bug#25882: gcc-wrapper doesn't handle response files

[Ludovic Courtès]

Federico Beffa <address@hidden> skribis:

> address@hidden (Ludovic Courtès) writes:
>
>> Federico Beffa <address@hidden> skribis:
>>
>>> gcc-wrapper doesn't handle compiler/linker flags passed through
>>> response files.
>>>
>>> One package which recently started using such files is GHC (I believe
>>> since 7.10.3).  For this reason we currently need to patch it.
>>> However, the problem is with our tool chain wrapper and not with GHC
>>> itself.
>>>
>>> See discussion at
>>> https://lists.gnu.org/archive/html/guix-devel/2017-01/msg01981.html
>>
>> Given that the GHC patch is so small, I have a slight preference for
>> keeping ld-wrapper unchanged and using the GHC patch.  To put it
>> differently, the GHC patch is smaller and less error-prone than the
>> changes that would need to be made in ld-wrapper.
>
> I don't think that it is a good idea because any upstream change around
> that code will break our package again and, going forward, we may find
> other pieces of software making use of this gcc feature.  The patch is
> small, but the effort to find it wasn't.
>
> I like to fix things where the problem is, not working around it.

On closer inspection, it’s an easy change to make.

Could you test the attached patch with GHC?

The way I would test it without rebuilding the world is by copying the
new ld-wrapper.in to ld-wrapper2.in (and thus keeping ld-wrapper.in
unchanged), and then adding it as an input to GHC (via
‘make-ld-wrapper’).  Commit 77db91addc57faa000db05563820f57a9ffdedfc
might serve as an example.

Thanks,
Ludo’.

diff --git a/gnu/packages/ld-wrapper.in b/gnu/packages/ld-wrapper.in
index ebfd8332c..ff086154a 100644
--- a/gnu/packages/ld-wrapper.in
+++ b/gnu/packages/ld-wrapper.in
@@ -15,7 +15,7 @@ main="(@ (gnu build-support ld-wrapper) ld-wrapper)"
 exec @GUILE@ -c "(load-compiled \"@address@hidden") (apply $main (cdr 
(command-line)))" "$@"
 !#
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012, 2013, 2014, 2015, 2016 Ludovic Courtès <address@hidden>
+;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès 
<address@hidden>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -35,6 +35,7 @@ exec @GUILE@ -c "(load-compiled \"@address@hidden") (apply 
$main (cdr (command-line))
 (define-module (gnu build-support ld-wrapper)
   #:use-module (srfi srfi-1)
   #:use-module (ice-9 match)
+  #:autoload   (ice-9 rdelim) (read-string)
   #:export (ld-wrapper))
 
 ;;; Commentary:
@@ -222,9 +223,28 @@ impure library ~s~%"
               '()
               library-files))
 
+(define (expand-arguments args)
+  ;; Expand ARGS such that "response file" arguments, such as "@args.txt", are
+  ;; expanded.  See 'expandargv' in libiberty.
+  (define (response-file-arguments file)
+    (when %debug?
+      (format (current-error-port)
+              "ld-wrapper: reading arguments from '~a'~%" file))
+    (string-tokenize (call-with-input-file file read-string)))
+
+  (fold-right (lambda (arg result)
+                (if (string-prefix? "@" arg)
+                    (let ((file (string-drop arg 1)))
+                      (append (response-file-arguments file)
+                              result))
+                    (cons arg result)))
+              '()
+              args))
+
 (define (ld-wrapper . args)
   ;; Invoke the real `ld' with ARGS, augmented with `-rpath' switches.
-  (let* ((path (library-search-path args))
+  (let* ((args (expand-arguments args))
+         (path (library-search-path args))
          (libs (library-files-linked args path))
          (args (append args (rpath-arguments libs))))
     (when %debug?