[bug#70202] [PATCH] doc: Add message for common error about make check-system

[Richard Sent]

* doc/guix.texi: Mention that make clean may need to be run before running
make check-system when previous builds were run with different work trees. See
https://issues.guix.gnu.org/47573.

Change-Id: I39d465961637d9fc6b11f59e1500770220780b4c
---
Hi Guix!

Ran into this issue myself. It seems common enough to be worth
mentioning in the docs, similar to the message in (guix) Building from
Git.

I found my solution from https://issues.guix.gnu.org/47573.

>    If you get an error like this one:
> 
>      configure.ac:46: error: possibly undefined macro: PKG_CHECK_MODULES


 doc/guix.texi | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/doc/guix.texi b/doc/guix.texi
index ef9e4216b4..72cac183a5 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -1177,6 +1177,23 @@ Running the Test Suite
 substitutes are available for their dependencies (@pxref{Substitutes}).
 Some of them require a lot of storage space to hold VM images.
 
+If you encounter an error like this one:
+
+@example
+Compiling Scheme modules...
+ice-9/eval.scm:142:16: In procedure compile-top-call:
+error: all-system-tests: unbound variable
+hint: Did you forget `(use-modules (gnu tests))'?
+@end example
+
+@noindent
+there may be inconsistency in the work tree from previous builds.  Try
+running:
+
+@example
+make clean && make
+@end example
+
 Again in case of test failures, please send @email{bug-guix@@gnu.org}
 all the details.
 

base-commit: ade6845da6cec99f3bca46faac9b2bad6877817e
-- 
2.41.0