Re: GNU Make bug report: broken dry-run functionality with sub-make invocations

[Martin Dorey]

> the statement after the pipe also gets executed

Would you have Make parse the shell command, assuming that SHELL isn't eg /usr/bin/perl, splitting off anything after | and maybe ; and && and, why not, ||, so it only dry-runs the part of the command that invoked $(MAKE)?  The current behavior is documented, https://www.gnu.org/software/make/manual/html_node/MAKE-Variable.html#MAKE-Variable saying:

>> whenever a recipe line of a rule contains the variable MAKE, the flags ‘-t’, ‘-n’ and ‘-q’ do not apply to that line

To put it another way: the Makefile needs to cope.  Not doing the tee if the directory doesn't exist would perhaps be most straightforward:

martind@sirius:~/tmp/ambrus-sumegi-2022-03-17$ diff -u Makefile{.orig,}

--- Makefile.orig 2022-03-17 11:13:46.000328340 -0700

+++ Makefile 2022-03-17 11:15:04.980482898 -0700

@@ -8,4 +8,4 @@

 

 .PHONY: main_target

 main_target: create_logdirs

- $(MAKE) external_target | tee logs/external_task.log

+ $(MAKE) external_target | { if test -d logs; then tee logs/external_task.log; else cat; fi; }

martind@sirius:~/tmp/ambrus-sumegi-2022-03-17$

... though that means writing to the log with -n if the directory does exist, which is perhaps undesirable.  You could scrape the --dry-run flag out of MAKEFLAGS, where it seems to get turned into n:

martind@sirius:~/tmp/ambrus-sumegi-2022-03-17$ diff -u Makefile{.orig,}

--- Makefile.orig 2022-03-17 11:13:46.000328340 -0700

+++ Makefile 2022-03-17 11:23:29.579910454 -0700

@@ -8,4 +8,4 @@

 

 .PHONY: main_target

 main_target: create_logdirs

- $(MAKE) external_target | tee logs/external_task.log

+ $(MAKE) external_target $(if $(findstring n,$(filter-out --%,$(MAKEFLAGS))),,| tee logs/external_task.log)

martind@sirius:~/tmp/ambrus-sumegi-2022-03-17$

That coped with -nj --no-print-directory on the one version of Make that I tested it with, but I don't know how portable that would prove.

Thank you for a nicely written up report with a minimal test case.

---

From: Bug-make <bug-make-bounces+martin.dorey=hds.com@gnu.org> on behalf of Ambrus Sumegi <Ambrus.Sumegi@arm.com>
Sent: Thursday, March 17, 2022 08:59
To: bug-make@gnu.org <bug-make@gnu.org>
Subject: GNU Make bug report: broken dry-run functionality with sub-make invocations

 

***** EXTERNAL EMAIL *****

Dear Devs,

I stumbled upon a rather rare case where Make produces a false error with the --dry-run switch. I’ve attached a sample Makefile for reproduction.

 

The output of make main_target with this file is the following:

$ make main_target

mkdir logs

make external_target | tee logs/external_task.log

make[1]: Entering directory '/tmp/21176961.tmpdir/bugrepro'

This could be in a separate file somewhere

make[1]: Leaving directory '/tmp/21176961.tmpdir/bugrepro'

 

Nothing interesting there. But with the -n or --dry-run switch I get:

$ make main_target -n

mkdir logs

make external_target | tee logs/external_task.log

tee: logs/external_task.log: No such file or directory

make[1]: Entering directory '/tmp/21176961.tmpdir/bugrepro'

echo "This could be in a separate file somewhere"

make[1]: Leaving directory '/tmp/21176961.tmpdir/bugrepro'

make: *** [Makefile:11: main_target] Error 1

 

I get that the sub-make invocation gets executed with the switch passed to it as well, and that is correct functionality. But then the statement after the pipe also gets executed and throws an error about the missing log directory due to the prerequisite target not having been run. This causes false failures in release checks that use the --dry-run option of Make.

 

This behavior is the same in both versions of GNU make that I have access to on the production system I’m using, 3.82 and 4.3

$ uname -r

3.10.0-693.21.1.el7.x86_64

$ make --version

GNU Make 3.82

Built for x86_64-redhat-linux-gnu

Copyright (C) 2010  Free Software Foundation, Inc.

License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html

This is free software: you are free to change and redistribute it.

There is NO WARRANTY, to the extent permitted by law.

# (…) Loading other version

$ make --version

GNU Make 4.3

Built for x86_64-pc-linux-gnu

Copyright (C) 1988-2020 Free Software Foundation, Inc.

License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html

This is free software: you are free to change and redistribute it.

There is NO WARRANTY, to the extent permitted by law.

IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.