[bug#72751] [PATCH 1/2] guix: build-system: cmake: Rework cross compilation.

[Dariqq]

Move the extra configure flags for cross building out from the build side code 
and instead
prepend them to the configure-flags.

Use new procedure cmake-system-name-for-target to add support for hurd and
bare-metal targets.

* guix/build/cmake-build-system.scm (configure): Move cross build flags from
here ...
* guix/build-system/cmake.scm (cmake-cross-build): ... to here.
(cmake-system-name-for-target): New procedure.

Change-Id: Ic68acc246e543491ed147e53d47cec5de46b82cb
---
 guix/build-system/cmake.scm       | 19 ++++++++++++++++++-
 guix/build/cmake-build-system.scm | 11 -----------
 2 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/guix/build-system/cmake.scm b/guix/build-system/cmake.scm
index aa187c9844..fd32548342 100644
--- a/guix/build-system/cmake.scm
+++ b/guix/build-system/cmake.scm
@@ -39,6 +39,15 @@ (define-module (guix build-system cmake)
 ;;
 ;; Code:
 
+(define* (cmake-system-name-for-target
+          #:optional (target (or (%current-target-system)
+                                 (%current-system))))
+  (cond ((target-hurd? target)  "GNU")
+        ((target-linux? target) "Linux")
+        ((target-mingw? target) "Windows")
+        ;; For avr, or1k-elf, xtensa-ath9k-elf
+        (else "Generic")))
+
 (define %cmake-build-system-modules
   ;; Build-side modules imported by default.
   `((guix build cmake-build-system)
@@ -228,7 +237,15 @@ (define* (cmake-cross-build name
                                                  
search-path-specification->sexp
                                                  native-search-paths)
                        #:phases #$phases
-                       #:configure-flags #$configure-flags
+                       #:configure-flags `(#$(string-append 
"-DCMAKE_C_COMPILER="
+                                                            (cc-for-target 
target))
+                                           #$(string-append 
"-DCMAKE_CXX_COMPILER="
+                                                            (cxx-for-target 
target))
+                                           #$(string-append 
"-DCMAKE_SYSTEM_NAME="
+                                                            
(cmake-system-name-for-target target))
+                                           ,@#$(if (pair? configure-flags)
+                                                   (sexp->gexp configure-flags)
+                                                   configure-flags))
                        #:make-flags #$make-flags
                        #:out-of-source? #$out-of-source?
                        #:build-type #$build-type
diff --git a/guix/build/cmake-build-system.scm 
b/guix/build/cmake-build-system.scm
index d1ff5071be..61033061c6 100644
--- a/guix/build/cmake-build-system.scm
+++ b/guix/build/cmake-build-system.scm
@@ -62,17 +62,6 @@ (define* (configure #:key outputs (configure-flags '()) 
(out-of-source? #t)
                   ,(string-append "-DCMAKE_INSTALL_RPATH=" out "/lib")
                   ;; enable verbose output from builds
                   "-DCMAKE_VERBOSE_MAKEFILE=ON"
-
-                  ;;  Cross-build
-                  ,@(if target
-                        (list (string-append "-DCMAKE_C_COMPILER="
-                                             target "-gcc")
-                              (string-append "-DCMAKE_CXX_COMPILER="
-                                             target "-g++")
-                              (if (string-contains target "mingw")
-                                  "-DCMAKE_SYSTEM_NAME=Windows"
-                                  "-DCMAKE_SYSTEM_NAME=Linux"))
-                        '())
                   ,@configure-flags)))
       (format #t "running 'cmake' with arguments ~s~%" args)
       (apply invoke "cmake" args))))
-- 
2.45.2