command failures for that target.
+#
 # Even though ignore-errors fails, the all target is still made.
 # Since the all target is not marked with .IGNORE, it stops at the
 # first failing command.
+#
-# XXX: The messages in the output are confusing.
+# XXX: The ordering of the messages in the output is confusing.
 # The "ignored" comes much too late to be related to the "false
-# ignore-errors".
+# ignore-errors".  This is due to stdout being buffered.
 # The "continuing" is confusing as well since it doesn't answer the
-# question "continuing with what?".
+# The "continuing" message comes from the -k option.  If there had been
 # other targets independent of "all", these would be built as well.
 # Even more interestingly, enabling the debugging option -de changes
-# the order in which the messages appear.  Now the "ignored" message
+# Enabling the debugging option -de changes the order in which the messages
-# is issued in the correct position.  The manual page even defines the
+# appear.  Now the "ignored" message is issued in the correct position.
-# buffering of debug_file and stdout, so there should be no variance.
+# The explanation for the output reordering is that the output is buffered.
 # As the manual page says, in debugging mode stdout is line buffered.
-#.MAKEFLAGS: -de
+# In these tests the output is redirected to a file, therefore stdout is
 # fully buffered.
+#
 # This is what actually happens, as of 2020-08-29.  To verify it, set the
 # following breakpoints in CompatRunCommand:
+#
 # * the "!silent" line, to see all commands.
 # * the "fflush" line, to see stdout being flushed.
 # * the "status = WEXITSTATUS" line
 # * the "(continuing)" line
 # * the "(ignored)" line
+#
 # The breakpoints are visited in the following order:
+#
 # "ignore-errors begin"
 #	Goes directly to STDOUT_FILENO since it is run in a child process.
 # "false ignore-errors"
 #	Goes to the stdout buffer (CompatRunCommand, keyword "!silent") and
 #	the immediate call to fflush(stdout) copies it to STDOUT_FILENO.
 # "*** Error code 1 (ignored)"
 #	Goes to the stdout buffer but is not flushed (CompatRunCommand, near
 #	the end).
 # "ignore-errors end"
 #	Goes directly to STDOUT_FILENO.
 # "all begin"
 #	Goes directly to STDOUT_FILENO.
 # "false all"
 #	Goes to the stdout buffer, where the "*** Error code 1 (ignored)" is
 #	still waiting to be flushed.  These two lines are flushed now.
 # "*** Error code 1 (continuing)"
 #	Goes to the stdout buffer.
 # "Stop."
 #	Goes to the stdout buffer.
 # exit(1)
 #	Flushes the stdout buffer to STDOUT_FILENO.
 all: ignore-errors
 ignore-errors: .IGNORE
 	@echo $@ begin
 	false $@
 	@echo $@ end
 all:
 	@echo $@ begin
 	false $@
 	@echo $@ end