[bug#54396,v2,WIP] gnu: python-notmuch2: Fix build.

Hi Liliana,

Did you have something along these lines in mind?

I wanted to add the `create-notmuch-config` phase after the `enter-python-dir`,
but I don't know how to get the source folder from there. I suppose
there's a way to get the `../../` of the `cwd`, but I don't (yet) know how.

The generated contains the expected paths:

```
NOTMUCH_VERSION_FILE='/tmp/guix-build-python-notmuch2-0.35.drv-0/notmuch-0.35/version.txt'
NOTMUCH_INCLUDE_DIR='/tmp/guix-build-python-notmuch2-0.35.drv-0/notmuch-0.35/lib'
NOTMUCH_LIB_DIR='/tmp/guix-build-python-notmuch2-0.35.drv-0/notmuch-0.35/lib'
```

… but they **always** reference `drv-0`, even if it's not the first build!?
For instance:

```
$ cat /tmp/guix-build-python-notmuch2-0.35.drv-6/notmuch-0.35/bindings/python-cffi/_notmuch_config.py                                                                                                                      [profile] guix-dev
NOTMUCH_VERSION_FILE='/tmp/guix-build-python-notmuch2-0.35.drv-0/notmuch-0.35/version.txt'
NOTMUCH_INCLUDE_DIR='/tmp/guix-build-python-notmuch2-0.35.drv-0/notmuch-0.35/lib'
NOTMUCH_LIB_DIR='/tmp/guix-build-python-notmuch2-0.35.drv-0/notmuch-0.35/lib'
```

Does it matter?!

Regards,

--
Tanguy
---
 gnu/packages/mail.scm | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

Am Mittwoch, dem 16.03.2022 um 12:16 +0100 schrieb Tanguy Le Carrour:
> Hi Liliana,
> 
> Did you have something along these lines in mind?
> 
> I wanted to add the `create-notmuch-config` phase after the `enter-
> python-dir`,
> but I don't know how to get the source folder from there. I suppose
> there's a way to get the `../../` of the `cwd`, but I don't (yet)
> know how.
> 
> The generated contains the expected paths:
> 
> ```
> NOTMUCH_VERSION_FILE='/tmp/guix-build-python-notmuch2-0.35.drv-
> 0/notmuch-0.35/version.txt'
> NOTMUCH_INCLUDE_DIR='/tmp/guix-build-python-notmuch2-0.35.drv-
> 0/notmuch-0.35/lib'
> NOTMUCH_LIB_DIR='/tmp/guix-build-python-notmuch2-0.35.drv-0/notmuch-
> 0.35/lib'
> ```
> 
> … but they **always** reference `drv-0`, even if it's not the first
> build!?
> For instance:
> 
> ```
> $ cat /tmp/guix-build-python-notmuch2-0.35.drv-6/notmuch-
> 0.35/bindings/python-
> cffi/_notmuch_config.py                                              
>                                                                      
>    [profile] guix-dev
> NOTMUCH_VERSION_FILE='/tmp/guix-build-python-notmuch2-0.35.drv-
> 0/notmuch-0.35/version.txt'
> NOTMUCH_INCLUDE_DIR='/tmp/guix-build-python-notmuch2-0.35.drv-
> 0/notmuch-0.35/lib'
> NOTMUCH_LIB_DIR='/tmp/guix-build-python-notmuch2-0.35.drv-0/notmuch-
> 0.35/lib'
> ```
> 
> Does it matter?!
Yes, it does matter.  The cwd you reference will no longer exist when
the bindings are installed.  The purpose of generating the file is to
fill it with useful, persisting data, i.e. (dirname (search-input-file
inputs "notmuch.h")) and (dirname (search-input-file inputs
"libnotmuch.so")).  As for the version file, that should probably be
set to an error value such as None or NotImplemented or even unset.  It
does not appear to be currently used and we don't install any such file
for notmuch.

Cheers

Hi Liliana,


Quoting Liliana Marie Prikler (2022-03-16 12:28:49)
> Am Mittwoch, dem 16.03.2022 um 12:16 +0100 schrieb Tanguy Le Carrour:
> > The generated contains the expected paths:
> > […]
> > 
> > … but they **always** reference `drv-0`, even if it's not the first
> > build!?
> > For instance:
> > 
> > ```
> > $ cat /tmp/guix-build-python-notmuch2-0.35.drv-6/notmuch-
> > 0.35/bindings/python-
> > cffi/_notmuch_config.py
> > NOTMUCH_VERSION_FILE='/tmp/guix-build-python-notmuch2-0.35.drv-
> > 0/notmuch-0.35/version.txt'
> > NOTMUCH_INCLUDE_DIR='/tmp/guix-build-python-notmuch2-0.35.drv-
> > 0/notmuch-0.35/lib'
> > NOTMUCH_LIB_DIR='/tmp/guix-build-python-notmuch2-0.35.drv-0/notmuch-
> > 0.35/lib'
> > ```
> > 
> > Does it matter?!
> Yes, it does matter.  The cwd you reference will no longer exist when
> the bindings are installed.  The purpose of generating the file is to
> fill it with useful, persisting data,

Oh, I thought it was only used at build time! Sorry, my mistake!


> i.e. (dirname (search-input-file inputs "notmuch.h")) and
> (dirname (search-input-file inputs "libnotmuch.so")).

Unfortunately, I couldn't make those work. :-(

So I ended up with a less "sexy" version:

```
"NOTMUCH_INCLUDE_DIR='" (assoc-ref inputs "notmuch") "/include/notmuch.h" "'\n"
"NOTMUCH_LIB_DIR='" (assoc-ref inputs "notmuch") "/lib/libnotmuch.so" "'"
```


> As for the version file, that should probably be
> set to an error value such as None or NotImplemented or even unset.  It
> does not appear to be currently used and we don't install any such file
> for notmuch.

If I set `NOTMUCH_VERSION_FILE=''`, I get a "file does not exist" error
at build time. So I decided to set it to `/dev/null` instead. Or would
it be better if I patched `notmuch` to create the actual version file?!

Thanks again for your precious help!

Hi,

Am Mittwoch, dem 16.03.2022 um 14:46 +0100 schrieb Tanguy LE CARROUR:
> Hi Liliana,
> [...]
> 
> > i.e. (dirname (search-input-file inputs "notmuch.h")) and
> > (dirname (search-input-file inputs "libnotmuch.so")).
> 
> Unfortunately, I couldn't make those work. :-(
> 
> So I ended up with a less "sexy" version:
> 
> ```
> "NOTMUCH_INCLUDE_DIR='" (assoc-ref inputs "notmuch")
> "/include/notmuch.h" "'\n"
> "NOTMUCH_LIB_DIR='" (assoc-ref inputs "notmuch") "/lib/libnotmuch.so"
> "'"
> ```
That is actually a mistake on my part, search-input-file should search
inputs for "include/notmuch.h" and likewise "lib/libnotmuch.so".  The
dirname is important here, since both constants want directories. 
Alternatively, forgoing those constants might be a good idea, but is
not worth investing too much time in.

> > As for the version file, that should probably be set to an error
> > value such as None or NotImplemented or even unset.  It does not
> > appear to be currently used and we don't install any such file
> > for notmuch.
> 
> If I set `NOTMUCH_VERSION_FILE=''`, I get a "file does not exist"
> error at build time. So I decided to set it to `/dev/null` instead.
> Or would it be better if I patched `notmuch` to create the actual
> version file?!
I think you ought to debug the build and short-circuit the logic by
inferring the version number directly where it is needed.  Without
actual build output that's as much as I can propose.

Cheers