[bug #51267] Improve error handling after a special command

[Markus Elfring]

URL:
<http://savannah.gnu.org/bugs/?51267>

Summary: Improve error handling after a special command
Project: make
Submitted by: elfring
Submitted on: Mon 19 Jun 2017 06:08:34 PM CEST
Severity: 3 - Normal
Item Group: Bug
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Component Version: 4.2.1
Operating System: Any
Fixed Release: None
Triage Status: None

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Details:

I have noticed the following code fragment in a recipe which is mentioned in
the section “Generating prerequisites automatically” of the
documentation.
https://www.gnu.org/software/make/manual/html_node/Automatic-Prerequisites.html#index-make-depend

…
$(CC) -M $(CPPFLAGS) $< > $@.$$$$; \
…

The semicolon indicates at the end that the return value is ignored there. I
imagine that further data processing should usually only be performed if this
command succeeded.
Would you like to improve the exception handling for such a situation?




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[Henrik Carlqvist]

On Mon, 19 Jun 2017 12:08:35 -0400 (EDT)

Post by Markus Elfring
The semicolon indicates at the end that the return value is ignored
there. I imagine that further data processing should usually only be
performed if this command succeeded.
Would you like to improve the exception handling for such a situation?

If you really think that is a bug you should file that bug to the writers
of the shell. Make calls commands in a shell and the result is as in the
shell.

Try the following at your shell prompt:

true && echo everything is fine
echo $?
false && echo evertyhing is fine
echo $?
false ; echo everything is fine
echo $?

regards Henrik

[Paul Smith]

Post by Henrik Carlqvist
On Mon, 19 Jun 2017 12:08:35 -0400 (EDT)

Post by Markus Elfring
The semicolon indicates at the end that the return value is ignored
there. I imagine that further data processing should usually only
be performed if this command succeeded.
Would you like to improve the exception handling for such a
situation?

If you really think that is a bug you should file that bug to the
writers of the shell. Make calls commands in a shell and the result
is as in the shell.

I think Markus is suggesting that the example in the documentation be
improved to not have this problem regarding losing the return value.

That's probably a good idea, although this entire method of managing
automatically generated dependencies is essentially obsolete. Arguably this entire section should be rewritten from scratch to use more modern methods.

[Paul D. Smith]

Update of bug #51267 (project make):

Item Group: Bug => Documentation


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[Paul D. Smith]

Update of bug #51267 (project make):

Status: None => Not A Bug
Open/Closed: Open => Closed

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Follow-up Comment #1:

The very first line in the recipe command in that example is:


set -e; ...


This means that any command that fails in the recipe command immediately exits
that command with an error. There is no need to check every command
individually for errors.

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