bug#50299: [PATCH v4 09/25] gnu: swi-prolog: Set PROG_SWIPL when cross-compiling.

[Maxime Devos <maximedevos@telenet.be>]

* gnu/packages/prolog.scm
  (swi-prolog)[arguments]<#:configure-flags>: Set PROG_SWIPL and
  SWIPL_NATIVE_FRIEND when cross-compiling and make this a G-expression.
  (swi-prolog)[native-inputs]: Add 'this-package' when cross-compiling.
---
 gnu/packages/prolog.scm | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/gnu/packages/prolog.scm b/gnu/packages/prolog.scm
index 3eaec533d7..00f09b49cc 100644
--- a/gnu/packages/prolog.scm
+++ b/gnu/packages/prolog.scm
@@ -22,11 +22,13 @@
 
 (define-module (gnu packages prolog)
   #:use-module (guix download)
+  #:use-module (guix gexp)
   #:use-module (guix git-download)
   #:use-module ((guix licenses) #:prefix license:)
   #:use-module (guix packages)
   #:use-module (guix build-system cmake)
   #:use-module (guix build-system gnu)
+  #:use-module (guix utils)
   #:use-module (gnu packages backup)
   #:use-module (gnu packages bash)
   #:use-module (gnu packages compression)
@@ -100,16 +102,23 @@ manner.  It also features an interactive interpreter.")
     (arguments
      `(#:parallel-build? #t
        #:configure-flags
-       (list ,@(if (%current-target-system)
-                   ;; Set this manually, otherwise CMake would need to
-                   ;; run a cross-compiled binary, which it can't do.
-                   ;; These values were found on a Linux system.
-                   '("-DBSD_SIGNALS=1" "-DQSORT_R_GNU=1"
+       ,#~(list
+           #$@(if (%current-target-system)
+                  ;; Set this manually, otherwise CMake would need to
+                  ;; run a cross-compiled binary, which it can't do.
+                  ;; These values were found on a Linux system.
+                  #~("-DBSD_SIGNALS=1" "-DQSORT_R_GNU=1"
                      ;; If absent, the non-existent 'cc' is used.
                      "-DCMAKE_HOST_CC=gcc"
-                   '())
-             "-DINSTALL_DOCUMENTATION=ON"
-             "-DSWIPL_INSTALL_IN_LIB=OFF") ; FIXME: Breaks RUNPATH validation.
+                     ;; swi-prolog needs a native copy of itself for
+                     ;; cross-compilation.
+                     "-DSWIPL_NATIVE_FRIEND=/nowhere"
+                     (string-append "-DPROG_SWIPL="
+                                    #+(this-package-native-input "swi-prolog")
+                                    "/bin/swipl"))
+                  #~())
+           "-DINSTALL_DOCUMENTATION=ON"
+           "-DSWIPL_INSTALL_IN_LIB=OFF") ; FIXME: Breaks RUNPATH validation.
        #:phases
        (modify-phases %standard-phases
          ;; XXX: Delete the test phase that attempts to write to the
@@ -125,7 +134,15 @@ manner.  It also features an interactive interpreter.")
                          '("save")))
              #t)))))
     (native-inputs
-     `(("texinfo" ,texinfo)
+     `(,@(if (%current-target-system)
+             (begin
+               (unless (equal? (target-64bit?)
+                               (target-64bit? (%current-system)))
+                 (error "swi-prolog requires --system and --target to have \
+the same word size"))
+               `(("swi-prolog" ,this-package)))
+             '())
+       ("texinfo" ,texinfo)
        ("perl" ,perl)
        ("pkg-config" ,pkg-config)))
     (inputs
-- 
2.30.2