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

[Ambrus Sumegi]

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.

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