gnu: Add gcc-arm-none-eabi-7-2018-q2-update.

* gnu/packages/embedded.scm (gcc-arm-none-eabi-7-2018-q2-update): New
variable.
* gnu/packages/patches/gcc-7-cross-environment-variables.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

gnu/packages/embedded.scm

@@ -207,6 +207,84 @@ usable on embedded products.")
            "--disable-nls"))))
     (synopsis "Newlib variant for small systems with limited memory")))
 
+
+;;; The following definitions are for the "7-2018-q2-update" variant of the
+;;; ARM cross toolchain as offered on https://developer.arm.com
+(define-public gcc-arm-none-eabi-7-2018-q2-update
+  (let ((xgcc (cross-gcc "arm-none-eabi"
+                         #:xgcc gcc-7
+                         #:xbinutils (cross-binutils "arm-none-eabi")))
+        (revision "1")
+        (svn-revision 261907))
+    (package (inherit xgcc)
+      (version (string-append "7-2018-q2-update-"
+                              revision "." (number->string svn-revision)))
+      (source
+       (origin
+         (method svn-fetch)
+         (uri (svn-reference
+               (url "svn://gcc.gnu.org/svn/gcc/branches/ARM/embedded-7-branch/")
+               (revision svn-revision)))
+         (file-name (string-append "gcc-arm-embedded-" version "-checkout"))
+         (sha256
+          (base32
+           "192ggs63bixf3irpijgfkjks73yx1r3a4i6grk1y0i0iny76pmx5"))
+         (patches
+          (append
+           (origin-patches (package-source gcc-7))
+           (search-patches "gcc-7-cross-environment-variables.patch")))))
+      (native-inputs
+       `(("gcc" ,gcc-5)
+         ("flex" ,flex)
+         ("isl" ,isl-0.18)
+         ,@(alist-delete "isl" (package-native-inputs xgcc))))
+      (arguments
+       (substitute-keyword-arguments (package-arguments xgcc)
+         ((#:phases phases)
+          `(modify-phases ,phases
+             (add-after 'unpack 'expand-version-string
+               (lambda _
+                 (make-file-writable "gcc/DEV-PHASE")
+                 (with-output-to-file "gcc/DEV-PHASE"
+                   (lambda ()
+                     (display "7-2018-q2-update")))
+                 #t))
+             (add-after 'unpack 'fix-genmultilib
+               (lambda _
+                 (substitute* "gcc/genmultilib"
+                   (("#!/bin/sh") (string-append "#!" (which "sh"))))
+                 #t))))
+         ((#:configure-flags flags)
+          ;; The configure flags are largely identical to the flags used by the
+          ;; "GCC ARM embedded" project.
+          `(append (list "--enable-multilib"
+                         "--with-newlib"
+                         "--with-multilib-list=rmprofile"
+                         "--with-host-libstdcxx=-static-libgcc -Wl,-Bstatic,-lstdc++,-Bdynamic -lm"
+                         "--enable-plugins"
+                         "--disable-decimal-float"
+                         "--disable-libffi"
+                         "--disable-libgomp"
+                         "--disable-libmudflap"
+                         "--disable-libquadmath"
+                         "--disable-libssp"
+                         "--disable-libstdcxx-pch"
+                         "--disable-nls"
+                         "--disable-shared"
+                         "--disable-threads"
+                         "--disable-tls")
+                   (delete "--disable-multilib" ,flags)))))
+      (native-search-paths
+       (list (search-path-specification
+              (variable "CROSS_C_INCLUDE_PATH")
+              (files '("arm-none-eabi/include")))
+             (search-path-specification
+              (variable "CROSS_CPLUS_INCLUDE_PATH")
+              (files '("arm-none-eabi/include")))
+             (search-path-specification
+              (variable "CROSS_LIBRARY_PATH")
+              (files '("arm-none-eabi/lib"))))))))
+
 (define (make-libstdc++-arm-none-eabi xgcc newlib)
   (let ((libstdc++ (make-libstdc++ xgcc)))
     (package (inherit libstdc++)