gexp: computed-file: Prevent mistakenly overriding default option values.

In order to do so, default to an empty options list, and expose options whose
default values are sensitive directly as keyword arguments.

* guix/gexp.scm (computed-file): Extract the LOCAL-BUILD? parameter from the
OPTIONS parameter to make it a stand-alone keyword argument.  Introduce an
OPTIONS* binding which is obtained by combining the LOCAL-BUILD? keyword and
its value with OPTIONS.
* doc/guix.texi (G-Expressions): Adjust doc.

Suggested-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 56b1cd8976..b1b0ab37d4 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -8327,10 +8327,12 @@ This is the declarative counterpart of @code{text-file}.
 @end deffn
 
 @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
-          [#:options '(#:local-build? #t)]
+          [#:local-build? #t]
+          [#:options '()]
 Return an object representing the store item @var{name}, a file or
-directory computed by @var{gexp}.  @var{options}
-is a list of additional arguments to pass to @code{gexp->derivation}.
+directory computed by @var{gexp}.  When @var{local-build?} is true (the
+default), the derivation is built locally.  @var{options} is a list of
+additional arguments to pass to @code{gexp->derivation}.
 
 This is the declarative counterpart of @code{gexp->derivation}.
 @end deffn