01/07: channels: 'build-from-source' restores '%guile-for-build'.

[guix-commits]

civodul pushed a commit to branch master
in repository guix.

commit 9db8836916d0e79f86ac63fbd9b77096d83abfa1
Author: Ludovic Courtès <address@hidden>
AuthorDate: Fri May 15 11:53:13 2020 +0200

    channels: 'build-from-source' restores '%guile-for-build'.
    
    Not restoring it would cause problems when running:
    
      guix time-machine --commit=6298c3ffd9654d3231a6f25390b056483e8f407c
    
    or similar because the target Guix would be built with 2.2, and then
    we'd erroneously go on and attempt build the profile with 2.2.  This
    would fail because profile dependencies such as "guile-gdbm-ffi" now
    target 3.0.
    
    * guix/channels.scm (call-with-guile): New procedure.
    (with-guile): New macro.
    (build-from-source): Use it instead of calling 'set-guile-for-build'
    just once.  This ensures that '%guile-for-build' is restored
    afterwards.
---
 guix/channels.scm | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/guix/channels.scm b/guix/channels.scm
index aca8302..f0174de 100644
--- a/guix/channels.scm
+++ b/guix/channels.scm
@@ -347,6 +347,21 @@ to '%package-module-path'."
       (((predicate . guile) rest ...)
        (if (predicate source) (guile) (loop rest))))))
 
+(define (call-with-guile guile thunk)
+  (lambda (store)
+    (values (parameterize ((%guile-for-build
+                            (if guile
+                                (package-derivation store guile)
+                                (%guile-for-build))))
+              (run-with-store store (thunk)))
+            store)))
+
+(define-syntax-rule (with-guile guile exp ...)
+  "Set GUILE as the '%guile-for-build' parameter for the dynamic extent of
+EXP, a series of monadic expressions."
+  (call-with-guile guile (lambda ()
+                           (mbegin %store-monad exp ...))))
+
 (define (with-trivial-build-handler mvalue)
   "Run MVALUE, a monadic value, with a \"trivial\" build handler installed
 that unconditionally resumes the continuation."
@@ -385,10 +400,7 @@ package modules under SOURCE using CORE, an instance of 
Guix."
         ;; Note: BUILD can return #f if it does not support %PULL-VERSION.  In
         ;; the future we'll fall back to a previous version of the protocol
         ;; when that happens.
-        (mbegin %store-monad
-          (mwhen guile
-            (set-guile-for-build guile))
-
+        (with-guile guile
           ;; BUILD is usually quite costly.  Install a "trivial" build handler
           ;; so we don't bounce an outer build-accumulator handler that could
           ;; cause us to redo half of the BUILD computation several times just
@@ -750,3 +762,7 @@ NEW.  When OLD is omitted or is #f, return all the news 
entries of CHANNEL."
       (if (= GIT_ENOTFOUND (git-error-code error))
           '()
           (apply throw key error rest)))))
+
+;;; Local Variables:
+;;; eval: (put 'with-guile 'scheme-indent-function 1)
+;;; End: