build-system: Introduce "bags" as an intermediate representation.

* guix/build-system.scm (<build-system>)[build, cross-build]: Remove.
  [lower]: New field.
  (<bag>): New record type.
  (make-bag): New procedure.
* guix/packages.scm (bag-transitive-inputs, bag-transitive-build-inputs,
  bag-transitive-host-inputs, bag-transitive-target-inputs,
  package->bag): New procedures.
  (package-derivation): Use it; use the bag, apply its build procedure,
  etc.
  (package-cross-derivation): Likewise.
* gnu/packages/bootstrap.scm (raw-build, make-raw-bag): New procedure.
  (%bootstrap-guile): Use them.
* guix/build-system/trivial.scm (lower): New procedure.
  (trivial-build, trivial-cross-build): Remove 'source' parameter.  Pass
  INPUTS as is.
  (trivial-build-system): Adjust accordingly.
* guix/build-system/gnu.scm (%store, inputs-search-paths,
  standard-search-paths, expand-inputs, standard-inputs): Remove.
  (gnu-lower): New procedure.
  (gnu-build): Remove 'source' and #:implicit-inputs? parameters.
  Remove 'implicit-inputs' and 'implicit-search-paths' variables.  Get
  the source from INPUT-DRVS.
  (gnu-cross-build): Likewise.
  (standard-cross-packages): Remove call to 'standard-packages'.
  (standard-cross-inputs, standard-cross-search-paths): Remove.
  (gnu-build-system): Remove 'build' and 'cross-build'; add 'lower'.
* guix/build-system/cmake.scm (lower): New procedure.
  (cmake-build): Remove 'source' and #:cmake parameters.  Use INPUTS and
  SEARCH-PATHS as is.  Get the source from INPUTS.
* guix/build-system/perl.scm: Likewise.
* guix/build-system/python.scm: Likewise.
* guix/build-system/ruby.scm: Likewise.
* gnu/packages/cross-base.scm (cross-gcc): Change "cross-linux-headers"
  to "linux-headers".
  (cross-libc)[xlinux-headers]: Pass #:implicit-cross-inputs? #f.
  Likewise.  In 'propagated-inputs', change "cross-linux-headers" to
  "linux-headers".
* guix/git-download.scm (git-fetch): Use 'standard-packages' instead of
  'standard-inputs'.
* tests/builders.scm ("gnu-build-system"): Remove use of
  'build-system-builder'.
  ("gnu-build"): Remove 'source' and #:implicit-inputs? arguments to
  'gnu-build'.
* tests/packages.scm ("search paths"): Adjust to new build system API.
  ("package-cross-derivation, no cross builder"): Likewise.
* doc/guix.texi (Build Systems): Add paragraph on bags.

2 files changed, 60 insertions, 38 deletions

diff --git a/gnu/packages/bootstrap.scm b/gnu/packages/bootstrap.scm
index 71ccb19597..efa8cd89eb 100644
--- a/gnu/packages/bootstrap.scm
+++ b/gnu/packages/bootstrap.scm
@@ -164,6 +164,46 @@ check whether everything is alright."
 ;;; Bootstrap packages.
 ;;;
 
