03/08: utils: 'current-source-directory' resolves relative file names at run time.

[Ludovic Courtès]

civodul pushed a commit to branch master
in repository guix.

commit cbbbb7be0fbaa11ff75bce92f2d82131ff8db104
Author: Ludovic Courtès <address@hidden>
Date:   Sun Jun 19 22:15:15 2016 +0200

    utils: 'current-source-directory' resolves relative file names at run time.
    
    * guix/utils.scm (absolute-dirname): New procedure.
    (current-source-directory): Emit code to use it instead of calling
    'search-path'.
---
 guix/utils.scm |   20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/guix/utils.scm b/guix/utils.scm
index a642bd3..0e20be3 100644
--- a/guix/utils.scm
+++ b/guix/utils.scm
@@ -702,6 +702,18 @@ output port, and PROC's result is returned."
 ;;; Source location.
 ;;;
 
+(define (absolute-dirname file)
+  "Return the absolute name of the directory containing FILE, or #f upon
+failure."
+  (match (search-path %load-path file)
+    (#f #f)
+    ((? string? file)
+     ;; If there are relative names in %LOAD-PATH, FILE can be relative and
+     ;; needs to be canonicalized.
+     (if (string-prefix? "/" file)
+         (dirname file)
+         (canonicalize-path (dirname file))))))
+
 (define-syntax current-source-directory
   (lambda (s)
     "Return the absolute name of the current directory, or #f if it could not
@@ -711,11 +723,13 @@ be determined."
        (match (assq 'filename (syntax-source s))
          (('filename . (? string? file-name))
           ;; If %FILE-PORT-NAME-CANONICALIZATION is 'relative, then FILE-NAME
-          ;; can be relative.  In that case, we try to find out the absolute
-          ;; file name by looking at %LOAD-PATH.
+          ;; can be relative.  In that case, we try to find out at run time
+          ;; the absolute file name by looking at %LOAD-PATH; doing this at
+          ;; run time rather than expansion time is necessary to allow files
+          ;; to be moved on the file system.
           (if (string-prefix? "/" file-name)
               (dirname file-name)
-              (and=> (search-path %load-path file-name) dirname)))
+              #`(absolute-dirname #,file-name)))
          (_
           #f))))))