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authorLudovic Courtès <ludo@gnu.org>2017-07-20 15:48:09 +0200
committerLudovic Courtès <ludo@gnu.org>2017-07-20 18:08:00 +0200
commit302d46e63f406f0f8acb024557498deaef2d4255 (patch)
treedf2a11a0f30678327c2463c5d9195a54d92bff3f /guix/gexp.scm
parentfb5dfa86b1b2a6601a773869f021a959757076fd (diff)
gexp: Slightly improve error reporting for 'local-file'.
Reported by Ricardo Wurmus. * guix/gexp.scm (local-file): Define using 'syntax-case' instead of 'syntax-rules'. Explicitly handle the zero-argument case and the use-as-an-identifier case.
Diffstat (limited to 'guix/gexp.scm')
-rw-r--r--guix/gexp.scm26
1 files changed, 20 insertions, 6 deletions
diff --git a/guix/gexp.scm b/guix/gexp.scm
index 2094c495d6..2622c5cb62 100644
--- a/guix/gexp.scm
+++ b/guix/gexp.scm
@@ -269,8 +269,9 @@ vicinity of DIRECTORY."
(string-append directory "/" file))
(else file))))
-(define-syntax-rule (local-file file rest ...)
- "Return an object representing local file FILE to add to the store; this
+(define-syntax local-file
+ (lambda (s)
+ "Return an object representing local file FILE to add to the store; this
object can be used in a gexp. If FILE is a relative file name, it is looked
up relative to the source file where this form appears. FILE will be added to
the store under NAME--by default the base name of FILE.
@@ -283,10 +284,23 @@ When RECURSIVE? is true, call (SELECT? FILE STAT) for each directory entry,
where FILE is the entry's absolute file name and STAT is the result of
'lstat'; exclude entries for which SELECT? does not return true.
-This is the declarative counterpart of the 'interned-file' monadic procedure."
- (%local-file file
- (delay (absolute-file-name file (current-source-directory)))
- rest ...))
+This is the declarative counterpart of the 'interned-file' monadic procedure.
+It is implemented as a macro to capture the current source directory where it
+appears."
+ (syntax-case s ()
+ ((_ file rest ...)
+ #'(%local-file file
+ (delay (absolute-file-name file (current-source-directory)))
+ rest ...))
+ ((_)
+ #'(syntax-error "missing file name"))
+ (id
+ (identifier? #'id)
+ ;; XXX: We could return #'(lambda (file . rest) ...). However,
+ ;; (syntax-source #'id) is #f so (current-source-directory) would not
+ ;; work. Thus, simply forbid this form.
+ #'(syntax-error
+ "'local-file' is a macro and cannot be used like this")))))
(define (local-file-absolute-file-name file)
"Return the absolute file name for FILE, a <local-file> instance. A