bug#39794: AVR-Toolchain-5 avr/io not found

[Ekaitz Zarraga]

Hi,

I've been trying to debug AVR toolchain errors found in here:

https://lists.gnu.org/archive/html/help-guix/2020-02/msg00204.html

I'm not experienced enough to know all that's going on here and I need some 
assistance to make everything work.


I'm working on QMK-Firmware (helix keyboard specifically, that is an 
Atmega32u4) has and I'm able to make it compile with avr-gcc@4.9 but when I try 
with 5 first it fails because it doesn't find `avr/io.h`.

Exporting a new CPATH variable fixes it:

`export CPATH=$CPATH:/gnu/store/.../avr/include`

Once the export is done it fails because it's unable to find `gnu/stubs-32.h` 
and I don't know which package carries that. Can you point me to it?
Should it be added to avr-gcc dependencies?

If someone has the time to help me make it work I'll make the patches and the 
tests needed, but now I don't know what else to do.

First I'd say the package for avr-gcc@5 should not inherit from avr-gcc@4.9 
because 4.9 uses CROSS_* variables and works correctly but 5 doesn't use them 
like that. So these changes solve that issue:

diff --git a/gnu/packages/avr.scm b/gnu/packages/avr.scm
index 1f99f636e0..74caec5b94 100644
--- a/gnu/packages/avr.scm
+++ b/gnu/packages/avr.scm
@@ -76,7 +76,15 @@
   (package
     (inherit avr-gcc-4.9)
     (version (package-version gcc-5))
-    (source (package-source gcc-5))))
+    (source (package-source gcc-5))
+    (native-search-paths
+      (list (search-path-specification
+              (variable "CPATH")
+              (files '("avr/include")))
+            (search-path-specification
+              (variable "LIBRARY_PATH")
+              (files '("avr/lib")))))))
+

 (define (avr-libc avr-gcc)
   (package


But I don't see how to solve the `gnu/stubs-32.h` error.
Can anyone help me a little on this?

Thanks,

ElenQ Technology
Ethical Innovation