packages: Recommend against the use of 'package-file'.

* guix/packages.scm (package-file): Recommend against its use in the
docstring.
* doc/guix.texi (The Store Monad): Likewise.

2 files changed, 9 insertions, 1 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index d2cd11576f..a79bbfc4f7 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -7483,6 +7483,10 @@ value in the absolute file name of @var{file} within the @var{output}
 directory of @var{package}.  When @var{file} is omitted, return the name
 of the @var{output} directory of @var{package}.  When @var{target} is
 true, use it as a cross-compilation target triplet.
+
+Note that this procedure does @emph{not} build @var{package}.  Thus, the
+result might or might not designate an existing file.  We recommend not
+using this procedure unless you know what you are doing.
 @end deffn
 
 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
diff --git a/guix/packages.scm b/guix/packages.scm
index 6c6a06e0ce..2fa4fd05d7 100644
--- a/guix/packages.scm
+++ b/guix/packages.scm
@@ -1340,7 +1340,11 @@ code of derivations to GUILE, a package object."
   "Return as a monadic value the absolute file name of FILE within the
 OUTPUT directory of PACKAGE.  When FILE is omitted, return the name of the
 OUTPUT directory of PACKAGE.  When TARGET is true, use it as a
-cross-compilation target triplet."
+cross-compilation target triplet.
+
+Note that this procedure does _not_ build PACKAGE.  Thus, the result might or
+might not designate an existing file.  We recommend not using this procedure
+unless you know what you are doing."
   (lambda (store)
     (define compute-derivation
       (if target