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01/02: gexp: Slightly improve error reporting for 'local-file'.
From: |
Ludovic Courtès |
Subject: |
01/02: gexp: Slightly improve error reporting for 'local-file'. |
Date: |
Thu, 20 Jul 2017 12:08:10 -0400 (EDT) |
civodul pushed a commit to branch master
in repository guix.
commit 302d46e63f406f0f8acb024557498deaef2d4255
Author: Ludovic Courtès <address@hidden>
Date: Thu Jul 20 15:48:09 2017 +0200
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.
---
guix/gexp.scm | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/guix/gexp.scm b/guix/gexp.scm
index 2094c49..2622c5c 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