Re: GNU make troubleshooting

[Alejandro Colomar]

Hi Paul,

On 2023-08-26 18:48, Paul Smith wrote:
> I added a new appendix to the GNU make manual for troubleshooting help;
> I haven't pushed it yet.  See below.  Comments welcome.
> 
> I think the outline you provided earlier, Bruno, has the problem that a
> lot of it isn't really about troubleshooting per se, it's about how to
> write makefiles in general.  I tried to restrict this specifically to
> describing the types of problems you might see and the steps you might
> take to troubleshoot them.
> 
> I'm thinking of adding another chapter on hints and tips for writing
> good makefiles.
> 
> -----------------
> Appendix C Troubleshooting Make and Makefiles
> *********************************************
> 
> Troubleshooting 'make' and makefiles can be tricky.  There are two
> reasons: first, makefiles are not procedural programs and many users are
> used to procedural languages and scripts.  Second, makefiles consist of
> two different syntaxes in one file: makefile syntax, that 'make' reads,
> and shell syntax, which is sent to a shell program for parsing and
> execution.
> 
>    If you have problems with GNU Make, first consider the type of
> problem you are having.  Problems will generally be in one of these
> categories:
> 
>    * A syntax or other error was reported when 'make' attempted to parse
>      your makefiles.
> 
>    * A command that 'make' invoked failed (exited with a non-0 exit
>      code).
> 
>    * The command that 'make' invoked was not the one you expected.
> 
>    * 'make' was not able to find a rule to build a target.
> 
>    * 'make' rebuilds a target that you didn't think was out of date.
> 
>    * Or, 'make' did not rebuild a target that you expected it to build.

Let's add one more:

-  Make has problems running the SHELL


```
$ cat Makefile 
SHELL := /usr/bin/env -S bash -Eeuo pipefail
foo:
        $(info FOO)
        echo foo

$ make
FOO
echo foo
foo
```


All good so far.  Let's try .ONESHELL:


```
$ cat Makefile 
SHELL := /usr/bin/env -S bash -Eeuo pipefail
foo:
        $(info FOO)
        echo foo
.ONESHELL:

$ make
FOO

echo foo
make: /usr/bin/env -S bash -Eeuo pipefail: No such file or directory
make: *** [Makefile:3: foo] Error 127
```


Kaboom.  :(
Okay, I know I should be using .SHELLFLAGS.  Let's see.


```
$ cat Makefile 
SHELL := /usr/bin/env
.SHELLFLAGS := -S bash -Eeuo pipefail
foo:
        $(info FOO)
        echo foo
.ONESHELL:

$ make
FOO

echo foo
bash: 
echo foo: No such file or directory
make: *** [Makefile:4: foo] Error 1
```


Ain't good either.  At least now it's a 1.
Anyway, let's try without .ONESHELL:


```
$ cat Makefile 
SHELL := /usr/bin/env
.SHELLFLAGS := -S bash -Eeuo pipefail
foo:
        $(info FOO)
        echo foo

$ make
FOO
echo foo
bash: echo foo: No such file or directory
make: *** [Makefile:5: foo] Error 1
```


Still kaboom.

In the end, I found that the problem is that you don't pipe the
scripts to the shell, but rather pass them as an argument, isn't it?
I'm not sure why this became a problem to me only when starting
to use .ONESHELL, though.


Cheers,
Alex

-- 
<http://www.alejandro-colomar.es/>
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