+(define* (raw-build store name inputs
+                    #:key outputs system search-paths
+                    #:allow-other-keys)
+  (define (->store file)
+    (add-to-store store file #t "sha256"
+                  (or (search-bootstrap-binary file
+                                               system)
+                      (error "bootstrap binary not found"
+                             file system))))
+
+  (let* ((tar   (->store "tar"))
+         (xz    (->store "xz"))
+         (mkdir (->store "mkdir"))
+         (bash  (->store "bash"))
+         (guile (->store "guile-2.0.9.tar.xz"))
+         (builder
+          (add-text-to-store store
+                             "build-bootstrap-guile.sh"
+                             (format #f "
+echo \"unpacking bootstrap Guile to '$out'...\"
+~a $out
+cd $out
+~a -dc < ~a | ~a xv
+
+# Sanity check.
+$out/bin/guile --version~%"
+                                     mkdir xz guile tar)
+                             (list mkdir xz guile tar))))
+    (derivation store name
+                bash `(,builder)
+                #:system system
+                #:inputs `((,bash) (,builder)))))
+
+(define* (make-raw-bag name
+                       #:key source inputs native-inputs outputs target)
+  (bag
+    (name name)
+    (build-inputs inputs)
+    (build raw-build)))
+
 (define %bootstrap-guile
   ;; The Guile used to run the build scripts of the initial derivations.
   ;; It is just unpacked from a tarball containing a pre-built binary.
@@ -172,39 +212,9 @@ check whether everything is alright."
   ;; XXX: Would need libc's `libnss_files2.so' for proper `getaddrinfo'
   ;; support (for /etc/services).
   (let ((raw (build-system
-              (name "raw")
-              (description "Raw build system with direct store access")
-              (build (lambda* (store name source inputs
-                                     #:key outputs system search-paths)
-                       (define (->store file)
-                         (add-to-store store file #t "sha256"
-                                       (or (search-bootstrap-binary file
-                                                                    system)
-                                           (error "bootstrap binary not found"
-                                                  file system))))
-
-                       (let* ((tar   (->store "tar"))
-                              (xz    (->store "xz"))
-                              (mkdir (->store "mkdir"))
-                              (bash  (->store "bash"))
-                              (guile (->store "guile-2.0.9.tar.xz"))
-                              (builder
-                               (add-text-to-store store
-                                                  "build-bootstrap-guile.sh"
-                                                  (format #f "
-echo \"unpacking bootstrap Guile to '$out'...\"
-~a $out
-cd $out
-~a -dc < ~a | ~a xv
-
-# Sanity check.
-$out/bin/guile --version~%"
-                                                          mkdir xz guile tar)
-                                                  (list mkdir xz guile tar))))
-                         (derivation store name
-                                     bash `(,builder)
-                                     #:system system
-                                     #:inputs `((,bash) (,builder)))))))))
+               (name 'raw)
+               (description "Raw build system with direct store access")
+               (lower make-raw-bag))))
    (package
      (name "guile-bootstrap")
      (version "2.0")
diff --git a/gnu/packages/cross-base.scm b/gnu/packages/cross-base.scm
index 90fc606d94..46909cb597 100644
--- a/gnu/packages/cross-base.scm
+++ b/gnu/packages/cross-base.scm
@@ -154,7 +154,7 @@ GCC that does not target a libc; otherwise, target that libc."
                      ;; them from CPATH.
                      (let ((libc  (assoc-ref inputs "libc"))
                            (linux (assoc-ref inputs
-                                             "libc/cross-linux-headers")))
+                                             "libc/linux-headers")))
                        (define (cross? x)
                          ;; Return #t if X is a cross-libc or cross Linux.
                          (or (string-prefix? libc x)
@@ -224,7 +224,9 @@ XBINUTILS and the cross tool chain."
       (name (string-append (package-name linux-libre-headers)
                            "-cross-" target))
       (arguments
-       (substitute-keyword-arguments (package-arguments linux-libre-headers)
+       (substitute-keyword-arguments
+           `(#:implicit-cross-inputs? #f
+             ,@(package-arguments linux-libre-headers))
          ((#:phases phases)
           `(alist-replace
             'build
@@ -243,7 +245,14 @@ XBINUTILS and the cross tool chain."
     (name (string-append "glibc-cross-" target))
     (arguments
      (substitute-keyword-arguments
-         `(#:strip-binaries? #f                ; disable stripping (see above)
+         `(;; Disable stripping (see above.)
+           #:strip-binaries? #f
+
+           ;; This package is used as a target input, but it should not have
+           ;; the usual cross-compilation inputs since that would include
+           ;; itself.
+           #:implicit-cross-inputs? #f
+
            ,@(package-arguments glibc))
        ((#:configure-flags flags)
         `(cons ,(string-append "--host=" target)
@@ -252,13 +261,16 @@ XBINUTILS and the cross tool chain."
         `(alist-cons-before
           'configure 'set-cross-linux-headers-path
           (lambda* (#:key inputs #:allow-other-keys)
-            (let ((linux (assoc-ref inputs "cross-linux-headers")))
+            (let ((linux (assoc-ref inputs "linux-headers")))
               (setenv "CROSS_CPATH"
                       (string-append linux "/include"))
               #t))
           ,phases))))
 
-    (propagated-inputs `(("cross-linux-headers" ,xlinux-headers)))
+    ;; Shadow the native "linux-headers" because glibc's recipe expect the
+    ;; "linux-headers" input to point to the right thing.
+    (propagated-inputs `(("linux-headers" ,xlinux-headers)))
+
     (native-inputs `(("cross-gcc" ,xgcc)
                      ("cross-binutils" ,xbinutils)
                      ,@(package-native-inputs glibc)))))